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© 2005, 1970 Copeland Corporation.Printed in the U.S.A.

Part 5 - Installation and Service

Refrigeration Manual


This is the fifth and last of a series of publications comprising the Copeland RefrigerationManual.

Part 1 — Fundamentals of RefrigerationPart 2 — Refrigeration System ComponentsPart 3 — The Refrigeration LoadPart 4 — System DesignPart 5 — Installation and Service

The installation and service information is intended as a guide to good installation prac-tice, and as an aid in analyzing system malfunctions. The section on service fundamen-tals is designed to serve as an introduction to various service procedures for beginningservice men, students, salesmen, and others, needing a basic understanding of servicetechniques.


PART 5INSTALLATION AND SERVICE

Section 24. INSTALLATION

Recommended Installation Procedures 24- 1

Fundamentals of Evacuationand Dehydration ....................................24- 6

Brazing Connections on CopelaweldMotor Compressors .............................. 24-11

Installation of Suction and DischargeLine Vibration Absorbers ...................... 24-13

Typical Installation Specifications ......... 24-14

Section 25. SERVICING COPELANDCOMPRESSORS

Copeland Nameplate Identification .......25- 1

Identification of Port Locations inHeads of CopelameticMotor-Compressors .............................. 25- 5

Identification of Motor Terminals onSingle Phase Compressors .................. 25- 5

Proper Valve Plate and Head Gasketsfor 3, 4, and 6 CylinderCompressors .... 25- 6

Copeland Oil Pumps ............................. 25-10

Typical Copelametic CompressorConstruction .......................................... 25-15

Maintenance Accessibility onCopelametic Compressors ................... 25-20

Field Troubleshooting ...........................25-23

Section 26. FUNDAMENTALS OF SERVICEOPERATION

Contaminants ........................................ 26- 1

Handling of Refrigerant Containers ......26- 2

Safe Handling of Compressed GasesWhen Testing or CleaningRefrigeration Systems ..........................26- 3

Handling Copper Tubing ....................... 26- 6

Brazing Refrigerant Lines ..................... 26- 6

Service Valves ...................................... 26- 8

The Gauge Manifold ............................. 26- 9

Purging Non-Condensables.................. 26-10

System Pumpdown ............................... 26-11

Refrigerant Leaks ................................. 26-11

Evacuation ............................................ 26-13

Charging Refrigerant Into a System .....26-14

Removing Refrigerant From a System .26-18

Handling Refrigeration Oil ..................... 26-18

Determining The Oil Level .................... 26-19

Adding Oil To a Compressor ................26-19

Removing Oil From a Compressor .......26-20

Handling Filter-Driers ............................ 26-22

Compressor Burnouts—What to do .....26-22

Compressor Failures That CouldHave Been Prevented ...........................26-25

Preventive Maintenance ....................... 26-30

Section 27. USEFUL ENGINEERING DATA


INDEX OF TABLES

Table 49 Boiling Point of Water at Varying Pressures ............................................................... 24-8

Table 50 Comparison of Gauge and Absolute Pressures at Varying Altitudes .........................24-8

Table 51 Melting Points of Typical Commercial Brazing Compounds ....................................... 24-12

Table 52 Service Diagnosis Chart .............................................................................................. 25-29

Table 53 Temperature Scales .................................................................................................... 27-1

Table 54 International Rating Conditions ................................................................................... 27-1

Table 55 Thermal Units .............................................................................................................. 27-2

Table 56 Fahrenheit—Centigrade Temperature Conversion Chart ........................................... 27-3

Table 57 Properties of Saturated Steam .................................................................................... 27-4

Table 58 Decimal Equivalents, Areas, and Circumferences of Circles ......................................27-5

Table 59 Conversion Table — Inches into Millimeters ............................................................... 27-6

Table 60 Conversion Table — Decimals of an Inch into Millimeters .......................................... 27-7

Table 61 Conversion Table — Millimeters into Inches ............................................................... 27-7

Table 62 Conversion Table — Hundredths of Millimeter into Inches ......................................... 27-9

Table 63 Metric Prefixes ............................................................................................................. 27-9

Table 64 Length .......................................................................................................................... 27-10

Table 65 Area .............................................................................................................................27-10

Table 66 Weight, Avoirdupois..................................................................................................... 27-10

Table 67 Volume, Dry ................................................................................................................. 27-11

Table 68 Volume, Liquid ............................................................................................................. 27-11

Table 69 Density ......................................................................................................................... 27-11

Table 70 Pressure ......................................................................................................................27-11

Table 71 Velocity ........................................................................................................................ 27-12

Table 72 Heat, Energy, Work .....................................................................................................27-12

Table 73 Solid and Liquid Expendable Refrigerants ..................................................................27-12


SECTION 24INSTALLATION

RECOMMENDED INSTALLATIONPROCEDURES

It is quite probable that a majority of operatingfailures on field installed systems can be traced tocareless or inadequate installation procedures.The following instructions have been prepared tohelp the installation and/or service engineer sys-tematically cover the many points which must beconsidered to provide each installation with troublefree performance.

These instructions are general in nature, and havebeen primarily for field installed and connectedsystems normally utilizing compressors 2 horse-power in size or larger. However, the procedurescan be applied to almost any type of field installedsystem, utilizing only those procedures which ap-ply to the specific installation.

Design and Application

A location for the compressor should be selectedwhich provides good ventilation, even when re-mote condensers are to be used, since the motor-compressor and discharge lines give off heat. Aircooled compressors must be provided with forcedconvection air cooling.

Air cooled condensers must be located to insureadequate air for condensing purposes. Care mustbe taken to avoid recirculation of air from onecondenser to another.

Water cooled units must be provided with anadequate supply of water to maintain desiredcondensing temperatures. In order to avoid con-centration of impurities, fungus, and scaling incooling towers and evaporative condensers, acontinuous waste bleed to a drain of approximately2 gallons per hour per horsepower must be pro-vided so that a continuous addition of fresh make-up water will be required.

Units and compressors must be level to insureproper lubrication.

Refrigerant suction lines must be sized to maintainadequate velocities for proper oil return.

Handling and Receiving of Equipment

Responsibility should be assigned to a depend-able individual at the job site to receive material.Each shipment should be carefully checked againstthe bill of lading. The shipping receipt should notbe signed until all items listed on the bill of ladinghave been accounted for.

Check carefully for concealed damage. Any short-age or damages should be reported to the deliver-ing carrier. Damaged material becomes the deliv-ering carrier’s responsibility, and should not bereturned to the manufacturer unless prior approvalis given to do so.

When uncrating, care should be taken to preventdamage. Heavy equipment should be left on itsshipping base until it has been moved to the finallocation.

The packing list included with each shipment shouldbe carefully checked to determine if all parts andequipment have been received. Any accessoriessuch as starters, contactors or controls should befastened to the basic unit to avoid loss and preventpossible interchanging with other units.

Installation, Electrical

The supply power, voltage, frequency, and phasemust coincide with the compressor nameplate. Allwiring should be carefully checked against themanufacturer’s diagrams. Field wiring must beconnected in accordance with the National ElectricCode, or other local codes that may apply.

Check to insure proper:

(a) Wire Sizes to handle the connected load.

(b) Fuses recommended for compressors. (SeeCopeland Electrical Handbook)

(c) Magnetic starters, contactors, and motor pro-tection devices approved by Copeland.

(d) Operation of oil pressure safety control.

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(e) Direction of rotation and speed of fans and/orwater pumps.

(f) Wiring with no grounded lines or controls.

Installation, Refrigerant Piping

Take extreme care to keep refrigeration tubingclean and dry prior to installation. The followingprocedures should be followed:

(a) Do not leave dehydrated compressors filter-driers open to the atmosphere any longer thanis absolutely necessary. (One or two minutesmaximum suggested.)

(b) Use only refrigeration grade copper tubing,properly sealed against contamination. Watertubing often contains wax and other trouble-some contaminants.

(c) Permanent suction line filters and liquid linefilter-driers are recommended in all field in-stalled systems.

(d) Suction lines should slope ½ inch per 10 feettowards the compressor.

(e) Suitable P-type oil traps should be located atthe base of each suction riser to enhance oilreturn to the compressor.

(f) When brazing refrigerant lines, an inert gasshould be passed through the line at lowpressure to prevent scaling and oxidation in-side the tubing. Dry nitrogen is preferred.

(g) Use only a suitable silver solder alloy or 95/5solder on suction and liquid lines, and a hightemperature silver solder alloy only on dis-charge lines.

(h) In order to avoid damage to the internal jointsin vibration eliminators, line connections tovibration eliminators should be made with asilver solder alloy such as Easy-Flo having amelting temperature of 900°F. to 1200°F.

(i) Limit the soldering paste or flux to the minimumrequired to prevent contamination of the s o l -der joint internally. Flux only the male portion of

the connection, never the female. After braz-ing, remove surplus flux with a damp cloth.

(j) If vibration absorbers are to be installed insuction or discharge lines they must be appliedaccording to the manufacturer’s recommen-dations. With Copelametic motor-compressors,the preferred position is parallel to the crank-shaft, as close to the compressor as possible.Vibration eliminators may be installed in avertical position if joints are sealed againsttrapping of condensation which might damagethe vibration absorber bellows due to freezing.Filling of the joints with soft solder as a meansof sealing is recommended. Installation of thevibration absorber in a horizontal plane at rightangles to the crankshaft is not acceptablesince the resulting stress from compressormovement may cause failure of the bellows orof the refrigerant line.

(k) Two evacuation valves are necessary. Oneshould be in the suction line and one in theliquid line at or near the receiver.

(l) After all lines are connected, the entire systemmust be leak tested. The complete systemshould be pressurized to not more than 175psig with refrigerant and dry nitrogen (or dryCO2). The use of an electronic type leak detec-tor is highly recommended because of itsgreater sensitivity to small leaks. As a furthercheck it is recommended that prior to charging,the system be evacuated to a pressure of 1PSIA or less, and sealed for 12 hours. Anyleakage of air into the system will cause thevacuum reading to decrease. If an air leak isindicated, the system should again be leaktested, and leaks repaired. For a satisfactoryinstallation, the system must be leak tight.

(m)After the final leak test, refrigerant lines ex-posed to high ambient conditions should beinsulated to reduce heat pick-up and preventthe formation of flash gas in the liquid lines.Suction lines should be insulated, if exposed,to prevent condensation.

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Installation, Plumbing

Good practice requires the following:

(a) Lines should be sloped adequately to drain bygravity any water accumulated from condens-ing, defrosting, or cleaning operations.

(b) All plumbing connections should be made inaccordance with local plumbing codes.

(c) Condensate lines from refrigerated fixturesmust be trapped and run to an open drain.They must not be connected directly to thesewer system.

IF THE SYSTEM IS WATER-COOLED:

(d) Water pipe sizes should be adequate to pro-vide the required flow at the lowest inlet pres-sure anticipated.

(e) Control devices such as solenoid valves, modu-lating valves, or hand valves that could causehydraulic hammer should be protected by astand-pipe and air pocket to absorb this shock.Electrical or pressure operated water controlvalves should be installed between the watersupply and the condenser inlet—never be-tween the condenser and the drain. If watersupply pressure is excessive, a pressure re-ducing valve must be used since the allowableworking pressure of water valves is normally150 psig. Pressures above this level can alsocause damage to the condenser.

(f) The water pump must be checked for rotationand proper performance.

(g) Check for water leaks.

Evacuation

A good high vacuum pump should be connected toboth the low and high side evacuation valves withcopper tube or high vacuum hoses (1/4” ID mini-mum). If the compressor has service valves, theyshould remain closed. A high vacuum gauge ca-pable of registering pressure in microns should beattached to the system for pressure readings.

A shut off valve between the gauge connectionand the vacuum pump should be provided to allowthe system pressure to be checked after evacua-tion. Do not turn off vacuum pump when con-nected to an evacuated system before closingshut off valve.

The vacuum pump should be operated until apressure of 1,500 microns absolute pressure isreached—at which time the vacuum should bebroken with the refrigerant to be used in the systemthrough a drier until the system pressure risesabove “0” psig.

Repeat this operation a second time.

Open the compressor service valves (if supplied)and evacuate the entire system to 500 micronsabsolute pressure.

Raise the pressure to 2 psig with the refrigerantand remove the vacuum pump.

Under no conditions is the motor-compressor to bestarted or operated while the system is under ahigh vacuum. To do so may cause serious dam-age to the motor windings because of the reduceddielectric strength of the atmosphere within themotor chamber.

Check-Out and Start Up

After the installation has been completed, thefollowing points should be covered before thesystem is placed in operation.

(a) Check electrical connections. Be sure they areall tight.

(b) Observe compressor oil level before start-up.The oil level should be at or slightly above thecenter of the sight glass. Use only Copelandapproved oil.

(c) Remove or loosen shipping retainers undermotor-compressors. Make sure hold down nutson spring mounted compressors are nottouching the compressor feet.

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(d) Check high and low pressure controls, watervalves, pressure regulating valves, oil pres-sure safety controls, and all other safety con-trols, and adjust if necessary.

(e) Check thermostat for normal operation.

(f) Suitable tags or other means should be pro-vided to indicate refrigerant used in the sys-tem. Some Copeland condensing unit name-plates have two detachable corner tabs. Oneshould be removed so that the nameplateindicates the refrigerant used.

(g) Wiring diagrams, instruction bulletins, etc.,attached to motor-compressors or condensingunits should be read and filed for future refer-ence.

(h) Make the proper refrigerant connections andcharge the unit with the refrigerant to be used.Weigh the refrigerant drum before charging soan accurate record can be kept of the weight ofrefrigerant put in the system. If the refrigerantmust be added to the system through thesuction side of the compressor, charge invapor form only. Liquid charging must be donein the high side only.

(i) Observe system pressures during chargingand initial operation. Do not add oil while thesystem is short of refrigerant, unless oil level isdangerously low.

(j) Continue charging until system has sufficientrefrigerant for proper operation. Do not over-charge. Remember that bubbles in a sightglass may be caused by a restriction as wellas a shortage of refrigerant.

(k) Do not leave unit unattended until the systemhas reached normal operating conditions andthe oil charge has been properly adjusted tomaintain the oil level at the center of the sightglass.

Operational Check-Out

After the system has been charged and has oper-ated for at least two hours at normal operating

conditions without any indication of malfunction, itshould be allowed to operate over-night on auto-matic controls. Then a thorough recheck of theentire system operation should be made as fol-lows:

(a) Check compressor head and suction pres-sures. If not within system design limits, deter-mine why and take corrective action.

(b) Check liquid line sight glass and expansionvalve operation. If there are indications thatmore refrigerant is required, leak test all con-nections and system components and repairany leaks before adding refrigerant.

(c) When applicable, observe oil level in compres-sor crankcase sight glass, and add oil asnecessary to bring level to center of the sightglass.

(d) Thermostatic expansion valves must bechecked for proper superheat settings. Feelerbulbs must be in positive contact with thesuction line. Valves with high superheat set-tings produce little refrigeration and poor oilreturn. Too little superheat causes low refrig-eration capacity and promotes liquid sluggingand compressor bearing washout. Liquid re-frigerant must be prevented from reaching thecrankcase. If proper control cannot be achievedwith the system in normal operation, a suctionaccumulator must be installed in the suctionline just ahead of the compressor to preventliquid refrigerant from reaching the compres-sor.

(e) Using suitable instruments, carefully checkline voltage and amperage at the compressorterminals. Voltage must be within 10% of thatindicated on the compressor nameplate. Ifhigh or low voltage is indicated, notify thepower company. The current normally shouldnot exceed 120% of the nameplate rating. Ifamperage draw is excessive, immediately de-termine the cause and take corrective action.On three phase motor-compressors, check tosee that a balanced load is drawn by eachphase.

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(f) All fan motors on air cooled condensers, evapo-rators, etc. should be checked for proper rota-tion. Fan motor mounts should be carefullychecked for tightness and proper alignment. Ifbelt drives are used, check the belt tension. Allmotors requiring lubrication should be oiled orgreased as necessary.

(g) Check defrost controls for initiation and termi-nation setting, and length of defrost period.Check crankcase heaters if used.

(h) Check winter head pressure controls for pres-sure setting.

(i) Check crankcase pressure regulating valves,if any, for proper setting.

(j) Adjust water valves on water cooled systemsto maintain desired condensing temperatures.Check water pumps for proper rotation.

(k) Install instruction card and control system dia-gram for use of store manager or owner.

Identification

Each refrigerated fixture and cooler coil should benumbered starting at No. 1. These numbers shouldbe not less than ½” in height and should bestenciled or marked neatly on the fixture in aninconspicuous location easily available to the ser-viceman. The compressors or condensing unitsserving the fixtures should be marked with thenumbers of the cases and coils served with figuresnot less than 1” in height.

Service Record

A permanent data sheet should be prepared oneach installation, with a copy for the owner and theoriginal for the installing contractor’s files. If an-other firm is to handle service and maintenance,additional copies should be prepared as neces-sary.

The form of the data sheet may vary, but a com-plete record of sizes and identification of all com-ponents used in the installation, together with anypertinent information should be included. Follow-ing is a suggested check-off list:

(a) Compressor manufacturer, model, and serialnumber.

(b) Equipment manufacturer, model, and serialnumber.

(c) Design operating temperatures.

(d) Condensing unit model, and serial number. (Ifpackage condensing unit.)

(e) If remote condenser, type, manufacturer,model, fan data.

(f) Refrigerant and weight of charge.

(g) Electrical service, volts, cycles, phase, wiresize.

(h) Control circuit, voltage, fuse size.

(i) Contactor or starter, manufacturer, model, size,part number.

(j) Compressor motor protection, type, size, partnumber.

(k) Data on capacitors, relays, or other electricalcomponents.

(l) Pressure control, type, size, model number,setting.

(m)Oil pressure safety control, type, model number.

(n) Defrost control, type, manufacturer, modelnumber, setting.

(o) Data on miscellaneous refrigeration compo-nents such as pressure controls, winterizingcontrols, oil separators, crankcase heaters,solenoids, valves, etc.

(p) Liquid line drier, manufacturer, size, modelnumber, connections.

(q) Schematic diagram of refrigerant piping.

(r) Final settings on all pressure, regulating, andsafety controls.

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FUNDAMENTALS OF EVACUATION ANDDEHYDRATION

Although millions of dollars have been spent onrefrigeration research, many of the reactions in-side air conditioning and refrigeration systems arestill a mystery. We do know that the presence ofmoisture, heat, and oxygen under certain condi-tions can result in many forms of system damage.Corrosion, sludging, copper plating, oil break-down, carbon formation, and eventual compres-sor failure can be caused by these contaminants.

The absence of any one of the three, or its reduc-tion to an acceptable level can greatly extendcompressor life and slow down harmful reactions.If all three can be controlled, then a sound founda-tion has been made for a trouble free installation.

Copeland compressors are carefully tested todetermine limits within which operation is possiblewithout creating excessive heat in the compres-sor. But under the best operating conditions, heatis going to be produced as a natural consequenceof compression of the refrigerant gas. Dischargetemperatures in excess of 200°F. are unavoidable.Therefore, major efforts must be directed at pre-venting moisture and air from entering the system.

Moisture In A Refrigeration System

Moisture exists in three forms; as a solid when it isfrozen into ice, as liquid water, and as a vapor orgas. It is extremely rare that moisture will enter arefrigeration system in the form of ice or water. Itis the invisible water vapor that exists in the airaround us that creates the real hazard.

The ability of air to hold water vapor increases withthe temperature of the air. On a hot, humidsummer day, the air may be actually loaded withmoisture. Relative humidity is the term commonlyused to express the percentage of saturation, thatis, the existing moisture content of the air ex-pressed as a percentage of the maximum mois-ture that the air could contain at a given tempera-ture.

The relative humidity determines the dew point, orthe temperature at which moisture will condenseout of the air. Condensation occurs on the outside

of a cold glass of water in a warm room, and it canoccur in exactly the same fashion inside a coldevaporator which has been opened and exposedto the atmosphere.

Despite the fact that water vapor exists as part ofthe air around us, it acts quite independently of theair. Vapor pressure is independent of air pressure,and its speed of movement is astonishing. Thismeans that water vapor cannot be stopped by airmovement.

