air compresed piping

8/13/2019 Air Compresed Piping

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Hank van Ormer AIRPOWER USA 11520 Woodbridge LanePresident Baltimore, Ohio 43105

MODERN COMPRESSED AIR PIPING SELECTION AND DESIGN

CAN HAVE A GREAT IMPACT ONYOUR COMPRESSED AIR ENERGY DOLLARS

This paper introduces new concepts in compressed air piping, sizing, and system design beyondthe conventional pipe sizing charts and standard system layout guide lines.

The author shows how compressed air velocity has a very significant impact on the pressurelosses and piping performance. Case studies are used to show how conventional piping designand sizing keep extra compressors on line preclude proper control operation waste energy shorten filter life and have a negative impact on dryer performance.

The principles offered in this paper will help to trouble shoot old systems and help design new

systems. They will also help to avoid many common mistakes made over the last 30 to 35 yearswith the ascendance in popularity of the rotary screw compressor package.

Prepared for

Prepared by

Hank van OrmerPresident

AirPower USA, Inc.11520 Woodbridge Lane

Baltimore, OH 43105(740) 862-4112

www.airpowerusainc.com

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Proceedings of the Twenty-Seventh Industrial Energy Technology Conference, New Orleans, LA, May 10-13, 2005


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Have Any of These Things Happened to YouWith Regard to Your Compressed Air System?

Plant personnel say the current 200-hp compressor is too small and wont hold thesystem pressure. You purchase another 200-hp unit things get better but still seem tobe marginal?

Whats wrong? You doubled the air supply! Did you double production? If not, you should.The cost of your most expensive utility compressed air has significantly increased!

The compressed air supply is on the north end of the plant. You have trouble holdingpressure on the south end. Those in the know claim that because its so far downthere, we need to either raise the compressor discharge pressure (a significant energycost increase) or install another air compressor on the south end (often the first step inupsetting the system timing and efficiency!

The pressure problem isnt the distance its either the pipe sizing or system design or both.The most economical fix is usually a well-planned piping modification, which is a one time

cost. The other solutions may have a high initial cost or not but the related electrical energycost increase goes on year after year.

You run four lubricant-cooled rotary screws (total 400 hp) during full production for twoshifts and during the third shift, you still run the same four compressors (400 hp), eventhough the production is 50% or less during the third shift. You may run the same onweekends and holidays no one is sure. You have tried shutting a unit off, butsometime during the shift, it has to be manually turned back on in a hurry so you leaveit on.

The units have automatic start/stop controls, but they never turn off automatically. Youpurchase a new central control energy management system with great promise. You are

still running most of the units most of the time.

This is a more complex issue with several factors, but the root cause of the issue is often thepipe size and layout changes.

This list could go on and on with issues and opportunities fundamentally set up with improper orpoorly designed compressed air piping systems.

Over the last almost 20 years, we have reviewed almost 2,000 compressed air systems forenergy reduction and production and quality improvements. Our theories and ideas are nottheoretical they are based on field observation, and most importantly, on pre- and post-project measurement. The ideas and suggestions we present are not new many have been

lost or forgotten in transition. Compressed air is not complex, but the physics of compressedgases and the knowledge of the operating parameters of the equipment must be utilized withcommon sense.

Pipe size and layout design are the most important variables in moving air from the compressorto the point of use. Poor