Obviously it is impossible to prevent water vaporfrom entering the system anytime it is opened tothe atmosphere. However, if the temperature ofthe exposed part of the system is above the dewpoint, or if the time of exposure is short, the amountof moisture actually entering the system will besmall. If a new drier is installed in the liquid lineeach time the system is opened for maintenance,the drier will normally have sufficient capacity tolower the moisture in the system to a safe level.

However, at the time of original installation, orafter exposure for long periods during mainte-nance, the amount of moisture in the system maybe greater than a drier’s effective capacity. Insuch cases, evacuation is the only effective meansof removing large quantities of moisture from thesystem, and to successfully dehydrate a systemby evacuation, pressures within the system mustbe reduced to levels which will cause the trappedmoisture to vaporize.

Air In A Refrigeration System

The air we breathe is primarily composed ofnitrogen and oxygen. Both elements remain in agaseous form at all temperatures and pressuresencountered in commercial refrigeration and airconditioning systems. Therefore, although thesegases can be liquified under extremely low tem-peratures, they may be considered as non-con-densable in a refrigeration system.

Scientists have discovered that one of the basiclaws of nature is the fact that in a combination ofgases, each gas exerts its own pressure indepen-dently of others, and the total pressure existing ina system is the total of all the gaseous pressurespresent. A second basic characteristic of a gas is

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that if the space in which it is enclosed remainsconstant, so that it cannot expand, its pressure willvary directly with the temperature. Therefore, if airis sealed in a system with refrigerant, the nitrogenand oxygen will each add their pressure to thesystem pressure, and this will increase as thetemperature rises.

Since the air is non-condensable, it will usuallytrap in the top of the condenser and the receiver.During operation the compressor discharge pres-sure will be a combination of the refrigerant con-densing pressure plus the pressure exerted by thenitrogen and oxygen. The amount of pressureabove normal condensing pressures that mayresult will depend on the amount of trapped air, butit can easily reach 40 to 50 psig or more. Any timea system is running with abnormally high headpressure, air in the system is a prime suspect.

Nitrogen is basically an inert gas and does noteasily enter into chemical reactions. Oxygen,however, is just the reverse, and at the slightestopportunity will combine with other elements. Rust,corrosion, and burning are all common oxidationprocesses.

In the refrigeration system, oxygen and moisturequickly join in a common attack on the refrigerantand oil, and can cause corrosion, copper plating,acid formation, sludging, and other harmful reac-tions. Tests have shown that in the presence ofheat, the combination of air and moisture is farmore apt to cause breakdown of the refrigerantand oil mixture than greatly increased amounts ofmoisture alone.

Pressure - Temperature - EvaporatingRelationships

Anyone familiar with refrigeration knows that re-frigerants follow a definite fixed pressure-tem-perature relationship, and that at a given pressurethe refrigerant will boil or vaporize at a corre-sponding saturation temperature. Water followsexactly the same pattern, and this is the basis fordehydration by evacuation.

The pressure which determines the boiling pointsof refrigerants and water is absolute pressure,normally expressed in terms of psia, which is

defined as the pressure existing above a perfectvacuum.

The atmosphere surrounding the Earth is com-posed of gases, primarily oxygen and nitrogen,extending many miles above the surface of theEarth. The weight of that atmosphere pressingdown on the Earth creates the atmospheric pres-sure we live in. At a given point, the atmosphericpressure is relatively constant except for minorchanges due to changing weather conditions. Forpurposes of standardization and as a basic refer-ence for comparison, the atmospheric pressure atsea level has been universally accepted, and thishas been established at 14.7 pounds per squareinch, which is equivalent to the pressure exertedby a column of mercury 29.92 inches high.

At very low pressures, it is necessary to use asmaller unit of measurement since even inches ofmercury are too large for accurate reading. Themicron, a metric unit of length, is commonly usedfor this purpose, and when we speak of microns inevacuation, we are referring to absolute pressurein units of microns of mercury. Relationships ofthe various units of measurement are as follows:

1 pound per sq. in. = 2.03 inches mercury1 inch mercury = .491 pounds per sq. in.1 inch mercury = 25,400 microns mercury1 inch = 25,400 microns1 millimeter = 1,000 microns1 micron = .001 millimeter

The refrigeration serviceman’s bourdon tube gaugereads 0 pounds per square inch when not con-nected to a pressure producing source. Thereforethe standard relationship has been establishedthat absolute pressure is equal to gauge pressureplus 14.7 psi. Pressures below 0 psig are actuallynegative readings on the gauge, and are referredto as inches of vacuum. The gauge is calibrated inthe equivalent of inches of mercury.

Factors Affecting Vacuum Pump Performance

A vacuum pump suitable for refrigeration workmust not only be capable of pulling a high vacuum,but must be capable of maintaining that vacuum onthe system for prolonged periods. As moist air ispumped through the vacuum pump, the moisture

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The above table clearly illustrates the reduction of the boiling point of water with a reduction of pressure.It is clear that at normal room temperatures, dehydration by evacuation requires pressures below 0.40psia, which means a corresponding vacuum reading at sea level of 29.2 inches of mercury. At pressuresabove that, boiling simply would not take place. From a practical standpoint, much lower pressures arenecessary to create a temperature difference to the boiling water so that heat transfer can take place,and also to offset pressure drop in the connecting lines, which is extremely critical at very low pressures.Pressures from 1,500 to 2,000 microns are required for effective dehydration, and equipment to accom-plish this is normally described as being designed for high vacuum work. Heat should be applied tosystems which are known to contain free water to aid in evacuation.

It is important to remember that gauge pressures are only relative to absolute pressure. The table showsrelationships existing at various elevations assuming that standard atmospheric conditions prevail. Ob-viously, a given gauge pressure at varying elevations may actually reflect a wide variation in actualabsolute pressures.


will seek to condense in the vacuum pump oilsump, and once the oil is saturated, water vaporescaping from the oil may prevent the pump fromachieving a high vacuum. Unless the pump isspecifically designed to prevent this condition, theoil may become saturated before one evacuationjob is completed.

In order to prevent condensation, some vacuumpumps have a vented exhaust or gas ballastfeature. Basically this involves allowing a smallbleed of atmospheric air to enter the second stageof a two stage pump, or the discharge chamber ofa single stage pump prior to the discharge stroketo prevent condensation of water during compres-sion.

Since reciprocating pumps lose efficiency at vacu-ums greater than 27 inches of mercury, rotarypumps are primarily used for high vacuum work.Single stage vacuum pumps are available whichare capable of pulling a very high vacuum, but ingeneral they are vulnerable to oil contamination,and if the exhaust is vented to protect the oil, thenthe pump’s efficiency is reduced. Although singlestage pumps may be quite satisfactory for smallsystems, for best high vacuum performance inrefrigeration usage a two stage vacuum pump withgas ballast on the second stage is recommended.

Even at extremely low pressures, it is essentialthat the system to be evacuated is at a tempera-ture high enough to insure boiling of any water tobe removed. With pressures of 2000 microns andbelow, normal room temperatures of 70°F. to80°F. are adequate. Evacuation of temperaturesbelow 50°F. is not recommended.

If a great deal of moisture must be removed froma system by the vacuum pump, the oil may becomesaturated with moisture despite the gas ballastfeature or the best pump design. Once this hasoccurred, the only solution is to change the oil inthe vacuum pump. Even with the best vacuumpump, frequent oil changes are necessary to main-tain efficiency. It is recommended that the oil bechanged before each major evacuation.

If there is any possibility that large amounts ofwater may be trapped in a system, the lines shouldbe blown out with dry nitrogen prior to attaching the

vacuum pump. This will not only aid in prolongingthe life of the pump, it will materially decrease thetime required to evacuate the system. If it is knownthat a system is saturated with water, for exampleafter the rupture of tubes in a water cooled con-denser, a special low temperature moisture trapshould be installed in the suction line ahead of thevacuum pump intake. Suitable traps are availablefrom vacuum pump manufacturers.

One factor that is not fully appreciated by mostservicemen is the critical nature of the pressuredrop that occurs due to restrictions in the lineduring evacuation. For field evacuation with por-table vacuum pumps, lines connecting the vacuumpump to the system should be a minimum of ¼”I.D. on small systems, and on larger systems atleast ½” I.D. copper tubing should be used. Evacu-ating valves are recommended for every system.These should be installed in both the suction andliquid lines, and should be at least as large as theconnecting lines. The typical serviceman’s mani-fold and charging hose will cause sufficient restric-tion to prevent a high vacuum being reached, andcompressor service valves are also unsatisfactoryfor high vacuum work. If restrictions exist in theconnecting lines, gauges at the vacuum pump willreflect pump pressure, but will not give a truepicture of pressures in the system.

The speed with which a system may be evacuateddepends on both the displacement of the vacuumpump and the size of the connecting lines andfittings. A good high vacuum pump has a very highpumping efficiency down to absolute pressures of1,000 microns and below, possibly as high as 85%to 90% or more. This means that a vacuum pumpwith 1 CFM displacement may still be capable ofpumping up to .9 CFM with a suction pressure of1,000 microns and discharging to atmosphere.

However, a vacuum pump’s performance can begreatly reduced by the size of connecting lines andfittings. In the low or medium vacuum range, thismay not greatly affect a pump’s efficiency, but atpressures below 5,000 microns the pump’s netcapacity can decrease rapidly. The followingcomparison is based on one pump manufacturer’scatalog information on pumping speed of rotaryvacuum pumps.

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It is interesting to note that more efficiency can begained by increasing the connecting line size on a1 CFM pump from ¼” I.D. to a larger size than canbe gained by putting a 5 CFM pump on the same¼” connection.

Calculations to determine pull down time are quitecomplicated, since the pump’s efficiency changeswith the reduced pressure, and the size and lengthof the connecting lines may greatly affect theperformance of a given pump. The following esti-mate of pull down time is based on onemanufacturer’s catalog data, but because of theassumptions that must be made in the calculation,the figures are at best an approximation.

ESTIMATED TIME REQUIRED FOR SYSTEMPULL DOWN

based on 5 cubic feet internal volumeThe above table provides a good comparison ofrelative pump performance. It is quite clear that ifa connecting line no larger than ¼” I.D. is to beused, there is little to be gained by going to a largervacuum pump. For large systems it is obvious thatboth a good sized vacuum pump and a largeconnecting line are necessary if the required timeis to be held to a minimum. The pull down time will

vary directly with the internal volume of a givensystem, so for smaller systems the 1 CFM pumpmay be perfectly satisfactory.

Measurement of Vacuum

As indicated earlier, the refrigeration serviceman’sgauge reads pressure only in relation to absolutepressure, and a given gauge reading may cover awide range of actual pressures. For this reason,and also because the ordinary bourdon tube com-pound gauge is not designed for the extremeaccuracy required in evacuation work, a specialvacuum gauge is required for high vacuum read-ings.

For accurate pressure readings in the micronrange for refrigeration use, a thermocouple vacuumgauge is recommended. This type of gauge isrelatively inexpensive, easy to operate, ruggedenough for field use, and requires little or nomaintenance. The advantage of this gauge wheremoisture may be encountered in a system is thatit measures not only the pressure due to residualgases, but also the pressure contributed by anywater vapor remaining in the system. The McLeodtype gauge is widely used in laboratory work, andis highly accurate for readings where moisture isnot a factor, but it is not recommended for use inrefrigeration work since it will not measure thepressure due to water vapor.

Triple Evacuation

In order to insure a complete evacuation, Copelandrecommends a triple evacuation, twice to 1,500microns and the final time to 500 microns. Thevacuum should be broken to 2 psig each time withthe same type of refrigerant to be used in thesystem.

It is quite possible that the original evacuation, ifnot continued for a sufficient period of time may notcompletely remove all of the air and moisture fromthe system. Breaking the initial vacuum with dryrefrigerant allows the fresh refrigerant to absorband mix with any residual moisture and air, and thesucceeding evacuation will remove a major portionof any remaining contaminants. If for example,each evacuation removed only 98% of the con-tents of the system, and any remaining contami-

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nants mixed thoroughly with the refrigerant used tobreak the vacuum, after the triple evacuation theremaining contaminant percentage would be 2% x2% x 2% or .0008%. The residual contaminantshave been reduced to such a low level they nolonger are a danger to the system. This illustrateswhy triple evacuation is increasingly important ifthe vacuum pump is not of the highest efficiency,or if the evacuation time is not adequate to insurecomplete evacuation.

Many manufacturers use process pressures of 50to 100 microns. However, in field evacuation,pressures in this range are very difficult to reach,particularly if refrigerant has been allowed to mixwith oil in the system. The refrigerant will escapefrom the oil very slowly, and the time required toreach such low pressures might be quite unrea-sonable. The triple evacuation method to a pres-sure of 500 microns is practical under field condi-tions, and represents a specification that can bemet.

For manufacturers having process equipment, theuse of dry air with a dew point below -60°F. in placeof refrigerant for dehydration in connection with atriple evacuation to the pressures described aboveis also highly recommended.

To evacuate a system properly requires time andcare. Any slight carelessness in protecting thesealed system can undo all the precautions takenpreviously. But the slight extra effort required tomake an evacuation properly and completely willpay big dividends in reduced maintenance andtrouble free operation.

BRAZING CONNECTIONS ON COPELAWELDMOTOR-COMPRESSORS

Suction and discharge line connections toCopelaweld motor-compressors are normally madeby brazing the refrigerant lines directly into stubtubes on the compressor with a silver brazing alloy.Occasionally the joint between the stub tube andthe steel shell is damaged by overheating duringfactory or field installation when the refrigerant lineconnections are made. This type of damage canbe avoided by proper care during the brazingoperation.

The connection between the stub tube and theshell is made with a 35% silver brazing alloy whichhas a melting range of 1125°F. to 1295°F. Thetemperature of this joint must be kept below thisrange during the line brazing operation to avoiddamage.

Figure 111 illustrates a typical suction line connec-tion. The torch flame should be used primarily onthe refrigerant line, with only enough heat appliedto the stub tube to make the connection properly.Heat will be conducted into the joint area from therefrigerant line. The torch fame should have agreenish “feather” extending from the tip of theinner blue cone as illustrated in Figure 112. Heatshould be applied to both sides of the tube, and theflame should be moved continuously in a circularmotion to distribute the heat, and prevent over-heating of the tubing. Compressors with dam-aged joints usually show evidence of the torchflame having been allowed to burn directly on thecompressor shell and the stub tube-shell joint.

Copeland recommends that a low melting pointalloy such as Easy-Flo or Easy-Flo 45 be used inmaking the line joint rather than a higher meltingpoint alloy such as Sil-Fos. The heat necessary tomake a Sil-Fos joint is somewhat greater thanrequired for Easy-Flo, making it more difficult to

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avoid overheating. Another advantage of a lowertemperature brazing alloy is the reduced anneal-ing effect which takes the place, thus resulting ina stronger joint.

To assure a sound, leak tight tubing connectionwithout overheating, the surfaces must be prop-erly cleaned and a suitable flux must be used. Alow temperature brazing flux that is fully liquid andactive below the flow point of the silver brazingalloy is required. Only the male connection shouldbe fluxed, and only enough flux should be used toadequately cover the surface. Excess flux allowedto enter the system can cause starting failures onPSC motors, plug filters and valves, and maycause other complications due to chemical reac-tions.

INSTALLATION OF SUCTION AND DISCHARGELINE VIBRATION ABSORBERS

In order to prevent the transmission of noise andvibration from the compressor through the refrig-

eration piping, vibration eliminators are often re-quired in the suction and discharge lines. On smallunits where small diameter soft copper tubing isused for the refrigerant lines, a coil of tubing mayprovide adequate protection against vibration. Onlarger units, flexible metallic hose is frequentlyused.

Metallic vibration absorbers should be selected tohave the same or greater internal diameter thanthe connecting piping. Because of the convolu-tions of the inner wall of the absorber, excessiverefrigerant gas velocity can cause whistling andnoise problems.

Unless properly installed, stress resulting from linemovement may cause failure of the vibration ab-sorber, and possibly can lead to line breakage.Because of its construction, a metallic vibrationabsorber can easily adjust to movement in a radialdirection, but it must not be subjected to stress ineither compression or extension. Some manufac-turers recommend using two vibration absorbersat right angles, but normally this is not necessaryon Copeland compressors.

Copeland recommends installation parallel to thecrankshaft, as close to the compressor as pos-sible. The starting torque of the motor will tend torock the compressor from side to side when start-ing, and mounting parallel to the crankshaft willallow the absorber to easily adjust to the move-ment.

Vibration absorbers may be installed in a verticalposition if the joints are sealed against trapping of

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condensation which might damage the bellowsdue to freezing. Filling of the joints with soft solderas a means of sealing is recommended. Flexiblemetal hoses are available with a neoprene jacketwhich protects the absorber against any possibledamage from condensation or moisture.

Installation of an angle 45° from the vertical andparallel to the crankshaft is acceptable, althoughhorizontal or vertical installation is preferred. A 45°angle installation at right angles to the compressorcrankshaft can actually act as a brace, causingcompression stress, and is not acceptable.

Installation in the horizontal plane at right angles tothe crankshaft is not acceptable, since compres-sor movement would tend to either compress orextend the absorber, and early failure of the ab-sorber or connecting fittings could result.

The line connected to the end of the absorberopposite the source of vibration should be firmlyanchored to a solid member. No movement willthen be transmitted into the refrigerant lines be-yond. Where a vertical or 45° mounting is used,the piping must be arranged so that sufficientallowance for movement is made. As a convenientmeans of checking the installation, a springmounted compressor should be free to bottomsolidly on the mounting pad or mounting snubberwithout stressing the absorber. The refrigerantlines should be in proper alignment prior to instal-lation of the absorber, and sufficient space shouldbe allowed so that it can be installed without beingeither stressed or compressed.

Internal joints of metallic vibration absorbers areoften made up with a brazing compound which hasa melting point of approximately 1,300°F. In orderto avoid damage to the internal joints, line connec-tions should be made with a silver solder alloyhaving a melting temperature below 1,200°F.

TYPICAL INSTALLATION SPECIFICATIONS

On large field installed refrigeration and air condi-tioning systems, it is advisable to have a writtenspecification covering the work to be done and theresponsibilities of each party. The specification isan aid in assuring a clear understanding of thecontractor’s responsibility prior to the start of the

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job, so that disputes and disagreements may beeliminated.

Specifications may vary from a short paragraphcovering the scope of the work to a detailed

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Typical Specification

Large Commercial Refrigeration and Air Conditioning Installation

1. Definition of Terms

1.1 “Contractor” shall mean the refrigeration installation contractor.

1.2 “Owner” is .

1.3 “Manufacturer” shall mean the company or companies which will supply various equipment suchas fixtures, compressors, coils, etc.

1.4 “Refrigeration Installation” shall mean the necessary labor and all parts and accessoriesnecessary to complete the work outline in this specification.

2. Scope of Work

2.1 These specifications are intended to cover the installation of compressors, condensers, coils,condensing units, fixtures, and all other fittings, devices, and accessories required to completethe refrigeration systems as shown or called for on the refrigeration plans and schedules. Theomission from these specifications or from the refrigeration plans and schedules of expressreference to any parts necessary for the complete installation is not to be construed as releasingthe contractor from responsibility for furnishing such parts.

2.2 For details of installation refer to the fixture plan, refrigeration schedule, floor plan, plumbing plan,electric plan, air conditioning, heating, and ventilating plan, manufacturer’s installation instruc-tions, and to applicable codes and ordinances.

2.3 The Contractor shall furnish and install any necessary refrigerant piping, fittings, vibrationeliminators, line valves, solenoid valves, crankcase pressure regulating valves, thermostaticexpansion valves, dehydrators, strainers, sight glasses, moisture indicators, refrigerant, oil,filters, insulation and all fittings and accessories necessary to make a complete installationunless otherwise specified, together with all labor required to complete the installation andperform the service covered by this specification. The Contractor is responsible for unloading,assembling, and installing all fixtures, coolers, coils, compressors, condensing units, airconditioners, condensers, and other refrigeration equipment unless otherwise specified. TheContractor shall also arrange for the removal of crating and packing materials, and shall leavethe uncrating area and the compressor room clean and neat.

description of the work to be done. The followingspecification is typical of the type frequently usedon supermarket or other large commercial refrig-eration installations, and is readily adaptable todifferent types of applications.


2.4 The Contractor shall familiarize himself with the project, and shall cooperate with othercontractors doing work on the building. If any conflict, interference, or discrepancies come to theattention of the contractor, he shall notify the owner immediately before proceeding any furtherwith the installation.

2.5 No additional payment over and above the contract price will be made unless the Contractorreceives a written order by the Owner or his representative for the addition.

2.6 Equipment and services shall be furnished as follows:

To Be Furnished ByOwner Contractor Others

Refrigerated fixturesCoils for coolersAir conditioning unitsAir conditioning temperature controlsAir cooled condensersCompressorsCondensing unitsRefrigeration system controlsCoolers & freezers (walk in)Coolers & freezers (reach in)Ventilation and exhaust fans and controlsCooling tower and controlsPlumbingSheet metal, duct work, dampers, etc.Motor starters and protectorsElectrical wiring, disconnect switchesand connections

3. Fees, Permits, Licenses, and Insurance

3.1 All necessary permits and licenses incident to the work and required by local ordinance shall besecured and paid for by the contractor. All equipment shall be installed in strict compliance withall local building codes and ordinances.

3.2 The Contractor shall not commence work under this contract until he has obtained all theinsurance required hereunder, and has filed certificates to that effect with the Owner. TheContractor shall indemnify and hold harmless the Owner for any and all claims, suits, losses,damages, or expenses on account of bodily injury, sickness, disease, death, and propertydamage as a result of the Contractor’s operations, acts, omissions, neglect or misconduct inconnection with this project. Insurance coverage shall include but is not limited to

(a) Contractor’s Public Liability Insurance(b) Contractor’s Contingent Liability Insurance(c) Property Damage Insurance(d) Automotive Public Liability Insurance(e) Automotive Property Damage Insurance

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4. Refrigerant Piping Materials

4.1 Unless otherwise specified, all refrigeration piping shall be refrigeration grade Type L or Type Khard drawn degreased sealed copper tubing. Alternate proposals may be submitted for the useof Type L refrigeration grade soft copper tubing for long underfloor runs only providing runs arestraight and free from kinks and bends.

4.2 Extreme care shall be taken to keep all refrigerant piping clean and dry. It shall be kept sealedexcept when cutting or fabricating. Each length shall be inspected and swabbed with a clothsoaked in refrigeration oil if any dirt, filings, or visible moisture are present.

4.3 All sweat-type fittings shall be wrought copper or forged brass. All elbows and return bends shallbe of the long radius type. If flare fittings are required, they shall be of the frost proof type, (excepton connections not subject to condensation), and constructed of forged brass. Soldered jointsare preferred and shall be used wherever practical.

5. Refrigerant Piping Installation

5.1 Tubing shall be installed in a neat, workmanlike manner with horizontal runs sloped toward thecompressor at a rate of 1” per 20’. All lines shall be supported at intervals of not more than 8’and suitably anchored. Rubber grommets shall be used between tubing and clamps to preventline chafing.

5.2 Where vertical risers of more than 5 feet occur in a suction line, the riser shall be trapped at thebottom.

5.3 Where a branch suction line enters a main suction line it shall enter at the top. Piping shall bearranged so refrigerant or oil cannot drain from the suction line into the coil.

5.4 Individual fixture or unit suction and liquid lines shall be of the size recommended by theManufacturer as shown in the applicable installation and service instructions. Liquid and hot gasrefrigerant lines shall be sized in accordance with good industry practice to avoid excessivepressure drops. Branch and main suction lines shall be sized to maintain adequate velocities toproperly return oil to the compressor under minimum load conditions at the lowest saturatedsuction pressure to be expected.

5.5 All joints in the compressor discharge line shall be brazed with a suitable high temperature silversolder alloy containing not less than 15% silver. Use only a suitable silver solder alloy on allcopper to copper connections in the suction line and liquid line. At any copper to brass joint wheredamage could occur from excess heat use 95/5 solder. Use a solder with at least 35% silvercontent on all copper to steel, brass to steel, or steel to steel joints. During the brazing operation,dry nitrogen must be bled through the piping at very low pressure to prevent oxidation and scaling.

5.6 In order to avoid damage to the internal Silfos joints in vibration eliminators, line connections tovibration eliminators are to be made with a silver solder alloy such as Easy-Flo having a meltingtemperature of 900°F. to 1,200°F. (well below the 1,300°F. melting point of Silfos).

5.7 To prevent contamination of the line internally, limit the soldering paste or flux to the minimumrequired. Flux only the male portion of the connection, never the female.

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5.8 Suction lines from low temperature cases shall be insulated where run below the floor level. Allexposed suction lines, both low and medium temperature, shall be insulated as necessary toprevent condensation.

5.9 Insulation shall be of the cellular type such as Armstrong “Armaflex” or equal, shall fit the tubingsnugly, and shall be applied and sealed in accordance with the Manufacturer’s instructions.

5.10 The refrigerant piping shall be adequately protected. Permanent guards shall be installed asrequired to protect the piping and fittings from damage. Metal pipe sleeves shall be providedwhere tubing passes through a concrete wall or floor, and the space around the tubing shall befilled with a mastic insulating compound.

5.11 Arrange the piping so that normal inspection and servicing of the compressor and otherequipment is not hindered. Do not obstruct the view of the crankcase oil sight glass, or run pipingso that it interferes with removal of the compressor or other components.

5.12 Tubing installed in trenches or conduit under the floor must be level to prevent oil trapping. Guardagainst deformation or damage from trucks carrying heavy loads, or cement being poured.

6. Installation of Accessories

6.1 Vibration eliminators shall be installed in the suction and discharge lines of all compressors withspring or flexible mounting. The vibration eliminator must be applied according to the Manufacturer’srecommendations. For Copelametic compressors, the vibration eliminator should be mountedparallel to the crankshaft, as close to the compressor as possible. Installation in a horizontal planeat right angles to the crankshaft is not acceptable, since the resulting stress from compressormovement may cause failure of the vibration absorber. If installed in a vertical position, theeliminator joints must be sealed against dripping from condensation to protect from freezing.

6.2 A solder type combination liquid sight glass and moisture indicator shall be installed in eachsystem and located for easy visibility.

6.3 If liquid line driers are not otherwise specified, they shall be of the filter-drier type, and of the sizerecommended by the Manufacturer. Drier cartridges shall not be installed until the secondevacuation has been completed.

6.4 Two evacuation fittings are necessary. One should be in the suction line at the inlet side of thesuction line filter, and one should be in the liquid line at the outlet side of the filter-drier. If properlyvalved, the connection in the liquid line may serve as a charging valve. After evacuation andcharging, the fittings are to be capped or removed. Connections should be at least 3/8” andpreferably ½” in size.

6.5 A permanent suction line filter shall be installed in each compressor suction line. A pressurefitting must be provided ahead of the filter, preferably in the shell, to facilitate checking thepressure drop. If the pressure drop across the filter is in excess of 1 psig after the initial 24 hoursof operation, the suction line filter cartridge shall be replaced, or if the filter is of the sealedpermanent type, the filter shall be replaced.

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7. Drain Connections

7.1 Unless otherwise specified, condensate drains from coils and cases to the floor drain will be theresponsibility of the Contractor. No drain line shall be smaller than the coil drain pan connection.All drain lines shall be hard copper tubing except for those in reach-in coolers. Lines should besloped adequately to drain by gravity any water accumulated from condensing, defrosting, orcleaning operations. All condensate lines from refrigerated fixtures must be trapped and run toan open drain. They must not be connected directly to the sewer system. If necessary forcleaning, threaded unions shall be provided in the most accessible location near the fixture.

8. Testing, Evacuation, and Charging

8.1 The Contractor shall notify the Owner 24 hours in advance of any test so that the Owner and/or Manufacturer’s representative may be present for the test if desired.

8.2 When the refrigeration connections have been completed, the system shall be tested at aminimum of 150 psig with the compressor suction and discharge valves closed, and all othervalves in the system open. (If local codes require higher test pressures, such codes must becomplied with). Leak testing shall be performed with an electronic leak detector, unless the useof a halide torch is specifically authorized by the Owner. Refrigeration piping will not beacceptable unless it is gas tight. If any leaks are found, isolate the defective area, discharge thegas and repair the leaks, and then repeat the test. When testing has been completed, releaseall pressure freely to the atmosphere.

8.3 The system shall be evacuated with a vacuum pump specifically manufactured for vacuum duty,having a capability of pulling a vacuum of 50 microns or less. Evacuation of the system mustnever be done by the use of the refrigeration compressor. The pump should be connected toboth the low and high side evacuation valves with copper tube or high vacuum hoses. (1/4” I.D.minimum). The compressor service valves should remain closed. A high vacuum gauge capableof registering pressure in microns should be attached to the system for pressure readings.Hermetic or accessible-hermetic motor compressors must not be operated during evacuationbecause of the reduced dielectric strength of the atmosphere within the motor chamber. Tocheck system pressure, a hand valve must be provided between the pressure gauge and thevacuum pump which can be closed to isolate the system and check the pressure.

8.4 Evacuate each system to an absolute pressure not exceeding 1,500 microns. Install a drier ofthe required size in the liquid line, open the compressor suction and discharge valves, andevacuate to an absolute pressure not exceeding 500 microns. Leave the vacuum pump runningfor not less than two hours without interruption. Raise the system pressure to 2 psig withrefrigerant, and remove the vacuum pump.

8.5 Refrigerant shall be charged directly from the original drums through a combination filter-drier.Each drier may be used for a maximum of three cylinders of refrigerant, and then must bereplaced with a fresh drier. Charge the system by means of a charging fitting in the liquid line.Weigh the refrigerant drum before charging so that an accurate record can be kept of the weightof refrigerant put in the system. If refrigerant is added to the system through the suction side ofthe compressor, charge in vapor form only.

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9. Start-Up

9.1 Compressors and condensing units will normally be delivered to the job with sufficient oil for theaverage installation. Check all compressors for proper oil level, and if necessary add sufficientoil to bring the level to the center of the crankcase sight glass. Use only the refrigeration oilrecommended by the compressor manufacturer. All oil must be delivered to the job in factorysealed, unopened containers.

9.2 Before operating any motor or other moving parts, they are to be lubricated with the proper oilor grease as necessary.

9.3 Remove or loosen shipping retainers under motor compressors. Make sure hold down nuts onspring mounted compressors are not touching the compressor feet, and are not more than 1/16”above the mounting foot.

9.4 Check high and low pressure control cut-in and cut-out points. Check water valve settings.Adjust if necessary.

9.5 After the compressor is started, continue charging until system has sufficient refrigerant forproper operation. Do not overcharge. During start-up, no compressor is to be left operatingunattended and unwatched until the system is properly charged with refrigerant and oil.

9.6 Do not add refrigeration oil while the system is short of refrigerant unless oil level is dangerouslylow. If oil has been added during charging, carefully check the compressor crankcase sight glassafter reaching a normal operating condition to be sure the system does not contain an excessiveamount of oil which can cause slugging or loss of refrigerating capacity.

9.7 The temperature controls shall be set to maintain the following temperatures in the center of thefixture before stocking:

FIXTURE TEMPERATURE °F.

(Minimum) (Maximum)Meat walk-in cooler 31 33Meat holding cooler 29 31Self-Service meat counter 31 33Dairy walk-in cooler 36 38Self-Service dairy case 36 38Produce walk-in cooler 38 40Self-Service produce counter 38 40Self-Service beverage case 38 40Frozen food storage cooler -15 -10Self-Service frozen food case -5 0Self-Service ice cream case -15 -10Meat preparation room 54 56

10. Operation and Check-Out

10.1 The Contractor shall be responsible for the proper adjustment of all controls in the system,including the controls on each refrigeration circuit, air temperature controls in the machine room,remote condenser or water tower controls, water regulating valves, or such other controls as maybe required.

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10.2 The Contractor shall check the compressor overload protectors with the manufacturer’sspecifications, and inform the Owner if they are incorrect.

10.3 The Contractor shall furnish a competent refrigeration service mechanic to check and make anynecessary adjustments to the controls during the time the fixtures are being stocked. Themechanic shall remain at the store for at least 8 hours during the first day the store is open forbusiness beginning 1 hour before opening time.

11. Identification and User Instruction

11.1 Each refrigerated fixture and cooler coil should be numbered starting at No. 1. These numbersshall be not less than 1” in height and shall be stenciled or marked neatly on the fixture in aninconspicuous location easily available to the serviceman. The compressors or condensing unitsserving the fixtures should be marked with the numbers of the cases and coils served with figuresnot less than 1 ½” in height.

11.2 All switches, starters, and controls shall be identified as to the fixture or condensing unit theyserve.

11.3 The Contractor shall turn over to the Owner one copy of all manufacturer’s literature furnishedwith each piece of equipment. Within 30 days after the store is opened, the Contractor shallinstruct the store management on the proper operation, care and upkeep of all equipment.

11.4 A permanent data sheet shall be prepared on each installation with two copies for the Owner andthe original for the installing Contractor’s files. The data sheet shall contain a complete recordof sizes and identification of all components used in the installation together with any pertinentinformation. The data sheet should include but is not limited to the following:

A. Compressor manufacturer, model, and serial number.B. Fixture manufacturer, model, and serial number.C. Design operating temperatures.D. Condensing unit model, and serial number. (If package condensing unit)E. If remote condenser, type, manufacturer, model, fan data.F. Refrigerant and weight of charge.G. Electrical service, volts, phase, cycles, wire size.H. Control circuit, voltage, fuse size.I. Contactor or starter, manufacturer, model, size, part number.J. Compressor motor protection, type, size, part number.K. Data on capacitors, relays, or other electrical components.L. Pressure control, type, size, model number, setting.M. Oil pressure safety control, type, model number.N. Defrost control, type, manufacturer, model number, setting.O. Data on miscellaneous refrigeration system components such as pressure controls, winterizing

controls, oil separators, crankcase heaters, solenoid valves, valves, etc.P. Liquid line drier, manufacturer, size, model number, connections.Q. Schematic diagram of refrigerant piping.

12. Warranty and Guarantees

12.1 All equipment and material supplied and installed by the Contractor shall be guaranteed for oneyear from the date of the store opening. The Contractor shall provide the necessary labor,

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materials, and incidental expenses to maintain the equipment in proper operation for a period ofone year from the date the store opens for business, without additional cost to the owner.(Temperature rises caused by improper stocking or abnormal air currents shall not be theresponsibility of the Contractor). The service shall not include repairs or replacements due todamage by fire, earthquake, tornado, the elements or act of God, or damage caused by misuseof the system by the Owner, power failures, broken glass, or lightning.

12.2 Official acceptance of the completed job shall be when the job is complete in every detail and hasbeen run under load conditions with satisfactory performance for a period of at least one week.

12.3 In the event any equipment furnished by the Owner is found to be defective, the Owner willcompensate the Contractor for the labor and material used in replacing the equipment orrepairing the defects.

12.4 The first year service shall include at least three complete lubrications at approximately 4 monthintervals. At the time the equipment is lubricated, each system shall be checked for properadjustment, and any necessary repairs or corrections shall be made.

12.5 Approximately 30 days prior to the expiration of the one year warranty period, the Contractor shallmake a final inspection, checking each system for proper adjustment, and correcting anydeficiencies, and shall write the Owner a letter certifying that each system is free of leaks andis operating at the specified temperature.

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SECTION 25SERVICING COPELAND COMPRESSORS

Copeland manufacturers both welded(Copelaweld) and accessible hermetic(Copelametic) motor-compressors. Welded com-pressors cannot be repaired internally in the field,and service operations on these compressors arelimited to external electrical components and nor-mal system repairs.

Copelametic motor-compressors are specificallydesigned for field accessibility if required. Remov-able heads, stator covers, bottom plates and hous-ing covers allow access for easy field repairs in theevent of compressor damage.

The description of service operations that followsis general in nature, but those sections dealingwith internal maintenance apply only to Copelameticcompressors.

COPELAND NAMEPLATE IDENTIFICATION

The model number designation on Copeland com-pressors and condensing units provides a basicidentification of the electrical and physical charac-teristics. The model numbering system forCopelametic compressors is shown in Figure 114,for Copelaweld compressors in Figure 115, and forcondensing units in Figure 116.

For example, model number 4RH1-2500-TMK-105 identifies a Copelametic motor-compressoras follows:

4 Identifies compressor familyR Identifies refrigerant cooledH Identifies 3020 CFH displacement1 Identifies basic physical characteristics2500 Identifies nominal 25 HPT Identifies three phaseM Identifies Thermotector motor protectionK Identifies 208/220/440/3/60 motor winding105 Identifies specific bill of material

identifying valves or other optional fea-tures

The serial number provides both an identificationnumber and a record of the date of manufacture.It is comprised of 8 digits. The first two identify the

year of manufacture. The third digit is a code letteridentifying the month of manufacture, the twelvemonths of the year being denoted by the firsttwelve letters of the alphabet (A for January, B forFebruary, etc.). The last five digits are assigned innumerical order during each month’s production.

The manufacturer of the motor used in the motor-compressor is also shown by a code letter preced-ing the serial number. Code letters are as follows:

C CenturyD DelcoE EmersonG General ElectricS A. O. SmithW Wagner

To illustrate, a typical serial number might be C69G19417. This would indicate:

C Century Motor69G Manufactured in July, 196919417 Identification number

The motor electrical characteristics are alsostamped on the nameplate. The motor may beoperated at voltages plus or minus 10% of thenameplate rating.

Most Copeland motor-compressors have a basicnameplate rating for both locked rotor and full loadamperes based on motor test data. The designa-tion full load amperage persists because of longindustry precedent, but in reality a much betterterm is nameplate amperage. On all Copelaweldcompressors, all new motors now being devel-oped for Copelametic compressors, and on mostof the motors developed with inherent protectionor internal thermostats, nameplate amperage hasbeen arbitrarily established as 80% of the currentdrawn when the motor protector trips. The 80%figure is derived from standard industry practice ofmany years’ standing in sizing motor protectivedevices at 125% of the current drawn at normalload conditions.

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In order for the motor to meet Copeland’s stan-dards, the trip point must be beyond the prescribedoperating limits of the compressor, and is deter-mined during qualification tests by operating thecompressor at established maximum load condi-tions and lowering the supply voltage unit the trippoint is reached. Use of the standard 80% factorenables the service and installation engineer tosafely size wiring, contactors, or other external lineprotective devices at 125% of the nameplate rat-ing, since the motor-compressor protector will notallow the amperage to exceed this figure.

In most instances, the motor-compressor is ca-pable of performing at nominal rating conditions atless than rated nameplate amperage. Because ofstandardization, one motor frequently is used invarious compressor models for air-cooled, suc-tion-cooled, water-cooled, high temperature, me-dium temperature, low temperature, R-12, R-22,or R-502 applications as required. Obviously onmany applications there will be a greater safetyfactory than on others.

When Copeland motor-compressors are listedwith U. L., the basic compressor nameplate ratingis listed as a maximum. This allows O.E.M. usersto list a lower unit nameplate rating should the unitelectrical load be less than the original compressorrating. Frequently this permits the use of smallerfuses and wire sizes.

In order to avoid any conflict in the nameplateratings of the compressor and the unit in smallpackaged equipment, some Copelaweld compres-sors now have no full load rating stamped on thenameplate, and are assigned an “80% of tripamps” rating on specification sheets. AllCopelaweld compressors carry a locked rotor rat-ing on the nameplate, and all Copelametic com-pressors have both a locked rotor and a full loadamperage rating on the nameplate.

IDENTIFICATION OF PORT LOCATIONS INHEADS OF COPELAMETIC MOTOR-COMPRESSORS

In addition to the service ports normally availableon suction and discharge compressor servicevalves, on Copelametic compressors high and lowpressure ports are provided in the compressor

head. These provide a convenient connection forhigh and low pressure controls, and unlike theports in service valves, cannot be accidentallyclosed off.

The port locations in various compressor modelsare shown in Figure 117.

IDENTIFICATION OF MOTOR TERMINALS ONSINGLE PHASE COMPRESSORS

The terminal plates on Copelametic compressorsare stamped with the terminal identification, andidentifying the common, run, and start terminals isseldom a problem. This is also true where teeblocks are used on Copelaweld compressors, butmany Copelaweld compressors are manufacturedwith a Fusite terminal which may have no perma-nent identification.

Fig. 118 shows the various motor terminal configu-rations used by Copeland.

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Type A illustrates the individual terminal postsused on smaller horsepower Copelametic com-pressors. Type A follows no standard industrypattern and applies only to Copelametic compres-sors. The terminals are in the order shown whenviewed from the stator cover end of the compres-sor (the end on which the terminal box is mounted).

Type B is a tee block used on larger horsepowercompressors, both Copelametic and Copelaweld.Type C is a Fusite connection, normally used withpush-on type terminals.

Both Type B and Type C for production conve-nience and easy identification, follow the generalindustry rule of identifying common, start, and runterminals, always in that order, in the same fashionas reading a book. In other words, reading fromleft to right, and from top to bottom, the terminalsare always C, S, and R.

PROPER VALVE PLATE AND HEAD GASKETSFOR 3, 4, AND 6 CYLINDER COMPRESSORS

Occasionally when quick delivery of either new orreplacement motor-compressors is required froma wholesaler’s stock, and the exact model is not onhand, compressor heads may be changed in thefield in order to utilize available stock compres-sors.

WARNINGWhen compressor heads are changed to con-vert standard, capacity control, or two-stagecompressors to some other model, the correctgaskets must be used to insure proper perfor-mance and prevent damage to the compres-sor. The correct head gasket must exactlymatch the inner face of the head being used.

Standard Compressor Heads

Figure 119 is an inside view of a typical standardCopelametic compressor head, showing the innerwebbing. The discharge port is located in the valveplate in the area indicated, and the proper gasketmatches the inner face of the head.

External Capacity Control Heads

Figure 120 is an inside view of a Copelametic headequipped with an external unloading valve. Thevalve is mounted on a discharge port located in thetop of the head. The normal discharge port areais fenced off by the “Y” in the inner webbing. Theproper gasket exactly matches the inner face of

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the head, the gasket for the external unloadinghead being externally identified by the tab shownin Figure 120.

Since the area enclosed by the “Y” in the webbingis exposed to discharge pressure from the othercylinders, any leakage from the discharge port inthe valve plate into the discharge chamber of anunloaded head can flow directly back to the suctionchamber. Such leakage can cause the compres-sor suction pressure to rise immediately when thecompressor is pumped down if the unloader valveis not tightly seated.

When a standard heat is replaced with a headequipped with an external unloading valve, thegasket must be changed and the correct gasket

must be installed to prevent overheating of thecompressor.

In the event unloading is not desired on a cylin-der bank equipped with a head designed forunloading, both the cylinder head and gasketmust be replaced. The correct gasket must beinstalled to prevent damage to the compressor.

A new internal type unloader is currently underdevelopment which will also require a specialhead, but the inner face of the head will be thesame as a standard head, and the standard gasketmay be used for the unloaded head as well.

Two Stage Heads, 3 Cylinder

On two stage compressors, special heads arenecessary to provide the necessary separation ofthe two stages of compression. Figure 121 is aninside view of a typical Copelametic head for a 3cylinder two stage compressor.

Refrigerant vapor is returned directly from thesuction line to the port in the cylinder head openinginto the low stage suction chamber, and is thendischarged by the low stage cylinders into the lowstage discharge chamber. The gas (at interstagepressure) then enters the interstage manifold, isdesuperheated by liquid refrigerant fed by thedesuperheating expansion valve, and is dischargedinto the compressor motor chamber. The highstage suction gas follows the normal suction gasflow path from the motor chamber to the high stagesuction chamber, and is then discharged to thecondenser through the high stage discharge cham-ber.

The proper gasket exactly matches the inner web-bing of the head, and must be used to preventleakage between stages and possible overheatingof the compressor motor.

Two Stage Heads, 6 Cylinder Compressor

On 6 cylinder two stage compressors, differentheads must be used on the high and low stagecylinders. When viewed from the bearing housingend of the compressor (the end on which the oilpump is mounted) the center and right cylinderbanks are low stage, and the left cylinder bank is

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high stage.

banks

Figure 123 is an inside view of a typical low stagehead for a 6 cylinder compressor, while Figure 124shows an inside view of a typical high stage head.

Refrigerant vapor is returned from the suction lineto the normal discharge chamber on the compres-sor. The vapor enters the low stage suctionchamber through the port at the end of the valveplate, and is discharged from the low stage cylin-ders into the low stage discharge chamber. Thegas (at interstage pressure) then enters theinterstage manifold, is desuperheated by liquidrefrigerant fed by the desuperheating expansionvalve, and is discharged into the compressor mo-tor chamber.

The low stage head is made with the area over thenormal suction port blocked off. The proper gas-ket exactly matches the inner face of the head withthe exception that the gasket outlines the solidarea, but does not cover it completely.

The high stage head on two stage 6 cylindercompressors is similar to the head used on an

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unloaded head on 6 cylinder compressors, andtakes the same head gasket. The high stagesuction gas follows the normal suction gas flowpath from the motor chamber to the high stagesuction chamber, and is then discharged to thecondenser through the high stage discharge cham-ber.

Identification of Head Gaskets

As a means of easily identifying head gaskets, andas a guide to proper installation, tabs have beenprovided on gaskets used on capacity control andtwo stage heads on 3, 4, and 6 cylinder compres-sors. In the even there is a question as to whetherthe proper gasket has been installed, the externaltab provides a convenient means of checkingwithout having to remove the compressor head.

Standard head gaskets have no tab, and follow theconfiguration of the head. The position of the tabwhen the gasket is properly installed on external

capacity control and two stage compressors isillustrated in Figures 125, 126, 127, and 128.

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Any time a compressor head is changed, theproper gaskets must be used to prevent dam-age to the compressor. Compressor failuresor compressor damage due to use of impropergaskets will be considered as misuse not cov-ered by the Copeland warranty, and regularreplacement charges will apply.

COPELAND OIL PUMPS

On all Copelametic compressors 5 HP and largerin size, and on 3 HP “NR” models, compressorlubrication is provided by means of a positivedisplacement oil pump. The pump is mounted onthe bearing housing, and is driven from a slot in thecrankshaft into which the flat end of the oil pumpdrive shaft is fitted.

Oil is forced through a hole in the crankshaft to thecompressor bearings and connecting rods. A springloaded ball check valve serves as a pressure reliefdevice, allowing oil to bypass directly to the com-pressor crankcase if the oil pressure rises aboveits setting.

Since the oil pump intake is connected directly tothe compressor crankcase, the oil pump inletpressure will always be crankcase pressure, andthe oil pump outlet pressure will be the sum ofcrankcase pressure plus oil pump pressure. There-fore, the net oil pump pressure is always the pumpoutlet pressure minus the crankcase pressure.When the compressor is operating with the suctionpressure in a vacuum, the crankcase pressure isnegative and must be added to the pump outletpressure to determine the net oil pump pressure.A typical compound gauge is calibrated in inchesof mercury for vacuum readings, and 2 inches ofmercury are approximately equal to 1 psi.

For example:Pump Net OilOutlet Pump

Crankcase Pressure Pressure Pressure50 psig 90 psig 40 psi8” vacuum 36 psig 40 psi(equivalent to areading of minus 4 psig)

In normal operation, the net oil pressure will varydepending on the size of the compressor, the

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temperature and viscosity of the oil, and the amountof clearance in the compressor bearings. Net oilpressures of 30 to 40 psi are normal, but adequatelubrication will be maintained at pressures down to10 psi. The bypass valve is set at the factory toprevent the net pump pressure from exceeding 60psi.

Every oil pump is given a 100% operating inspec-tion at the Copeland factory prior to shipment. Thepump is installed in a test stand and must lift oilthrough unprimed oil lines to a height not less than12 inches, pick up and develop a full flow of oilwithin 30 seconds, must not exceed an estab-lished maximum power requirement, must de-velop a minimum of 40 psi pressure with the mainoutlet closed, and must pump a specified quantityof oil at standard test conditions. Operating pres-sures and reversal of the pump are checked on thetest stand, and on larger compressors are checkedagain after the pump is installed in a compressor.

The oil pump may be operated in either direction,the reversing action being accomplished by afriction plate which shifts the inlet and outlet ports.After prolonged operation in one direction, wear,corrosion, varnish formation, or burrs may developon the reversing plate, and this can prevent thepump from reversing. Therefore, on installationswhere compressors have been in service for sometime, care must be taken to maintain the originalphasing of the motor if for any reason the electricalconnections are disturbed. On transport refrigera-tion applications where power may be providedfrom both generators and dock power, both sourcesof power must be phased alike when connected tothe unit in order to prevent reversing the compres-sor rotation.

The presence of liquid refrigerant in the crankcasecan materially affect the operation of the oil pump.Violent foaming on start up can result in a loss ofoil from the crankcase, and a resulting loss of oilpressure until oil returns to the crankcase. If liquidrefrigerant or a refrigerant rich mixture of oil andrefrigerant is drawn into the oil pump, the resultingflash gas may result in large variations and possi-bly a loss of oil pressure. Crankcase pressure mayvary from suction pressure since liquid refrigerantin the crankcase can pressurize the crankcase forshort intervals, and the oil pressure safety control

low pressure connection should always be con-nected to the crankcase.

During a rapid pull-down of the refrigerant evapo-rating pressure, the amount of refrigerant in solu-tion in the crankcase oil will be reduced, and maycause flash gas at the oil pump. During this periodthe oil pump must pump both the flash gas and oil,and as a result the oil pressure may decreasetemporarily. This will merely cause the oil pump tobypass less oil, and so long as the oil pressureremains above 9 psi, adequate lubrication will bemaintained. As soon as a stabilized condition isreached, and liquid refrigerant is no longer reach-ing the pump, the oil pressure will return to normal.

The oil pressure safety control high pressure con-nection should be made to the oil pressure port onthe oil pump as shown. On the initial start-up of asystem, or if at anytime abnormal noise causesany question regarding lubrication, it is recom-mended that a gauge be attached to the Schradertype valve so that the oil pressure can be observedwhile the compressor is in operation. The Schradertype valve is for pressure checking only, and isnormally closed, so the oil pressure safety controlmust never be connected to this port.

The oil pump face plate is held in place by the twobolts shown in Figure 129. (Note that these are

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smaller than the six mounting bolts). The faceplate seats on an “O” ring seal and should not beremoved. Do not put a gasket between the faceplate and the oil pump body, or the oil pump will berendered inoperative.

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The bolt holding the spring loaded bypass assem-bly in place should not be removed. The bypasspressure is not adjustable, and the bolt is providedfor access during original assembly or factorymaintenance, but it is not intended for field repairs.If the bolt is removed, the spring or other compo-nents are easily lost or damaged, rendering the oilpump inoperative.

Copeland oil pumps are identified with a letterstamped into the casting as shown in Figure 129and 130 and all are identical except for the pilotdiameter.

Oil pumps identified with an “L” have a 1-15/16”O.D. pilot diameter, are designed for use on all 4Rand 6R compressors, and will not fit any othercompressor.

“S” oil pumps have a 1 ½” O.D. pilot diameter, andwere standard on all two and three cylinder com-pressors having oil pumps for many years. The “S”model oil pump is being replaced in current pro-duction with the “A” model oil pump, because of achange in bearing design on N, M, and 9 modelcompressors.

The “A” model oil pump has a 1 1/8” O.D. pilotdiameter. It differs from the “S” and “L” oil pumpsin that it is designed to register in the bearing ratherthan the bearing housing. This makes possible anew style line bored oil pump housing bearingproviding accurate alignment of the oil pump.

A larger capacity oil pump with a double impellerhas been developed for larger displacement com-pressors, but it is interchangeable with standard oilpumps with the exception that longer mountingbolts are required.

Field Replacement of Oil Pumps

If it is determined that an oil pump is not functioningproperly, replace the oil pump and not the com-pressor.

The oil pump is mounted on the compressorbearing housing by means of the six bolts shownin Figure 129. Compressor bearing housings arenot interchangeable on most compressor bodiesand should not be removed.

Gaskets installed between the oil pump and thecompressor body are shown in Figure 132. Thetab on the gasket has been added solely for aid inidentification and alignment. The gasket must beinstalled with the tab in the position shown (11o’clock position) when viewed facing the compres-sor, and the slotted hole must always be to theinstaller’s left in the 9 o’clock position. If the gasketis installed in any other position, the oil ports will beblocked. Gaskets for “L” oil pumps are not inter-changeable with gaskets for “A” and “S” pumps.

Some older models of Copelametic compressorsare equipped with Tuthill oil pumps, and these maybe furnished on service replacement compres-sors. The Copeland oil pump is perfectly inter-changeable with the Tuthill pump, and the samegaskets may be used.

WARNINGThe oil pump pilot shoulder must registersnugly in either the bearing housing or bearing(depending on compressor design) to insurecentering the oil pump. See Figure 131. If notproperly registered, the resulting misalign-ment can result in excessive wear and pos-sible failure of the oil pump. Tolerances arevery critical for proper operation and extremecare must be taken to insure that proper oilpump, and adaptor if required, is used. Thefollowing replacement procedures must befollowed to insure trouble free operation.

1. Replacement of “L” oil pumps (4R and 6Rcompressors.)Use only “L” oil pumps. Occasionally a service-man will mount an “A” oil pump on a 4R or 6Rcompressor by mistake, and since the pilotshoulder will not register on the bearing hous-ing, excessive play and misalignment of theshafts will develop resulting in failure of the oilpump. The pump should register in the bearinghousing.

2. Replacement of “S” oil pumps with “A” replace-ment kit (M, N, 9 model compressors). Adap-tors have been developed for the “A” oil pumpso it can be used as a replacement on a l ltwo and three cylinder Copelametic compres-sors having oil pumps, regardless of the com-pressor pilot diameter. The “A” replacement kit

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can be used to replace “S” oil pumps ona l lolder model M, N, and 9 compressors whichhave bearing housing pilot diameters, by usingthe 1 ½” O.D. adaptor.

3. Replacement of “A” oil pump on NRL, NRM,NRN, 9R, 9T, 9W model compressors. Theabove compressor models with “A” oil pumpshave an extended bearing, with a 1 ¼” I.D.nominal register. The “A” replacement kit canbe used to replace the original “A” pump byusing the 1 ¼” O.D. adaptor.

4. Replacement of “A” oil pump on MR, MW,NRA, NRB, NRD, NRE model compressors.The above compressor models with “A” oilpumps have an extended bearing with a 1 1/8”nominal I.D. register. The “A” replacement kitcan be used to replace the original “A” pumpwithout the use of any adaptor.

TYPICAL COPELAMETIC COMPRESSORCONSTRUCTION

The following exploded views illustrate typicalCopeland compressor construction details. Indi-vidual components will vary with different com-pressor models, but the basic method of assemblyis similar.

MAINTENANCE ACCESSIBILITY ONCOPELAMETIC COMPRESSORS

The heads may be removed on all Copelameticcompressors by removing the head bolts as shownin Figure 139.

The valve plate is then accessible and may beremoved as shown in Figure 140. Note that thesuction valve reeds are retained in position bydowel pins in the body.

If the motor-compressor is not seized internally itis normally possible to move the pistons by exert-ing force on the top of the piston, as illustrated inFigure 141. In the event of a broken connectingrod, the piston may “float” in the cylinder duringoperation. The connecting rod is broken if thepiston can be depressed with little or no pressurewithout affecting the position of the other piston orpistons.

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Figure

142 shows the location of the suction strainerscreen on small Copelametic compressors. If arestriction somewhere in the low pressure side ofthe system is indicated, it is advisable to check thestrainer for restriction.

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The compressor motor terminals and externalprotectors are accessible by removing the terminalbox lid as shown in Figure 143. The terminal boxcan be removed by removing the attaching screws.

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Figure 144 is a view of the motor end of a smallcompressor with the stator cover removed. Notethat the external protector, on top of the body isheld in position so that it has perfect contact withthe compressor body when in the proper position.

This particular model uses an oil flinger for lubrica-tion. The ends of the oil flinger run through the oil,some of which is picked up by the “V” near the endsof the arms. The flinger deposits the oil at the topof the stator cover, which then drains into the oilwell shown on the stator cover in Figure 145. Notethat the oil tube which centers in the hollow crank-shaft then permits oil to run from the well throughthe crankshaft to provide lubrication to the movingparts.

Figure 146 shows arrows on the motor housingcover which must point upward in order that the oilwell will be in a proper position to trap the oil.

FIELD TROUBLESHOOTING

One of the basic difficulties in preventing compres-sor failures arises in determining the actual reasonfor the failure. The compressor is the functioningheart of the refrigeration system, and regardless ofthe nature of a system malfunction, the compres-sor must ultimately suffer the consequences. Sincethe compressor is the component that fails, thereoften is a tendency to blame any failure on thecompressor without determining the actual causeof the malfunction. In far too many cases, theactual cause of failure has not been discoveredand corrected and the result has been recurringfailures that could have been prevented.

If the service engineer is to help in eliminating thecauses of compressor failure, then he must thor-oughly understand both the operation of the sys-tem and the possible causes of failure that mightoccur, and he must be on the alert for any signs ofsystem malfunction.

If a motor compressor fails to start and run prop-erly, it is important that the compressor be testedto determine its condition. It is possible thatexternal electrical components may be defective,the protector may be open, a safety device may betripped, or other conditions may be preventingcompressor operation. If the motor compressor is

not the source of the malfunction, replacing thecompressor will only result in the unnecessaryexpenditure of time and money, while the basicproblem remains.

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If the service engineer closes his eyes to a basicsystem malfunction, or an improper control set-ting, or an operating condition he knows is notright, he is not fooling the system or the compres-sor; he is only fooling himself.

Every service man should have this motto embla-zoned in his mind “Do the job right the first time.”If you can’t find time to do it right, how can you findtime to do it over again?

Schematic Wiring Diagram, Single PhaseMotors

Actual field wiring diagrams may vary considerablyin style or format, but Figure 147 is a simpleschematic illustration of the basic wiring connec-tions and compressor motor winding relationshipsin a single phase motor. The diagram as shownillustrates a capacitor start, capacitor run motor,but the same diagram can apply to a permanentsplit capacitor motor if the starting capacitors andrelay are removed, and can apply to a capacitorstart, induction run motor if the running capacitoris removed.

A thorough understanding of the basic wiringconnections is essential to successfully diagnosefield electrical problems on single phase compres-sors.

If the Compressor Will Not Run

1. If there is no voltage at the compressor termi-nals, follow the wiring diagram (Figure 148)and check back from the compressor to thepower supply to find where the circuit is inter-rupted.

Check the controls to see if the contact pointsare closed (low pressure control, high pres-sure control, thermostat, oil pressure safetycontrol, etc.). If a contactor is used check tosee if the contacts are closed. Check for ablown fuse, open disconnect switch, or looseconnection.

2. If power is available at the compressor termi-nals, and the compressor does not run, checkthe voltage at the compressor terminals whileattempting to start the compressor (see Figure149).

If the voltage at the compressor terminals isbelow 90% of the nameplate voltage, it ispossible the motor may not develop sufficienttorque to start. Check to determine if wiresizes are adequate, electrical connections areloose, the circuit is overloaded, or if the powersupply is adequate.

3. On units with single phase PSC motors, thesuction and discharge pressures must be equal-ized before starting because of the low startingtorque of the motor. Any change in the refrig-erant metering device, the addition of a drier,or other changes in the system componentsmay delay pressure equalization and createstarting difficulties. If PSC motor starting prob-lems are being encountered, the addition of acapacitor start kit is recommended.

4. On single phase compressors, a defectivecapacitor or relay may prevent the compressorstarting. If the compressor attempts to start,but is unable to do so, or if there is a hummingsound, check the relay to see if the relaycontacts are damaged or fused. The relaypoints should be closed during the initial start-ing cycle, but should open as the compressorcomes up to speed.

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Remove the wires from the starting relay andcapacitors. Use a high voltage ohmmeter tocheck for continuity through the relay coil.Replace the relay if there is no continuity. Usean ohmmeter to check across the relay con-tacts. Potential relay contacts are normallyclosed when the relay is not energized, currentrelay contacts are normally open. If eithergives an incorrect reading, replace the relay.

Any capacitor found to be bulging, leaking, ordamaged should be replaced.

Make sure capacitors are discharged beforechecking. Check for continuity between eachcapacitor terminal and the case. Continuityindicates a short, and the capacitor should bereplaced.

Substitute “a known to be good” start capacitorif available. If compressor then starts and runsproperly, replace the original start capacitor.On PSC motors, substitute “a known to begood” run capacitor if available. If compressorthen starts and runs properly, replace theoriginal run capacitor.

If a capacitor tester is not available, an ohm-meter may be used to check run and startcapacitors for shorts or open circuits. Use anohmmeter set to its highest resistance scale,and connect prods to capacitor terminals.

(a) With a good capacitor, the indicator shouldfirst move to zero, and then gradually in-crease to infinity.

(b) If there is no movement of the ohmmeterindicator, an open circuit is indicated.

(c) If the ohmmeter indicator moves to zero,and remains there or on a low resistancereading, a short circuit is indicated. Defec-tive capacitors should be replaced.

5. If the correct voltage is available at the com-pressor terminals, and no current is drawn,remove all wires from the terminals and checkfor continuity through the motor windings. Onsingle phase motor compressors, check forcontinuity from terminals C to R, and C to S. On

three phase compressors, check for continuitybetween the terminals for connections tophases 1 and 2, 2 and 3, and 1 and 3. Oncompressors with line break inherent protec-tors, an open overload protector can cause alack of continuity. If the compressor is warm,wait one hour for compressor to cool and re-check. If continuity cannot be establishedthrough all motor windings, the compressorshould be replaced.

Check the motor for ground by means of acontinuity check between the common termi-nal and the compressor shell. If there is aground, replace the compressor.

6. If the compressor has an external protector,check for continuity through the protector orprotectors. (See Figure 150)

All external and internal inherent protectors onCopelametic compressors can be replaced inthe field. On larger compressors with thermo-stats, thermotectors, or solid state sensors, inthe motor windings (D, H, M, S protection), the

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internal protective devices cannot be replacedand the stator or compressor must be changedif the internal protectors are defective or dam-aged.

If The Motor Compressor Starts But Trips Re-peatedly On The Overload Protector

1. Check the compressor suction and dischargepressures while the compressor is operating.(See Figure 151.) Be sure the pressures arewithin the limitations of the compressor. Ifpressures are excessive, it may be necessaryto clean the condenser, purge air from thesystem, add a crankcase pressure regulatingvalve, modify the system control, or take suchother action as may be necessary to avoidexcessive pressures.

An excessively low suction pressure may indi-cate a loss of charge, and a suction cooledmotor compressor may not be getting enoughrefrigerant vapor across the motor for propercooling.

On units with no service gauge ports wherepressures can be checked, check condenserto be sure it is clean and fan is running.Excessive temperatures on suction and dis-charge line may also indicate abnormal oper-ating conditions.

2. Check the line voltage at the motor terminalswhile the compressor is operating. (See Fig-ure 149.) The voltage should be within 10% ofthe nameplate voltage rating. If outside thoselimits, the voltage supply must be broughtwithin the proper range, or a motor compres-sor with different electrical characteristics mustbe used.

3. Check the amperage drawn while the com-pressor is operating. (See Figure 152.) Undernormal operating conditions, the amperagedrawn will seldom exceed 110% of the name-plate amperage and should never exceed 120%of the nameplate amperage. High amperagecan be caused by low voltage, high head pres-sure, high suction pressure, low oil level, com-pressor mechanical damage, defective run-ning capacitors, or a defective starting relay.

On three phase compressors, check amper-age in each line. One or two high amperagelegs on a three phase motor indicates anunbalanced voltage supply, or a winding imbal-ance. If all three legs are not drawing approxi-mately equal amperage, temporarily switchthe leads to the motor to determine if the highleg stays with the line or stays with the terminal.If the high amperage reading stays with theline, the problem is in the line voltage supply.If the high amperage reading stays with theterminal, the problem is in the motor.

If the amperage is sufficiently unbalanced tocause a protector trip, and the voltage supplyis unbalanced, check with the power companyto see if the condition can be corrected. If the

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voltage supply is balanced, indicating a defec-tive motor phase, the compressor should bereplaced.

4. Check for a defective running capacitor orstarting relay in the same manner described inthe previous section.

5. Check the wiring against the wiring diagram inthe terminal box. On dual voltage motors,check the location of the terminal jumper barsto be sure phases are properly connected.(See Figure 153.)

6. Overheating of the cylinders and head can becaused by a leaking valve plate. To check,close the suction service valve and pump thecompressor into a vacuum. Stop the compres-sor and crack the suction valve to allow thepressure on the suction gauge to build up to 0psig. Again close the valve. If the pressure onthe gauge continues to increase steadily, thevalve plate is leaking. Remove the head andcheck the valve plate, replace if necessary.(See Figure 154.)

7. If all operating conditions are normal, the volt-age supply at the compressor terminals bal-anced and within limits, the compressor crank-case temperature within normal limits, and theamperage drawn within the specified range,the motor protector may be defective, andshould be replaced.

If the operating conditions are normal and thecompressor is running excessively hot for noobservable reason, or if the amperage drawnis above the normal range and sufficient torepeatedly trip the protector, the compressorhas internal damage and should be replaced.

If The Compressor Runs But Will NotRefrigerate

1. Check the refrigerant charge. If sight glass isavailable, it should show clear liquid. Checkthe evaporator surface to determine if it isevenly cold throughout, or if partially starved.A lack of charge may be indicated by light,fluffy frost at the expansion valve and evapora-tor inlet. Add refrigerant if necessary.

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2. Check the compressor suction pressure. Anabnormally low pressure may indicate a loss ofrefrigerant charge, a malfunctioning expan-sion valve or capillary tube, a lack of evapora-tor capacity possibly due to icing or low air flow,or a restriction in the system.

Often a restriction in a drier or strainer can beidentified by frost or a decrease in temperatureacross the restriction due to the pressure dropin the line. This will be true only if liquidrefrigerant is in the line at the restricted point,since any temperature change due to restric-tion would be caused by the flashing of liquidinto vapor as the pressure changes.

Any abnormal restrictions in the system mustbe corrected.

3. Check the compressor discharge pressure.An abnormally high discharge pressure cancause loss of capacity, and can be caused bya dirty condenser, a malfunctioning condenserfan, or air in the system.

4. If the suction pressure is high, and the evapo-rator and condenser are functioning normally,check the compressor amperage draw. Anamperage draw near or above the nameplaterating indicates normal compressor operation,and it is possible the compressor or unit mayhave damaged valves or does not have suffi-cient capacity for the application.

An amperage draw considerably below thenameplate rating may indicate a broken suc-tion reed or broken connecting rod in thecompressor. Check the pistons and valveplate on an accessible compressor. If no otherreason for lack of capacity can be found,replace a welded compressor.

Service Diagnosis Chart

Table 52 is a service diagnosis chart which canserve as a checklist of possible causes for varioussystem malfunctions. While unusual conditionsmay occasionally occur, the chart covers the com-mon types of malfunctions normally encountered.


SECTION 26FUNDAMENTALS OF SERVICE OPERATIONS

The installation and maintenance of refrigerationequipment is one of the most exacting and de-manding tasks in the service field. In addition tothe care necessary in working with equipment builtwith fine precision to the close tolerances required,refrigerants introduce an additional hazard. Ser-vicemen often tend to underestimate how muchcare is required to properly protect a system.

So long as a refrigerant is tightly imprisoned andproperly controlled, it can be made to performuseful work. But it doesn’t do it willingly. Given theslightest opportunity, it will escape. If joined bysuch common substances as moisture or air, itcombines with them to form acids and attack thesystem. And, if left uncontrolled for even a fewhours, it can migrate through the system, oftenwith fatal results to the compressor on start-up.When handling refrigerants, the serviceman cannever relax, he must always be alert and on guard.

CONTAMINANTS

Absolute cleanliness is essential in a refrigerationsystem. In order to insure a reliable, trouble freeunit, there are no compromises.

Unlike most other mechanical equipment, refrig-eration systems are vulnerable to attack from twocommon contaminants, air and water, which can-not be seen. Yet if either or both are present in asystem, they quickly join in a common attack onthe refrigerant and oil, and can cause corrosion,copper plating, acid formation, sludging, and otherharmful reactions.

Antifreeze solutions or other additives may createundesirable chemical reactions in a system. Addi-tives of any type are not recommended and shouldnot be used.

It is amazing, and sometimes almost unbelievable,to see the many foreign materials that have en-tered a refrigeration system and end up in thecompressor. Filings, shavings, dirt, solder, flux,

metal chips, bits of steel wool, mortar, sand fromsandcloth, wires from cleaning brushes, lengths ofcopper tubing—all have been encountered. Ex-amination of returned compressors indicates thatmany early failures could have been prevented ifthe contaminants had been removed from thesystem at the time of installation. This type ofproblem is encountered most often on field in-stalled systems, and it seems inescapable thatmany of the contaminants found in systems couldget there only from carelessness during installa-tion.

When brazing copper tubing and fittings, copperoxide is invariably formed on the inside of the tubeunless nitrogen or some other inert gas is circu-lated through the tubing during the brazing opera-tion. That oxide can become a powdered abra-sive, plugging oil passages, scoring bearings,plugging filters, and causing other injurious ef-fects.

Reasonable care during installation and servicecan keep contamination in a system at a safe andacceptable level.

1. Take care to keep tubing clean and dry.

2. Pass an inert gas through the tubing whenbrazing refrigerant tubes.

3. Take extreme care to keep foreign materialsout of the system when it is opened for service.

4. Suction line filters and liquid line filter-driersshould be installed in all field installed systems.

5. Thoroughly evacuate the system at the time oforiginal installation, or after exposure for longperiods, during maintenance.

6. Install a new filter-drier in the liquid line eachtime the system is opened for service.

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HANDLING OF REFRIGERANT CONTAINERS

The pressure created by liquid refrigerant in asealed storage container is equal to its saturationpressure at the liquid temperature so long as thereis vapor space available. If however, the containeris over-filled, or if in the case of gradual anduniform overheating the liquid expands until thecontainer becomes liquid full, hydrostatic pressurebuilds up rapidly to pressures far in excess ofsaturation pressures. Figure 155 illustrates thedangerous pressures that can be created undersuch circumstances, which can result in possiblerupture of the refrigerant container such as illus-trated in Figure 156.

The chart in Figure 155 illustrates the pressure-temperature relationship of liquid refrigerant be-fore and after a cylinder becomes liquid-full undergradual and uniform heating. The true pressure-temperature relationship exists up to the pointwhere expansion volume is no longer availablewithin the cylinder.

If a refrigerant cylinder becomes liquid-full, hydro-static pressure builds up rapidly with only a smallincrease in temperature. Excessive pressure build-up can cause cylinder rupture as pictured. Underuniform conditions of heating, the cylinder illus-trated ruptured at approximately 1,300 pounds persquare inch gauge pressure. If heat is applied witha torch to a local area, cylinder wall may beweakened at this point and the danger of rupturewould be increased. In a controlled test a cylindersuch as the one pictured flew over 40 ft. in the airupon rupture—a dramatic demonstration of thedanger of over-heating cylinders.

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Interstate Commerce Commission regulations pre-scribe that a liquified gas container shall not beliquid full when heated to 55°C. (131°F.). If cylin-ders are loaded in compliance with this regulation,at temperatures above 131°F. liquid refrigerantmay completely fill a container because of expan-sion of the liquid at increasing temperatures. Fus-ible metal plugs are designed to protect the cylin-der in case of fire, but will not protect the cylinderfrom gradual and uniform overheating. Fusiblemetal plugs begin to soften at 157°F., but hydro-static pressure developed at 157°F. is far in excessof cylinder test pressure.

The following safety rules should be followed at alltimes when handling cylinders of compressed gas.

1. Never heat a cylinder above 125°F.

2. Never store refrigerant cylinders in the directsunlight.

3. Never place an electric resistance heater indirect contact with a refrigerant cylinder.

4. Never apply a direct flame to a cylinder.

5. When refilling small cylinders, never exceedthe weight stamped on the refrigerant cylinder.

6. Do no drop, dent, or otherwise abuse cylin-ders.

7. Always keep the valve cap and head cap inplace when the cylinder is not in use.

8. Always open all cylinder valves slowly.

9. Secure all cylinders in an upright position to astationary object with a strap or chain whenthey are not mounted in a suitable stand.

The common fluorocarbon refrigerants (R-12, R-22, R-502) were originally developed by Dupont as“Freon” refrigerants, but different manufacturersuse different trade names for the same refrigerant.For example R-12 is the common industry desig-nation for the refrigerant Dichlorodifluoromethane,but it may be marketed as Freon 12, Genetron 12,Isotron 12, Ucon 12, etc. Refrigerant containersare usually color coded as follows:

R-11 OrangeR-12 WhiteR-22 GreenR-502 Purple

SAFE HANDLING OF COMPRESSED GASESWHEN TESTING OR CLEANING REFRIGERA-TION SYSTEMS

When the use of an inert gas is required for highpressure test purposes or to flush a contaminatedsystem, Copeland recommends the use of eitherdry nitrogen (N2) or dry carbon dioxide (CO2). At70°F., dry nitrogen in “K” cylinders may be undera pressure of 2200 psig or more, and carbondioxide at the same temperature may be under apressure in excess of 830 psig. Extreme cautionmust be exercised in the use of highly compressedgases, since careless or improper handling can bevery dangerous.

Oxygen or acetylene should never be used forpressure testing or cleanout of refrigeration sys-tems, as the use of either may result in a violentexplosion. Free oxygen will explode on contactwith oil, and acetylene will explode spontaneouslywhen put under pressure unless dissolved in aspecial holding agent such as used in acetylenetanks.

WARNING - HIGH PRESSURE COMPRESSEDGASES SHOULD NEVER BE USED IN REFRIG-ERATION SYSTEMS WITHOUT A RELIABLEPRESSURE REGULATOR AND PRESSURERELIEF VALVE IN THE LINES AS DESCRIBEDHEREIN.

Recommended Test Pressures

All new Copelametic and Copelaweld compres-sors are now designed with a crankcase ultimatebursting pressure in excess of 850 psig, andproduction samples are periodically checked hy-drostatically to insure this standard being main-tained. Many older models of Copeland compres-sors and all belt driven compressor crankcaseswere designed for a minimum of 650 psig burstingpressure. However, the ultimate burst test is astrength test only, and both leaks and distortion

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can occur at high pressures even though thecrankcase may not rupture.

Every Copelametic compressor crankcase is sub-jected to a 300 psig pressure at the factory, andevery Copeland compressor is leak tested at aminimum of 175 psig.

Because of the possibility of damage in transit, andthe hazard of rupture with compressed gas or air,plus the fact that many manufacturers do notdesign for crankcase pressures as high asCopeland, it is recommended that all crankcasetest pressures and all leak test pressures belimited to a maximum of 175 psig. U. L. safetystandard for condensing units normally can be metby testing the complete unit at the required lowside pressure of 150 psig.

In the event high side test pressures are required,the crankcase must be protected from the highpressure, not only as a safety measure, but also toprevent possible distortion of the crankcase result-ing in noise or mounting problems.

High side pressure conditions are dictated by theintended usage. Copeland minimum high side testpressures for unit applications are as follows, butthe maximum is not to exceed 500 psig.

Copeland Unit High Side MinimumApplication Leak TestPressureR-12, Air or Water Cooled 335 psigR-22 and R-502, Water Cooled 335 psigR-22 and R-502, Air Cooled 450 psig

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Figure 157 illustrates what can happen to a compressor if exposed to pressures in excess of the compressor’sultimate strength. This type of damage most frequently occurs when servicemen attempt to purge or pressurize arefrigeration system with high pressure compressed gases without a pressure regulator.


Recommended Procedure for Leak orPressure Tests

Figure 158 illustrates the gauges and valves thatmust be installed in the supply line for propersafety of personnel and equipment when testingwith high pressure gases.

1. Separate relief valves for high and low sidetests are required, one preset for 175 psig forlow side tests, including the crankcase; theother preset at the required high side pressure.

2. When testing at pressures above 175 psig, thecompressor and low pressure componentsmust be disconnected from the system. Shouldit be impractical to disconnect the compressorduring high side pressure test, an adequatemeans of pressure relief must be provided onthe compressor crankcase to prevent damagein the event the high pressure gas should leakback into the crankcase. A bleed line, ifprovided, should be larger than the line fromthe gas cylinder.

3. With the compressed gas cylinder in the up-right position, admit the dry nitrogen or drycarbon dioxide slowly until the desired systempressure is obtained.

4. Close the cylinder valve. Check the systempressure gauge, and adjust as necessary toobtain the proper pressure.

5. Proceed with test, and when complete, systempressure should be reduced to 0 psig, com-pressor reconnected, the system evacuated,

and then charged with the proper kind andamount of refrigerant.

Recommended Procedure For Purging Con-taminated Systems

Evacuation is the only dependable and effectivemeans of removing air and moisture from a systemto the required low level. If air is trapped in thecompressor, it is practically impossible to removefrom the compressor crankcase by purging. Incase of a motor burn, Copeland recommends onlythe filter-drier system cleaning procedure.

However, in the event a system is badly contami-nated (for example, if a water line ruptures in awater cooled condenser) it may be desirable topurge the system with dry compressed gas prior tostarting the final cleaning process. This not onlycan speed the cleaning procedure, but can reducethe contaminants to a level that can be handledeffectively by the necessary high vacuum equip-ment.

1. Disconnect the compressor and remove thelow pressure components (expansion valves,capillary tubes, controls, etc.) from the system.Install suitable jumpers in place of expansionvalves, capillary tubes, etc. and cap fittingsfrom which controls were disconnected. A pres-sure relief device preset at 175 psig must beinstalled in the supply line. (See Figure 158).

2. Dry nitrogen, dry carbon dioxide may now beintroduced into the system. The pressure regu-lator should be set to limit the pressure to 100psig.

3. Purge gas through the system until all freecontamination has been removed.

4. Close the cylinder gas valve, remove the pres-sure supply line, remove the jumpers, andreconnect the compressor and the low pres-sure components.

5. Install adequate filter-driers in the suction andliquid lines, pressure test, evacuate, and com-plete the system cleaning as necessary.

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HANDLING COPPER TUBING

Copper tubing is made for many types of usage,but tubing intended for plumbing or water pipe maycontain waxes or oils on the interior surface thatcan be extremely detrimental in a refrigerationsystem.

Dehydrated and sealed coil of soft copper tubing as itcomes from the manufacturer. Proper handling of tub-ing is necessary to obtain clean, dry systems.

Use only copper tubing especially cleaned anddehydrated for refrigeration usage. Soft coppertubing is available in rolls with the ends sealed, andhard drawn tubing is available capped and dehy-drated. Keep the tubing capped or sealed untilready for installation, and reseal any tubing re-turned to storage.

Examples of hard drawn copper tubing for refrigera-tion service. Note caps on ends to keep interior sur-faces clean during storage.

In the event hard drawn tubing is left open anddoes get dirty, draw a rag soaked in refrigerationoil through the tubing prior to usage.

BRAZING REFRIGERANT LINES

Refrigeration systems must be leak free, and theability to properly braze joints in tubing is anessential skill of the refrigeration serviceman.

Tubing should be cleaned and burnished brightbefore brazing. Care in cleaning is essential forgood gas-tight connections. Particular attentionshould be given to preventing metal particles orabrasive material from entering the tubing.

A suitable low temperature brazing flux that is fullyliquid and active below the flow point of the brazingalloy is required. Because of their nature, brazingfluxes are quite active chemically, and must bekept out of the system. Only the male connectionshould be fluxed, and only enough flux should beused to adequately cover the surface.

Applying flux to cleaned tubing before soldering. Fluxshould be applied sparingly and kept away from tubeend.

When heat is applied to copper in the presence ofair, copper oxide is formed. This oxide can beextremely harmful to a refrigeration system. Toprevent it s formation, an inert gas such as drynitrogen should be swept through the line at lowpressure during the brazing operation. Always usea pressure regulating valve in the line connectingthe nitrogen cylinder to the system.

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Courtesy E. I. DuPont de Nemours & Co.

Copper tube and fittings should be thor-oughly cleaned down to bare metal beforemaking soldered or brazed joint. Care incleaning will largely insure good, gas-tightconnections. Note tubing is pitched down-ward to prevent entry of abrasive particles.

Making silver soldered joint with fitting look-ing down. Whenever possible, solderedjoints should be made in this manner to keepflux and solder from getting inside. Note alsothat dry nitrogen is being swept through thetubing while soldering to prevent oxide for-mation.


The tubing should be properly supported so that nostrain is placed on the joints during brazing andcooling, and so that expansion and contraction willnot be restricted.

Apply heat evenly to the tube and fitting until theflux begins to melt. The way heat is applied caneither draw flux into the joint or prevent its entry.Apply heat around the circumference of the fittingto draw the brazing alloy into the joint to make amechanically strong and tight joint.

Never apply heat to a line under refrigerant pres-sure. The line may rupture, and the escapingrefrigerant pressure may throw blazing oil or mol-ten solder through the air. Refrigerants whenexposed to an open flame may break down intoirritating or poisonous gases.

Immediately after the brazing alloy has set, applya wet brush or cloth to the joint to wash off the flux.All flux must be removed for inspection and pres-sure testing.

SERVICE VALVES

With the exception of small, unitary, sealed sys-tems utilizing welded compressors, almost all re-frigeration and air conditioning systems have ser-vice valves for operational checking and mainte-nance access. Normally on accessible-hermeticcompressors, the compressor is equipped withsuction and discharge valves having service ports.Some systems may have service valves on lineconnections, receiver valves, or charging valves.

Figure 164 illustrates a typical compressor servicevalve, but valves of similar construction may beused for base valves, receiver valves, or chargingvalves. Note that there is a common connectionthat is always open, a line connection, and a gaugeport.

When the valve is back-seated (the stem turned allthe way out) the gauge port is closed and the valveis open. If the valve is front-seated (the stemturned all the way in) the gauge port is open to thecommon connection and the line connection isclosed. In order to read the pressure while thevalve is open, the valve should be back-seated,and then turned in one or two turns in order toslightly open the connection to the gauge port.

Some valves of the same general type intended forprocess access only may have only the line andgauge connections with the common port omitted.The action of the valve seat is unchanged. The lineconnection is closed when the valve is front-seated, the gauge connection is closed when thevalve is back-seated.

Figure 165 illustrates a Schrader type valve similarin appearance and principle to the air valve usedon automobile or bicycle tires.

The Schrader type valve is a recent developmentfor convenient checking of system pressures whereit is not economical, convenient, or possible to usethe compressor valves with gauge ports.

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This type of valve enables checking of the systempressure, or charging refrigerant without disturb-ing the unit operation. An adaptor is necessary forthe standard serviceman’s gauge or hose connec-tion to fit the Schrader type valve.

THE GAUGE MANIFOLD

The most important tool of the refrigeration ser-viceman is the gauge manifold. It can be used forchecking system pressures, charging refrigerant,evacuating the system, purging non-condensables,adding oil, and for many other purposes.

Basically the gauge manifold consists of com-pound and high pressure gauges mounted on amanifold with hand valves to isolate the commonconnection, or open it to either side as desired.Figure 167 shows a schematic view of a gaugemanifold with both valves closed. Figure 168illustrates the same manifold with the commonconnection open to the high pressure connection.The ports above and below each valve are inter-connected so the gauges will always register whenconnected to a pressure source.

The left hand gauge is normally a compound orsuction pressure gauge. The right hand gauge isthe high or discharge pressure gauge. Flexiblehoses are used to make connections from themanifold to the system.

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Gauges are fine instruments and should be treatedas such. Do no drop, keep in adjustment, and donot subject gauges to pressures higher than themaximum pressure shown on the scale.

Connecting the gauge manifold to a system is oneof the most common service functions. To avoidintroducing contaminants into the system, thehose connections must always be purged withrefrigerant before connecting the manifold. Aconsistent procedure should always be followedby the serviceman in making the connections. Foran operating system containing refrigerant, pro-ceed as follows:

First, back-seat the service valves to which thegauges are to be connected so that the gaugeports are isolated. Be sure both manifold valvesare closed (front-seated).

If operating conditions are such that the suctionpressure is certain to be above 0 psig, tighten hoseconnections to both service valves. Be sure com-mon hose connection on manifold is open.

Crack (open slightly) the high pressure manifoldvalve. Then crack the high pressure service valvethus allowing refrigerant to bleed through thedischarge and common hoses. Allow refrigerantto bleed for a few seconds, and then close the highpressure valve on the manifold. Repeat the same

procedure with the low pressure valves. The mani-fold is then connected to the system ready for use.

In the case of system where the low side pressuremight be in a vacuum, all purging must be donefrom the high pressure service valve. Back-seatthe service valves and tighten the hose connectionto the high pressure service valve. Leave hoseconnection at low side service valve loose and capor plug loosely the common hose connection.Crack both high and low pressure valves on themanifold. After a few seconds, tighten the hoseconnection at the low pressure service valve, andthen tighten the cap or plug in the common con-nection. Close the valves on the manifold, crackthe low pressure service valve, and the manifold isthen connected to the system ready for use.

PURGING NON-CONDENSABLES

A leak in the low pressure side of an operatingsystem frequently results in the entrance of air. Insome cases it may be impractical to remove therefrigerant charge and evacuate the system, yetthe air must be removed to prevent damagingchemical reactions.

Air is non-condensable under the temperaturesand pressures encountered in an air conditioningor commercial refrigeration system. The liquidseal at the outlet of the receiver and condenser willnormally trap the air in the top of the receiver andcondenser. The system condensing pressure willbe increased by the pressure exerted by thetrapped air, the amount of the increase in pressurebeing dependent on the quantity of air trapped.Before starting to purge, note the compressoroperating discharge pressure, and compare withthe temperature of the condensing medium.

Restart the compressor and check to see if thedischarge pressure is still abnormally high. If so,operate the system for a few minutes and repeatthe purging procedure. Normally purging 3 or 4times will remove most of the non-condensablestrapped in the top of the condenser and restorenormal operating pressures. However, purgingshould be used only as a short term emergencymeasure. In order to insure satisfactory compres-sor operation the system should be evacuated assoon as practical.

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SYSTEM PUMPDOWN

For any service work requiring access to thecompressor or the sealed part of the system, therefrigerant must first be removed. On small sys-tems without service valves, it may be necessaryto remove the refrigerant charge prior to servicingthe equipment, and then recharge the systemwhen put back in service.

On any system with service valves, the refrigerantcan be pumped into the condenser and receiver (ifused) and isolated there. This operation is termedpumping the system down, and is accomplishedby closing the valve at the outlet of the receiver orcondenser while the compressor is operating.Since no further refrigerant can flow to the evapo-rator, the refrigerant is pumped out of the evapo-rator and into the condenser.

Check the operating pressures by means of agauge manifold, (see Figure 166) and when thesuction pressure reaches 1 to 2 inches of vacuum,stop the compressor. (Note: If the unit is equippedwith a low pressure control having a higher setting,it will be necessary to bypass the low pressurecontrol in order to keep the compressor operatingwhile pumping the system down.) If the pressurerises rapidly, this is an indication that there is stillresidual refrigerant in the compressor crankcase.Start the compressor and again pump the suctionpressure down to 1 to 2 inches of vacuum. If thepressure remains at that point or rises very slowly,close the compressor discharge service valve. Inthe event the pressure should remain in a vacuum,disconnect power from the compressor, and crackthe receiver valve momentarily to introducesufficient refrigerant to obtain a slight positivepressure.

The liquid line, the low pressure side of the system,and the compressor should now be at a slightpositive pressure, (approximately 1 psig) and thatpart of the system can be opened for service. Therefrigerant pressure prevents the inrush of air intothe open system, and reduces contamination to aminimum.

Note that if it is necessary to remove or gainaccess to the discharge line, condenser, orreceiver, pumping the system down is of no ben-efit, and the refrigerant charge must be removedunless there are valves to isolate the defectivecomponent.

Pumpdown control is also used as a means ofisolating the refrigerant and preventing migrationto the compressor crankcase during periods ofshipment, storage, or long non-operating off cycles.

REFRIGERANT LEAKS

Refrigeration systems must be absolutely gastight for two reasons. First, any leakage will resultin loss of the refrigerant charge. Second, leaksallow air and moisture to enter the system.

Leaks can occur not only from joints or fittings notproperly made at the time of the original installa-tion, but from line breakage due to vibration,gasket failure, or other operating malfunctions. Arecent study by a major user of commercial equip-ment revealed that of approximately 3,000 servicecalls made during a typical year’s operation, 1 outof 6 were required because of refrigerant leaks.Since leak detection is such a common servicecomplaint, it is essential that the service engineercheck the system carefully to insure that it is leaktight before charging with refrigerant.

There are three common means of pressure test-ing a system for leaks. The pressure text methodinvolves pressurizing the system and checking forleackage outward.

WARNING — Never use oxygen for pressuriz-ing a system; an explosion may occur if oil ispresent in the system. Always use a gaugeequipped pressure regulator on the high pres-sure back-up gas, and never interconnect therefrigerant cylinder and the inert gas cylinderthrough a gauge manifold. Nitrogen and car-bon dioxide cylinder pressures can rupture arefrigerant cylinder.

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The electronic leak detector is the most sensitivetype available. These are available at reasonablecost, and can detect small leaks of a fraction of anounce per year, often missed when using othertesting methods. Because of their extreme sensi-tivity, electronic detectors can only be used in aclean atmosphere not contaminated by refrigerantvapor, smoke, vapor from carbon tetrochloride, orother solvents which may give a false reaction.

The leak detector most widely used for field ser-vice is the halide torch. It consists of a smallportable propane or L. P. gas tank, a sniffer hose,and a special burner which contains a copperelement. The gas feeds a small flame in theburner, pulling a slight vacuum on the sniffer hose.When the probe is passed near a leak, the refrig-erant is drawn into the hose and injected into theburner below the copper element. A small amountof refrigerant burning in the presence of copperhas a bright green color. A larger amount will burn

with a violet colored flame. When testing for leakswith a torch, always watch the flame for the slight-est changes in color. With experience, very smallleaks can be detected.

To use the halide torch to find a leak, explore eachjoint and fitting in the system. Check all gasketedjoints at the compressor. Some manufacturersuse the halide torch as a final check on packagedsystems which are shipped in cartons, by punch-ing a hole in the carton and checking inside thecarton several hours after the unit is packaged. Avery small leak will tend to build up in strength in anenclosed area, and can thus be detected.

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This type of detector is ideally suited for fieldservice of air conditioning and refrigeration equipment.

The oldest and probably most widely used leak detec-tor for fluorinated refrigerants is the halide type. Theone illustrated is made to attach to a small, portablegas cylinder. This makes a very compact, easy to use,leak detection device.


The simplest and oldest method of leak detectionis by means of soap bubbles. Swab a suspectedleak with liquid soap or detergent, and bubbles willappear if a leak exists. Despite its simplicity, thesoap bubble method can be extremely helpful inpinpointing a leak which is difficult to locate.

When a leak is located, it should be marked. Whenleak testing is completed and all leaks have beenlocated and marked, vent the test pressure gas. Ifa leak requiring brazing is found in the high pres-sure side of a system containing a refrigerantcharge, in a location that cannot be isolated, it willbe necessary to remove the refrigerant in order tomake repairs.

When pressure has been removed from the areawhere the leak is located, the leak can be repairedas necessary. It may be necessary to re-brazefittings, replace gaskets, repair flare connections,or merely tighten connections. When all leakshave been repaired, the system should again bepressurized and the leak testing process repeated.

Pressure leak testing is necessary to locate indi-vidual leaks. In order to determine if the system isfree of all leaks, a vacuum test is helpful. After

repairing all known leaks, draw a deep vacuum onthe system with a good vacuum pump. The pres-sure should be reduced to 1 psia or less (thevacuum registered on the test gauge will vary withatmospheric pressure) and the system should besealed and left for at least 12 hours. Any leakageof air into the system will cause the vacuumreading to decrease. (Some slight change in pres-sure may be caused by changes in ambient tem-perature). If an air leak is indicated, the systemshould again be pressure leak tested, and theleaks located and repaired.

When all leaks have been repaired and the systemsatisfactorily passes the leak tests, it is ready forevacuation and charging.

EVACUATION

Any time the compressor or system is exposed forprolonged periods to atmospheric air, or if thesystem becomes contaminated and removal of therefrigerant charge is necessary, the system shouldbe evacuated in the same manner as at the originalinstallation.

Liquid line filter-driers will effectively remove smallamounts of moisture from a system, but the amountof moisture in an open system may be greater thana drier’s capacity. In both cases, evacuation is theonly means of insuring a contaminant free system.

Under no conditions is the motor-compressor to bestarted or operated while the system is under ahigh vacuum. To do so may cause serious dam-age to the motor windings.

A small portable vacuum pump specifically built forrefrigeration evacuation should be used. Do notuse the refrigeration compressor as a vacuumpump. The serviceman who uses some discardedrefrigeration compressor as a vacuum pump isfooling himself and endangering the system.

The gauge manifold provides a convenient meansof connecting the vacuum pump to a servicevalves on the compressor or in the system, and isadequate for field evacuation of relatively smallsystems with small displacement vacuum pumps.For larger systems and larger vacuum pumps,however, the pressure drop through the hose

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Checking for refrigerant leaks with halide torch. Notesampling tube held adjacent to point of possible leak.Eye should be kept on flame to observe any colorchange.


connections on the normal service gauge manifoldis so high that evacuation is very slow, and gaugereadings may be misleading. Copper tubing orhigh vacuum hoses of ¼” I.D. minimum size arerecommended for high vacuum work.

Triple evacuation is strongly recommended for allfield installed systems because of the greaterdegree of contamination that must be expectedunder actual operating conditions as opposed tolaboratory or production line processing.

To evacuate a system with a small vacuum pumpand a gauge manifold, attach the common con-nection on the gauge manifold to the suctionconnection on the vacuum pump. The high andlow pressure connections on the gauge manifoldshould be securely connected to gauge ports onservice valves on the high and low pressure sidesof the system respectively.

With the valves on the gauge manifold closed(front-seated) open the service valves and adjustto a point approximately midway between thefront-seat and back-seat position.

Start the vacuum pump and gradually open thegauge manifold valves. It may be necessary torestrict the vacuum pump suction pressure bymeans of the gauge manifold valves to avoidoverloading the pump motor. Continue evacua-tion until the desired vacuum reading is obtainedon both gauges.

When evacuation is complete, close the gaugemanifold valves tightly, remove the line from thevacuum pump, and connect to a refrigerant cylin-der of the same type refrigerant used in the sys-tem. Loosen the common hose connection at thegauge manifold, crack the refrigerant drum valveto purge the hose, and retighten the hose connec-tion. Crack the valves on the gauge manifold untilthe system pressure rises to 2 psig. Close therefrigerant drum valve and the gauge manifoldvalves.

For triple evacuation, the above procedure shouldbe repeated three times, evacuating twice to 1500microns, and the last time to 500 microns, or to thelimit of the vacuum pump’s ability.

When complete, the system is ready for charging.If it is not to be charged immediately, the systemmay be sealed by back-seating the service accessvalves, and plugging or capping all open gaugeports or connections.

CHARGING REFRIGERANT INTO A SYSTEM

The proper performance of a refrigeration or airconditioning system is dependent on the properrefrigerant charge. An under-charged system willstarve the evaporator, resulting in excessively lowcompressor suction pressures, loss of capacity,and possible compressor overheating. Overcharg-ing can flood the condenser resulting in highdischarge pressures, liquid refrigerant flooding,and potential compressor damage. Most systemshave a reasonable area of tolerance for somevariation in charge, although some small systemsmay actually have a critical charge which is essen-tial for proper operation.

Each system must be considered separately, sincesystems with the same capacity or horsepowerrating may not necessarily require the same refrig-erant or the same amount of charge. Therefore itis important to first determine the type of refriger-ant required for the system, the unit nameplatenormally identifying both the type of refrigerantand the weight of refrigerant required.

Liquid Charging

Charging with liquid refrigerant is much faster thanvapor charging, and because of this factor isalmost always used on large field installed sys-tems. Liquid charging requires either a chargingvalve in the liquid line, a process fitting in the highpressure side of the system, or a receiver outletvalve with a charging port. It is recommended thatliquid charging be done through a filter-drier toprevent any contaminants from being inadvert-ently introduced into the system. Never chargeliquid into the compressor suction or dischargeservice valve ports, since this can damage thecompressor valves.

For original installations, the entire system shouldbe pulled to a deep vacuum. Weigh the refrigerantdrum, and attach the charging line from the refrig-erant drum to the charging valve. If the approxi-

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mate weight of refrigerant required is known, or ifthe charge must be limited, the refrigerant drumshould be placed on a scale so that the weight ofrefrigerant can be checked frequently.

Purge the charging line and open the cylinderliquid valve and the charging valve. The vacuumin the system will cause liquid to flow through thecharging connection until the system pressure isequalized with the pressure in the refrigerant cyl-inder.

Close the receiver outlet valve and start the com-pressor. Liquid refrigerant will now feed from therefrigerant cylinder to the liquid line, and afterpassing through the evaporator will be collected inthe condenser and receiver.

To determine if the charge is approaching thesystem requirement, open the receiver outlet valve,close the charging valve, and observe the systemoperation. Continue charging until the propercharge has been introduced into the system. Againweigh the refrigerant drum, and make a record ofthe weight charged into the system.

Liquid-charging refrigerant through the chargingvalve on main liquid supply line. Note that cylin-der is safely held in inverted position on weighingscale. Liquid shut off valve on receiver would alsobe throttled to facilitate flow from cylinder.

Watch the discharge pressure gauge closely. Arapid rise in pressure indicates the condenser isfilling with liquid, and the system pumpdown ca-pacity has been exceeded. Stop charging from thecylinder immediately if this occurs, and open thereceiver outlet valve.

On factory assembled package units utilizingwelded compressors, charging is normally accom-plished by drawing a deep vacuum on the system,and introducing the proper charge by weight intothe high pressure side of the system by means ofa process connection which is later sealed andbrazed closed. To field charge such systems, itmay be necessary to install a special processfitting or charging valve, and weigh in the exactcharge required.

Vapor Charging

Vapor charging is normally used when only smallamounts of refrigerant are to be added to a sys-tem, possibly up to 25 pounds, although it can bemore precisely controlled than liquid charging.Vapor charging is usually accomplished by meansof a gauge manifold into the compressor suctionservice valve port. If no valve port is available—forexample on welded compressors—it may be nec-essary to install a piercing valve or fitting in thesuction line.

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Vapor-charging refrigerant through compressor suctionservice valve. Gauges are connected to read both suc-tion and discharge pressure. When adding refrigerant,discharge pressure should be observed to be sure sys-tem is not over-charged and refrigerant is not beingadded too rapidly. Higher than normal discharge pres-sure indicates either that condenser is filling with liquidor compressor is being over-loaded by too rapid charg-ing. Charging manifold permits throttling of the vaporfrom the cylinder. Cylinder is mounted on scale to mea-sure amount of refrigerant charged. Approved valvewrench is being used to operate cylinder valve.

Weigh the refrigerant cylinder prior to charging.Connect the gauge manifold to both suction anddischarge service valves, with the common con-nection to the refrigerant cylinder. Purge the lines,open the refrigerant cylinder vapor valve, start thecompressor, and open the suction connection onthe gauge manifold. Modulate the rate of chargingwith the gauge manifold valve.

The refrigerant cylinder must remain upright withrefrigerant withdrawn only through the vapor valveto insure vapor only reaching the compressor. Thevaporizing of the liquid refrigerant in the cylinderwill chill the liquid remaining and reduce the cylin-der pressure. To maintain cylinder pressure andexpedite charging, warm the cylinder by placing itin warm water or by using a heat lamp. Do notapply heat with a torch.

To determine if sufficient charge has been intro-duced, close the refrigerant cylinder valve andobserve the system operation. Continue charginguntil the proper charge has been added. Againweigh the refrigerant drum and make a record ofthe weight charged into the system.

Watch the discharge pressure closely during thecharging operation to be certain that the system isnot overcharged.

How To Determine The Proper Charge

1. Weighing the Charge.

The most accurate charging procedure is to actu-ally weigh the refrigerant charged into the system.This can only be done when the system requires afull charge and the amount of charge is known.Normally such data is available on packaged uni-tary equipment. If the charge is small, it is commonpractice to vent the system charge to the atmo-sphere if repairs are required, and add a completenew charge after repairs are complete.

2. Using A Sight Glass

The most common method of determining theproper system charge is by means of a sight glassin the liquid line. Since a solid head of liquidrefrigerant is essential for proper expansion valvecontrol, the system can be considered properlycharged when a clear stream of liquid refrigerantis visible. Bubbles or flashing usually indicate ashortage of refrigerant. Bear in mind that if thereis vapor and no liquid in the sight glass, it will alsoappear clear.

However, if the service engineer should be awareof the fact that at times the sight glass may showbubbles or flash gas even when the system is fullycharged. A restriction in the liquid line ahead of thesight glass may cause sufficient pressure drop tocause flashing of the refrigerant. If the expansionvalve feed is erratic or surging, the increased flowwhen the expansion valve is wide open can createsufficient pressure drop to create flashing at thereceiver outlet. Rapid fluctuations in condensingpressure can be a source of flashing. For ex-ample, in a temperature controlled room, the sud-den opening of shutters or the cycling of a fan can

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easily cause a change in condensing temperatureof 10°F. to 15°F. Any liquid in the receiver maythen be at a temperature higher than the saturatedtemperature equivalent to the changed condens-ing pressure, and flashing will occur until the liquidtemperature is again below the saturation tem-perature.

Some systems may have different charge require-ments under different operating conditions. Lowambient head pressure control systems for aircooled applications normally depend on partialflooding of the condenser to reduce the effectivesurface area. Under such conditions a systemoperating with a clear sight glass under summerconditions may require a refrigerant charge twiceas large for proper operation under low ambientconditions.

While the sight glass can be a valuable aid indetermining the proper charge, the system perfor-mance must be carefully analyzed before placingfull reliance on it as a positive indicator of thesystem charge.

3. Using A Liquid Level Indicator

On some systems, a liquid level test port may beprovided on the receiver. The proper charge canthen be determined by charging until liquid refrig-erant is available when the test port is cracked.With less than a full charge, only vapor will beavailable at the test port.

Larger receiver tanks may be equipped with a floatindicator to show the level of liquid in the receivermuch in the same manner as a gasoline tankgauge on an automobile.

4. Checking Liquid Subcooling

On small systems, if no other easy means ofchecking the refrigerant charge is available, a de-termination of the liquid subcooling at the con-denser outlet can be used. With the unit runningunder stabilized conditions, compare the tempera-ture of the liquid line leaving the condenser withthe saturation temperature equivalent to the con-densing pressure. This provides an approximate

comparison of the condensing temperature andthe liquid temperature leaving the condenser.Continue charging until the liquid line tempera-ture is approximately 5°F. below the condensingtemperature under maximum load conditions. Thistype of charging is normally used only on factorypackaged systems, but it does provide a meansof emergency field checking which should indi-cate proper system operation.

5. Charging By Superheat.

On small unitary systems equipped with capillarytubes, the operating superheat may be used todetermine the proper charge.

If a service port is available so that the suctionpressure can be determined, the superheat maybe calculated by determining the difference between the temperature of the suction line approxi-mately 6 inches from the compressor and the satu-ration temperature equivalent of the suction pres-sure. If no means of determining pressure is avail-able, then the superheat can be taken as the dif-ference between the suction line temperature 6inches from the compressor and a temperaturereading on an evaporator tube (not a fin) at themidpoint of the evaporator.

With the unit running at its normal operating con-dition, continue charging until the superheat asdetermined above is approximately 20° to 30°. Asuperheat approaching 10° indicates an overcharged condition, a superheat approaching 40°indicates an undercharge.

6. Charging by Manufacturer’s Charging Charts.

Some manufacturers of unitary equipment havecharging charts available so that the proper chargemay be determined by observing the system op-erating pressures. Follow the manufacturer’s di-rections for determining proper charge if the unitis to be charged in this fashion.

REMOVING REFRIGERANT FROM A SYSTEM

Occasionally it will be necessary to remove re-frigerant from a system. To properly remove therefrigerant, the individual servicing the unit mustabide by the following guidelines.

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1. Complying with Law and Regulation

During the recovery, recycle and reuse of any andall refrigerants it is imperative that one complieswith current laws and regulations. It is the re-sponsibility of the individual servicing the refrig-eration unit to follow all current local, state, andfederal laws, regulations, and ordinances. It isalso their responsibility to follow any directions orguidelines that are set forth by the recovery unitequipment manufacturer.

2. Using the System Compressor

Connect the gauge manifold from the compres-sor discharge valve service port to the refrigerantcontainer and purge the lines. Note the maximumallowable refrigerant container weight.

Place the refrigerant container in ice. Place thecompressor in normal system operation. Turn thedischarge service valve in a few turns to open theservice port, open the refrigerant container valveand the gauge manifold so that discharge gas canenter the cold container, with the discharge pres-sure registering on the manifold high pressuregauge. WARNING. Do not close off the dischargevalve to the condenser. A portion of the dischargegas will now enter the container and condense.Weigh the container frequently to check theprogress in filling. Continue bypassing a portionof the discharge gas into the refrigerant containeruntil it is filled to its weight capacity. Do Not Over-fill. Use additional containers as necessary.

When a major portion of the refrigerant has beenremoved, system pressures may fall so low thatrefrigerant can no longer be efficiently transferred.

3. Using a Transfer Condensing Unit

A small, air cooled condensing unit equipped withan oil separator may be used as a scavenging ortransfer pump to transfer refrigerant to storagecontainers. By means of a gauge manifold con-nect system discharge and suction service portsto the transfer pump, and connect the transferunit liquid outlet connection to the refrigerant con-tainer.

Purge lines as previously outlined, start the trans-fer pump, and modulate the suction pressure asnecessary with the gauge manifold to preventoverloading.

WARNING. Watch refrigerant cylinder weightclosely. Do no overfill.

4. Charge Migration.

In the absence of a transfer condensing unit, andwhen the system compressor is inoperative, re-frigerant may be transferred to a storage containerby migration. Evacuate the container if possible,and connect to the system by means of the gaugemanifold.

Chill the refrigerant container to the lowest pos-sible temperature. Pack in ice or dry ice if avail-able. Open the valves so that the refrigerant canmigrate from the warm and therefore higher pres-sure system to the cold and lower pressure cylin-der. Do Not overfill.

Migration will continue until the system pressureis the equivalent of the saturated pressure of therefrigerant at the cylinder temperature. For ex-ample, if the cylinder is 40°F. and the refrigerantsR-12, migration will continue until the system pres-sure is approximately 37 psig.

A disadvantage of this system is the length of timerequired for the transfer.

HANDLING REFRIGERATION OIL

Oil processed for use in refrigeration compres-sors is highly refined, dewaxed, and dehydrated.In order top protect its quality, refrigeration oil isshipped in tightly sealed containers. Exposure toair and moisture for extended periods will resultin contamination of the oil, and can cause harm-ful reactions in the compressor.

Refrigeration oils are available in sealed contain-ers in various sizes, but should be purchased onlyin the sized container needed for the immediateapplication. It is highly recommended that oiladded to a compressor be taken only from sealedcontainers opened at the time of use. Do not trans-fer oil from one container to another, and do not

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store in open containers. Buying oil in large con-tainers to obtain a better price is false economy.In the long run, it will be far more costly in terms ofcompressor damage and customer ill will.

Compressors leaving the Copeland factory arecharged with Suniso 3G or 3GS, 150 SUS viscosityrefrigeration oil, and the use of any other oil mustbe specifically cleared with the Copeland Applica-tion Engineering Department.

DETERMINING THE OIL LEVEL

All service compressors are shipped with a chargeof the proper refrigeration oil. Normally the factoryoil charge in the compressor is somewhat greaterthan the normal oil level required for adequatelubrication, in order to provide some allowance foroil which will be circulating in the system duringoperation. Depending on the system design, theamount of oil in the system at the time of compres-sor installation, oil lost due to leakage, etc., it maybe necessary either to add or remove oil from asystem any time it is first placed in operation witha different compressor.

On Copeland compressors equipped with crank-case sightglasses, the oil level should be main-tained at or slightly above the center of the sightglass while operating. An abnormally low oil levelmay result in a loss of lubrication; while an exces-sively high oil level may result in oil slugging andpossible damage to the compressor valves orexcessive oil circulation. The oil level may varyconsiderably on initial start-up if liquid refrigerant ispresent in the crankcase, and the oil level shouldbe checked with the compressor running afterhaving reached a stabilized condition.

Most welded hermetic compressors have no meansof determining the oil level. This type of compres-sor is primarily designed for installation in factorydesigned, assembled, and charged systems wherethe oil charge can be accurately measured into thesystem at the time of original assembly. In the caseof a leak, if the amount of oil lost is small and canbe reasonably calculated, this amount should beadded to the compressor. If however, there is amajor loss of oil, the serviceman must remove thecompressor, drain the oil, and add the correct

measured charge before placing the compressorin operation.

ADDING OIL TO A COMPRESSOR

1. Open System Method

If the compressor is equipped with an oil fill hole inthe crankcase, the simplest means of adding oil isto isolate the compressor crankcase, and pour orpump the necessary oil in. If the system containsno refrigerant, or the compressor is open forrepairs, no special precautions are necessaryother than the normal measures of keeping the oilclean and dry, since the system should be evacu-ated prior to start-up.

If the system contains a charge of refrigerant,close the compressor suction valve and reduce thecrankcase pressure to approximately 1 to 2 psig.Stop the compressor and close the compressordischarge valve.

Remove the oil fill plug and add the requiredamount of oil. The residual refrigerant in thecrankcase will generate a slight continuing pres-sure and outflow of refrigerant vapor during theperiod when the compressor is exposed to theatmosphere, preventing the entrance of seriousamounts of either air or moisture. Purge the crank-case by cracking the suction service valve off itsseat for 1 or 2 seconds. Replace the oil fill plug,open the compressor valves, and restore thesystem to operation.

In the case of welded compressors installed insystems without service fittings, the only means ofadding oil to the compressor may be by cutting therefrigerant lines so that oil can be poured directlyinto the suction line since the suction connectionon a welded compressor opens directly into theshell.

2. Oil Pump Method

Many servicemen have either fabricated or pur-chased a small oil pump for adding oil to compres-sors. The pump is quite similar to a small bicycletire pump, and allows the addition of oil to anoperating compressor through the service port ifnecessary, or can be used to add oil directly to the

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crankcase where space may not permit a gravityfeed. When the compressor is in operation, thepump check valve prevents the loss of refrigerant,while allowing the serviceman to develop sufficientpressure to overcome the operating suction pres-sure and add oil as necessary.

3. Close System Method

In an emergency where an oil pump is not availableto the compressor is inaccessible, oil may bedrawn into the compressor through the suctionservice valve.

Connect the suction connection of the gaugemanifold to the compressor suction service valve,and immerse the common connection of the gaugemanifold in an open container of refrigeration oil.Close the manifold valve and the compressorsuction service valve and pull a vacuum in thecompressor crankcase. Then open the manifoldvalve, drawing oil into the compressor through thesuction service valve.

WARNING. Extreme care must be taken to insurethe manifold common connection remains im-mersed in oil at all times. Otherwise air will bedrawn into the compressor. On smaller horse-power or older style compressors where the suc-tion vapor and oil are returned directly into thesuction chamber, oil must be added very slowlysince drainage to the crankcase may be quiteslow.

Continue as necessary until the proper amount ofoil has been drawn into the compressor.

REMOVING OIL FROM A COMPRESSOR

Occasionally problems in line sizing or systemoperation may cause oil to trap in the evaporator orsuction line, and large amounts of oil may beadded to the system in an effort to maintain asatisfactory oil level in the compressor. When thebasic oil logging problem is corrected, the excessoil will return to the compressor crankcase, andunless removed from the system, can cause oilslugging, excessive oil pumping, and possiblecompressor damage. Also in cases where thesystem has been contaminated, for example by abroken water tube in a water cooled condenser, or

in cleaning a system after a bad motor burn, it maybe necessary to completely remove the oil from thecompressor crankcase.

To some extent the choice of a method for remov-ing oil depends on the degree of system contami-nation. For removing excess oil or on systems withonly slight contamination, almost any method isacceptable. However if the system is badly con-taminated, it may be advisable to remove thecompressor bottom plate and thoroughly clean theinterior of the crankcase.

1. Removing by Oil Drain Plug

Some compressors are equipped with oil drainplugs. If so, this provides an easy method forremoving oil.

Close the suction service valve, and operate thecompressor until the crankcase pressure is re-duced to approximately 1 to 2 psig. Stop thecompressor and isolate the crankcase by closingthe discharge service valve. Carefully loosen theoil drain plug, allowing any pressure to bleed offbefore the threads are completely disengaged.Drain oil to the desired level by seepage aroundthe threads without removing the plug.

When draining is complete, tighten the drain plug,open the compressor valves, and restore thecompressor to operation. The oil seal at the drainhole and the residual refrigerant pressure in the

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crankcase will effectively block the entrance of anymeasurable quantities of air or moisture into thesystem.

2. Removing by Oil Fill Hole

If a drain plug is not convenient or is not furnishedon the compressor, oil may be removed by meansof the oil fill hole.

Close the compressor suction service valve, re-duce the crankcase pressure to 1 to 2 psig, andisolate by closing the discharge service valve.

Carefully loosen the oil fill plug, allowing anypressure to bleed off before the threads are com-pletely disengaged. Remove the oil fill plug, andinsert a ¼” O. D. copper tube so that the end is ator near the bottom of the crankcase. If possibleuse a tube of sufficient length so that the externalend can be bent down below the crankcase, thusforming a syphon arrangement. Wrap a waste ragtightly around the oil fill opening, and crack thesuction service valve, pressurizing the crankcaseto approximately 5 psig, and then reclose thevalve.

Oil will be forced out the drain line, and will continueto drain by the syphon effect until the crankcase isemptied. If the syphon arrangement is not pos-sible, repressurize the crankcase as necessary toremove the desired amount of oil.

The residual refrigerant pressure in the crankcasewill prevent the entrance of any serious amounts oof moisture or air into the system. Purge thecrankcase by cracking the suction service valve offits seat for 1 to 2 seconds. Reinstall the fill plug,tighten, open the compressor valves, and restorethe compressor to operation.

In large systems where a large amount of excessoil must be removed, or where oil must be removedat intervals over a prolonged period, considerabletime can be saved by brazing a dip tube in a valveso that oil can be removed as desired as long asthe crankcase pressure is above 0 psig. (SeeFigure 175.) To speed up separation, the oilshould be removed to a ¼ sight glass level. Afteroil removal is complete, the oil level may then beraised to the normal operating level.

3. Removal by Means of Baseplate

On accessible compressors, it may be necessaryto remove the base plate if complete crankcasecleaning is necessary.

Pump the system down to isolate the compressor,remove the base plate, clean as necessary, andreinstall with new gasket. Since both air andmoisture can enter the crankcase during this op-eration, the crankcase should be evacuated with avacuum pump before restoring to operation. In anemergency, the crankcase may be purged bycracking the suction service valve and ventingthrough the oil fill hole and the discharge serviceport. Replace the plug in the oil fill hole and jog thecompressor a few times by starting and stopping,discharging through the discharge service port.Cap the discharge service port, open the dis-charge valve, and the compressor can be restoredto operation.

4. Removing Oil From Welded Compressors

If the oil must be removed from a welded compres-sor, for example to recharge with a measuredamount of oil, the compressor must be removedfrom the system, and the oil drained out the suctionline stub by tilting the compressor.

After the compressor is reinstalled the systemmust then be evacuated by means of an accessvalve or the process tube before recharging withrefrigerant and restoring to operation.

HANDLING FILTER-DRIERS

Regardless of the precautions of care taken, anytime a system is opened for repair or maintenance,some amount of moisture and air enters. In orderto avoid freezing of the moisture at the expansionvalve or capillary tube, and to prevent acid forma-tion and other detrimental system effects, themoisture level in the system must be kept at aminimum. Therefore every system opened forrepair or installed in the field must have a liquid linefilter-drier.

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Self-contained filter-driers or replaceable drier el-ements are factory sealed for protection. If theseal is broken and the drier is exposed to theatmosphere for more than a few minutes, the drierwill pick up moisture from the atmosphere and willquickly lose much of its moisture removal ability.

The system must be sealed and evacuated withina few minutes of the installation of the drier.Leaving a system open overnight after installationof a drier may completely destroy the drier’s value.

COMPRESSOR BURNOUTS - WHAT TO DO

(Excerpts from a speech by Raymond G. Mozley,Vice President, Application Engineering CopelandRefrigeration Corporation)

Sometimes we get so involved in the technicaldetails of how to solve a problem that we lose sightof the ultimate objective—how to get rid of theproblem. As the old saying goes, “We can’t see theforest for the trees.”

Our objective in any refrigeration or air condition-ing application is a satisfactory trouble free sys-tem. And, viewed from that standpoint, our answerto the question of compressor burnouts is at oncesimple and logical—prevent them before they oc-cur. Our ultimate objective is to prevent the occur-rence of a burnout, and this can only be donebefore a burnout occurs, not afterward.

It is true that occasionally a fault in the motorinsulation may result in a motor burn, but in asystem with proper design, manufacture, applica-tion, and installation, burnouts rarely occur. Ofthose that do occur, most are the result of me-chanical or lubrication failures, resulting in theburnout as a secondary result.

If the problem is detected and corrected I time, alarge percentage of compressor failures can beprevented. Periodic maintenance inspections byan alert serviceman on the lookout for abnormaloperation can be a major factor in maintenancecost reduction. It is far easier, far less costly, andfar more satisfactory to all parties concerned totake the few simple steps necessary to insureproper system operation than it is to allow acompressor failure to occur that could have been

prevented, and then have to restore the system tosatisfactory condition.

Probably no single type of failure has been morepublicized, more studied, more debated, and moreblamed for compressor failures than burnouts. Asa result of this widespread publicity, the burnoutproblem has been the whipping boy for othersystem problems of far more serious proportions,and in many cases has been blown up out ofproper perspective for competitive reasons. Atone time several years ago, motor burnouts werea serious problem in hermetic compressors, andeven today, many service engineers feel thatburnouts are a major source of compressor fail-ures. Our experience certainly indicates that dueto the tremendous improvements in compressordesign and system practices over the past years,burnouts as a cause of system failures ceased tobe a major factor several years ago.

Motor failures do occasionally occur as a result ofother malfunctions in the system, most often as anafter effect of a lubrication failure. This is one ofthe major factors which contribute to frequent fieldmisunderstanding of the type of compressor fail-ure which may have actually occurred. As a resultmany service personnel mistakenly attribute thecause of recurring failures to motor burns, whereasin reality the motor failure has been an after effectof other system difficulties.

If the service engineer is to help in eliminatingunnecessary compressor failures, he must thor-oughly understand both the operation of the sys-tem and possible causes of failure that mightoccur, and he must be on the alert for any signs ofsystem malfunction. On the return material cardswhich are attached to the compressors returned toour factory, a space is provided to note the causeof failure if known. On a great majority of the cards,there is a notation of bad compressor, compressorwon’t run, motor burn, or compressor locked up,and we suspect that the majority of these areclassified in the service engineer’s mind as com-pressor burnouts. The truth of the matter is that ofthe compressors returned to our factory during thewarranty period, probably 65% to 75% have faileddue to lack of lubrication or damage from liquidrefrigerant. Seldom do we see any notation to thiseffect on a return material card. We suspect that

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in the great majority of cases the serviceman didnot know what the cause of failure was, andinstalled a replacement compressor without deter-mining whether he had corrected the basic causeof failure.

System malfunctions rarely originate from normaloperation. They may be caused by some quirk insystem design, by contaminants left in the systemat the time of installation, by refrigerant leaks, bythe improper operation of some electrical or refrig-erant control components, or from a dozen otherpossible causes. In many cases, it may be a longperiod of time before the effects of some systemfault begin to affect the compressor operation. Inpractically every case, indications of a systemmalfunction are clearly evident prior to the com-pressor failure.

When A Burnout Occurs

But suppose, despite your best precautions, amotor burn does occur. What can you do? Hap-pily, today as a result of many years’ experience,techniques are available which make system clean-ing simple, effective, relatively inexpensive, anddependable.

The type of failure which has created the mosthardship on the user, and the one which hasreceived the most publicity in recent years hasbeen the repeat burnout type of failure, where theinitial burnout has triggered a series of failures onthe same system—each after decreasing periodof operation. It was recognized at an early stagethat contamination resulting from previous burn-out, remaining in the system, was the source of thesucceeding failure, but developing a dependablecure for the system was not an easy task.

Our company has been interested in cleaningmethods for a long time, and because of theproblems involved in the flushing process, we felta simpler, less expensive procedure was badlyneeded. Field experience in removing moisturefrom systems had indicated that filter-driers mightbe the answer.

In the early 1960’s in cooperation with major airconditioning and filter-drier manufacturers, we

launched an intensive field trial of the filter-driercleanout method. Basically this involved the use ofapproved filter-driers, incorporating an adequatedesiccant in both the liquid and suction lines.

A great deal of corporate money and prestige wasrisked in early field tests, but it paid off not only insuccessfully cleaned systems, but in developing abackground of test data so that we could safelyrecommend field proven components and knowthey would do the job. Several manufacturers arenow producing suitable filter-driers, and many ofthese have been proven by field experience to beof equal value in successfully cleaning systems.

Due to its simplicity, the cost of the filter-driercleanout system is quite inexpensive. There is noneed for large quantities of refrigerant for flushingthe system, no waste of man hours in laboriouslycleaning each circuit, no long periods of downtime. In most cases even the refrigerant in thesystem can be saved. This is the only practicalmethod which can assure proper cleaning espe-cially where long lines and multiple evaporatorsand circuits are involved.

This procedure has been used in thousands ofinstallations during the past few years, and whereproperly used we do not know of a single instanceof a second burnout due to improper cleaning. Wedo not feel there is any excuse today for repeatfailures due to improperly cleaned systems.

We do still get occasional reports of repeat failureson systems which have experienced a motor burn.In practically every case we find the system hasbeen improperly cleaned, in many instances be-cause the serviceman felt the system could becleaned merely by purging with refrigerant or byfailure to use the recommended suction line filter-drier.

We feel there is no such thing as a mild burnout.The only safe procedure is to treat every motorburn as a serious one. We do not agree with thosepeople in the industry who feel a system which hasexperienced a so-called mild burn can be safelycleaned by use of filters only in the suction line inconjunction with a liquid line filter-drier. In ouropinion the risks are far too great to gamble on ahalf-way cleaning job when the stakes are possible

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future costly trouble on the system, and the pos-sible savings are nominal at best.

Cleanout Procedure

The actual cleanout procedure with the filter-driersystem is quite simple.

A. Save Refrigerant

On any system the refrigerant charge should besaved if the volume is large enough to be worth-while. If the compressor has service valves, theremay be no need to even remove the refrigerantcharge. If a separate condensing unit or transferpump is available, flange adapters may be used topump the system down or pump the system chargeinto an empty drum. If a separate condensing unitis not available, in an emergency the replacementcompressor can be installed to pump the systemdown prior to the cleanout. Although some con-taminants will be returned to the compressor dur-ing the pumpdown procedure, the compressor willnot be harmed by the short period of operationrequired, and the contaminants will be safely re-moved as they are circulated through the systemafter installation of the system cleaner.

B. Remove Old Driers

All filter-driers previously installed in the systemmust be replaced, all filters or strainers cleaned orreplaced, and in the event of a bad burn, refriger-ant control devices such as expansion valves andsolenoid valves should be checked and cleaned ifnecessary.

C. Install New Filter-Driers

Adequate filter-driers of the proper size must beinstalled in both the liquid and suction lines. Thesuction line filter-drier is most important, sincecontaminants may not be effectively removed by aliquid line filter-drier alone. A pressure fittingshould be provided ahead of the suction line filter-drier, preferably in the shell, to facilitate checkingthe pressure drop across the filter-drier.

D. Check Electrical Circuits

All electrical connections should be checked to besure they are tight and properly made. Thecontactor should be examined, and any worn orpitted contacts should be cleaned or replaced. Onexternally protected motors standard service re-placement compressors are normally suppliedwith motor protectors mounted in the terminal box.No attempt should be made to salvage the externalinherent protector or external supplementary pro-tectors mounted in the terminal box of the com-pressor being replaced, as these might have beendamaged and could contribute to another failure.

If an electrical problem was responsible for theoriginal motor burn, and is not corrected, it canresult in the loss of the replacement compressor.

E. Place In Operation

The system may then be placed in operation, butshould be closely watched for at least two hoursafter start-up. As the contaminants in the systemare filtered out, the pressure drop across filter-driers will increase. Check the pressure drop acrossthe suction line filter-drier frequently. If the pres-sure drop increases to the point where it exceedsthe manufacturer’s recommended maximum limit,the filter-drier should be replaced.

F. 48 Hour Check

The system may then be allowed to operate for 48hours, at which time the color and odor of the oilshould be checked. Normally the system will beadequately cleaned by this time. However, if anacid content is present, if the oil is still discolored,or has an acid odor, the filter-driers should bechanged, and in the case of bad burns, the com-pressor oil should be changed. After an additional48 hours of operation, the oil should be checkedagain, and the filter-drier change repeated until theoil remains clean, odor free, and the color ap-proaches that of new oil. The suction line filter-drier may then be removed, preferably replacedwith a permanent suction line filter, the liquid linefilter-drier should be changed, and the system canbe returned to normal operation.

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Acid Check

Acid test kits are available from several manufac-turers for measuring the acid level in the oil. Theseare capable of making quite accurate acid mea-surements, but if they are not available, a check ofthe oil by sight and smell can give a quick indicationif contamination remains in the system. Sincerefrigeration oil varies in color, a sample of the newoil in the replacement compressor should be re-moved prior to installation and sealed in a smallglass bottle for comparison purposes. Suitable 2ounce bottles are obtainable at any drug store. Ifthe oil has been exposed to refrigerant, the bottleshould not be tightly capped, since the residualrefrigerant may create a high pressure if tightlysealed and exposed to high temperature.

Conclusion

In conclusion, let me stress again our answer tothe question of compressor burnouts. Preventthem before they occur. It is impossible to viewburnouts as a separate item, apart from the rest ofthe system. If you follow good refrigeration prac-tice, apply the compressor properly, keep thesystem free of contamination, and stay on the alertfor any system malfunctions, the burnout problemwill take care of itself.

COMPRESSOR FAILURES THAT COULD HAVEBEEN PREVENTED

To enable the user and service engineer to betterunderstand the type of damage that can occur inthe compressor from improper system control orexternal system malfunctions, the following typicalexamples illustrate mechanical damage from com-pressor failures that could have been prevented.

Liquid Refrigerant or Oil Slugging

Figures 176 and 177 are different views of a typicalvalve plate from a smaller horsepower compres-sor. A discharge valve and discharge valve backerassembly are shown in the foreground in newcondition for comparison. Note how the valvebackers on both discharge valves have been bentfrom the original shape. The backers are made of

steel, and only the force generated by a slug ofliquid refrigerant or oil would have sufficient impactto cause this distortion. Once the valve backer isbent, it is only a matter of time before the reed isbroken, since the reed is then subjected to stressesbeyond its designed strength.

The solution to this problem lies in proper controlof liquid refrigerant, and may require the use of asuction accumulator, crankcase heaters, or apumpdown cycle in a system with an excessivelylarge refrigerant charge.

Carbon Formation From Heat andContaminants

Figure 178 is a similar type valve plate showingextreme carbon formation. This occurs due to oilbreakdown, and can be caused by contaminantssuch as moisture and air in the system, or byexcessively high discharge temperatures. Con-trary to popular belief, carbon formation such asthis can occur without a motor failure.

This will not occur in a system that is properlycleaned, dehydrated, and evacuated, with motorand discharge temperatures maintained withinrecommended operating limits.

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Broken Discharge Reed

Figure 179 shows a discharge reed which hasbeen damaged by excessively high head pres-sures. Note the round hole which has been brokenout of the reed, and which actually has been forceddown into the discharge port. This occurs when thedischarge pressure builds up to a point at whichthere is sufficient pressure to actually shear thesteel discharge reed against the sides of thedischarge port in the valve plate on the pistonsuction stroke. Slugging is not necessarily con-

nected with this type of damage, and the valvebacker shows no signs of distortion. In order forpressure of this magnitude to build up it is probablethat either a restriction in the discharge line orliquid line—possibly in the refrigerant control de-vice—may have created a hydraulic pressure con-dition in the compressor discharge chamber.

Head pressures must be kept under proper controlfor the proper operation of any system. The pres-sures required to shear a reed in this manner arefar in excess of established compressor limits.

Ruptured Discharge Chamber

A discharge chamber from a Copelaweld com-pressor which has been ruptured by excessiveliquid pressure is shown in Figure 180. Note therelief valve on the end of the discharge chamberwhich will relieve pressures between dischargeand suction pressures to the compressor crank-case when the difference between discharge andsuction pressures exceeds 550 ± 50 psig. This willeffectively prevent gas pressures from exceedingthe relief valve setting, but liquid cannot be forcedthrough the valve quickly enough to prevent ex-cessive pressures. This type of damage will occuronly when excessive liquid slugging is taking place,or when excessive liquid in some way enters thedischarge chamber, and is normally encounteredonly when the system refrigerant charge exceeds

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the compressor charge limitation. Peak pressuresin excess of 2500 psig must have been experi-enced to cause this failure.

To avoid this type of damage, either the compres-sor charge must be kept within allowable limita-tions, or adequate safety provisions must be pro-vided in system design. Automatic pumpdownsystem control, suction line accumulators, or crank-case heaters may be required.

Connecting Rod Pinhole Wear

Figures 181 and 182 illustrate progressive stagesof connecting rod damage from wear of the con-necting rod pinhole. This condition occurs whenthe discharge valve is broken, and this piston issubjected to discharge pressure on both dischargeand suction strokes. As a result, the bottom side ofthe pinhole is always under pressure and receivesno lubrication. As the pinhole elongates, exces-sive play develops, and the connecting rod startshitting the underside of the piston. Eventual rodbreakage results, either at the pinhole, or at theconnecting rod shaft.

This type of failure normally is caused by dis-charge valve breakage. Usually it originates inliquid slugging or excessively high discharge pres-sures or temperatures causing the original valvedamage.

Piston

Damage Due To Lack of Lubrication

Figure 183 illustrates the condition of a piston afteroperating without adequate lubrication for pro-longed periods. This is most frequently encoun-tered on low temperature applications. This canoccur from excessive cylinder wall temperaturesresulting from high compression ratios and lowsuction pressures, or from inadequate air flow overthe compressor head and body. This same condi-

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tion can also result in any air conditioning orrefrigeration application from the continuous re-turn of liquid refrigerant, or an excessively wetmixture of liquid and vapor returning to the crank-case, which can wash lubricant from the cylinderwalls.

The oval shape resulting from piston wear isshown in Figure 184 and the eventual condition ofthe piston after failure due to contact with metalfragments is shown in Figure 185.

Crankshaft Damage Due To Lack ofLubrication

Scoring and wear of a crankshaft due to lack ofadequate lubrication is shown in Figure 186. Theridge on the one throw is due to wear from agrooved connecting rod. The heat generated inthe rods and bearings can cause eventual seizureof either rods or bearings, and possible connectingrod breakage.

To avoid damage to bearings, crankshaft, pistons,and connecting rods, continuous lubrication mustbe maintained at all times. Repeated short periodsof operation or prolonged periods of operationwithout adequate lubrication are almost certain toresult in compressor failure.

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Connecting Rod Damage Due To LiquidSlugging

While most Copeland compressors have alumi-num connecting rods which usually will breakrather than bend when subjected to excessivestress, some rods in older models of belt-drivecompressors are made with forged steel. Figures187 and 188 illustrate the distortion and bending ofthe steel rods caused by liquid slugging. This is anexcellent example of the tremendous force gener-ated by hydraulic compression when liquid refrig-erant enters the cylinders.

A refrigeration compressor is designed to pumpvapor only. While small amounts of liquid can betolerated, large amounts of liquid returning to thecompressor crankcase can cause major damage.Systems must be designed and applied so thecompressor is not subjected to such abuse.

System Cleaning with Filer-Drier

Copeland recommends only the filter-drier clean-ing procedure in the case of a motor burn. Basi-cally this involves the use of approved filter-driersincorporating an adequate desiccant (not a filteronly) in both the liquid and suction lines.

To illustrate the effectiveness of a suction linefilter-drier, 26 ounces of badly contaminated oilwere put in an operating system with a 10 H. P.compressor. Bottle #1 shows a sample of oilremoved from the system prior to the test. Bottle#2 is a sample of the contaminated oil introducedinto the system, which was then allowed to operatefor 24 hours without a filter-drier. The system wasthen equipped with a suction line filter-drier, and asample of the oil taken from the compressor at thistime is shown in Bottle #3. Sample #4 was takenfrom the crankcase one hour after the filter-drierwas installed, and Sample #5 was taken from thecrankcase 72 hours after the filter-drier was in-stalled. The oil has been effectively cleaned so thatthe color and appearance are equal to the originaloil.

This system cleaning procedure has been used inthousands of installations during the past fewyears, and when this procedure has been properly

followed, we do not know of a single instancewhere a second failure has resulted because ofimproper cleaning.

Discharge Valves Damaged From Slugging

Figure 190 shows a comparison of a new valveplate of the type used on larger compressors witha valve plate on which the discharge reeds anddischarge reed backstops have been damagedfrom liquid refrigerant or oil slugging. The back-stops are made of 1/8” hardened steel, and thedistortion clearly illustrates the tremendous forceexerted by the liquid or oil slug.

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Note that on the valves on which the backstopshave been badly bent, the discharge reed hasbeen broken, due to the resulting excessive stresson the reed.

PREVENTIVE MAINTENANCE

The question is frequently asked as to how long ittakes a compressor to wear out. It is almostimpossible to answer that question because sel-dom if ever does a compressor fail from wear dueto normal operation. Almost invariably a compres-sor failure results from malfunctions in either therefrigerant or electrical system, or from systemoperating conditions beyond the limitations of thesystem design.

Just what does this mean in terms of preventivemaintenance? In practically every case, indica-tions of a system malfunction are clearly evidentprior to the compressor failure. If the problem isdetected and corrected in time, a large percentageof compressor failures can be prevented. If theinspector is alert and on the lookout for any indica-tion that operation of the system is in any wayabnormal, a periodic maintenance inspection canbe a major factor in maintenance cost reduction.Inspections should be made at least three timesper year, and more frequent inspection is recom-mended during heavy usage periods.

Following is a summary of the major items to bechecked.

Check With Operating Personnel

Always check with the operating personnel whoare using the equipment to see if there have beenany reports of abnormal or erratic operation. Fre-quently indications of abnormal operation may beobserved by operating people who do not realizetheir significance, and this information may neverbe given to the service personnel unless broughtout by specific questions concerning system op-eration. Ask particularly about trips of the oilpressure safety control, or other safety devices.

Operating Pressures and Temperatures

If permanent gauges are available, check thecompressor suction and discharge pressures tobe sure they are within the normal range for theapplication and the temperature of the condensingmedium. If there are any indications of abnormaloperation such as short cycling on pressure con-trols or excessive compressor temperatures, usea gauge manifold to check the operating pres-sures on systems without permanently installedgauges.

If abnormal operating pressures are found, thecause must be found and the malfunction cor-rected.

Check the compressor head temperature by touch.An abnormally cool head can indicate a brokenvalve, a broken connecting rod, or excessive liquidrefrigerant flood back. An abnormally hot head can

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indicate a broken discharge valve, a blown orimproper head gasket, or inadequate compressorcooling.

Oil Level and Condition

On Copeland compressors, the oil level should beat or slightly above the center of the sight glass. Itshould be kept in mind that some slight fluctuationin oil level may occur during an operating cycle—particularly before and after defrost periods. Solong as the oil level is maintained well within thesight glass such fluctuations are not harmful.

If the oil is black in color, the crankcase should bedrained and the oil replaced. If there has been arecent compressor failure on the system and theoil has an acid odor, a fresh filter-drier should beinstalled in the suction line and left in the line for aperiod of 48 hours. If the oil is still discolored, thesuction line filter-drier is still discolored, the suctionline filter-drier element should again be changed.This procedure should be continued until the oilremains clean, odor free, and the color approachesthat of new oil. The filter-drier element may then bereplaced with a permanent type suction line filter.

It is recommended that only Suniso 3G or 3GS oilbe used in Copeland compressors. Unless thereare reasons as outlined above for changing the oil,the refrigeration oil should not be changed. It doesnot deteriorate or wear out with normal usage.

System Refrigerant Charge

All systems must have a full head of liquid refriger-ant at the expansion valve to insure proper opera-tion. A clear sight glass indicates an adequatecharge. Bubbles or flashing in the sight glass mayindicate a shortage of refrigerant, but flashing canalso be caused by a liquid line restriction, huntingexpansion valves, sudden changes in condensingpressure, and rapid changes in the refrigerationload. If there is a doubt as to the refrigerant charge,check the liquid level in the receiver. If no test cockis available, pass a torch flame momentarily backand forth on the receiver. If the metal remainsrelatively cool, a liquid level is indicated, but if themetal heats up rapidly, vapor is indicated. Theliquid level can be determined by the point wherethe temperature change occurs.

Units with roof mounted condensers equippedwith low ambient head pressure controls will re-quire a great deal more refrigerant for low ambientconditions, since the head pressure is normallymaintained by partially flooding the condenser.

Too little refrigerant can result in lack of refrigera-tion, loss of oil in the evaporator, and overheatingof the compressor. Too much refrigerant cancontribute to high discharge pressures, liquid re-frigerant flooding, liquid slugging, with resultingcompressor lubrication problems.

Special care should be taken in finding and repair-ing any leaks if a loss of refrigerant occurs.

System Control Settings

If there is any question as to the proper operationof the low pressure control, high pressure control,or oil pressure safety control, the pressure settingshould be checked. The accuracy of indicatingscales on refrigeration pressure controls is notdependable, and if operation is questionable, thecontrol should be checked with serviceman’sgauges.

Do not set the low pressure control below therecommended operating limits of the compressor.

The cause of any short cycling condition must becorrected.

If the operation of an oil pressure safety controls isquestionable, it should be checked by running ajumper connection across the pressure contactsto determine if the control will trip.

Liquid Line Filter-Drier

Check the color code of the moisture indicator. Apositive moisture indication indicates the filter-drier should be replaced.

If the drier is frosted or if there is a perceptibletemperature change between the liquid line enter-ing and leaving the drier, an excessive pressuredrop in the drier is indicated, and the drier or drierelement should be replaced.

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Vibration Eliminators

If the wire braid cover on a metal vibration elimina-tor is starting to pull out of the brazed end connec-tors, the vibration eliminator should be replaced toprevent possible rupture, loss of the refrigerantcharge, and potential personal injury.

Capillary Tubes and Refrigerant Lines

Check all capillary lines for wear and vibration.Tape or support as necessary. Check refrigerantline supports and braces to make certain they arenot wearing or cutting the refrigerant lines.

Oil traces at flare nuts or valve connections indi-cate the possibility of a refrigerant leak. Wipeclean and tighten the flare nut.

Liquid Refrigerant Control

Check for any indications of liquid refrigerant flood-ing such as sweating or frosting of the compressor,rust on the suction service valve or compressorbody, tripping of the oil pressure safety control,audible slugging, or excessive foaming in thecrankcase. If there is any question as to liquidcontrol, the operation of the system immediatelyafter a defrost cycle should be observed. Exces-sive sweating or frosting of the suction line and/orcompressor body must be corrected.

If the refrigerant cannot be properly controlled withthe existing system controls, a suction line accu-mulator may be required.

Suction Line Filter

Check pressure drop across suction line filter, andreplace element if pressure drop exceedsmanufacturer’s recommended maximum.

Electrical Control Panel

Check the electrical control panel to see thatheaters or motor protectors are not jumpered.Look for burn marks on the cabinet that mightindicate possible shorts, and check the contactson any contactor on which there is any question.

Air Cooled Machine Room

Check the exhaust fan and fan motor, and lubri-cate if necessary. Check operation of dampersand louvers, and lubricate as necessary. Run fanthrough on and off cycle by means of thermostat.

Remote Air Cooled Condenser

Check belt condition, and lubricate motor andshaft bearings. Clean condenser face if neces-sary. Inspect all line supports for vibration and linewear.

Walk-in Coolers, Freezers, Refrigerated Fix-tures

Check coils for ice build-up and cleanliness. Checktemperatures being maintained in refrigeratedspace. Inspect door latches, gaskets, moulding,etc.

Air Conditioning Air Handlers

Check filters and change if necessary. Check beltcondition and lubricate motor and shaft bearings.

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SECTION 27USEFUL ENGINEERING DATA

The following reference tables and charges cover miscellaneous data and conversion factors frequentlyrequired in engineering calculations. Data specifically pertaining to refrigeration has been included whereappropriate in previous sections.


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Form No. AE 105 R1Revised 1-05Emerson Climate Technologies and the Emerson Climate Technologieslogo are service marks and trademarks of Emerson Electric Co.Copeland Corporation is a registered trademark of Copeland Corporation.Printed in the USA. © 2005, 1970 Copeland Corporation.

1675 W. Campbell Rd.Sidney, OH 45365

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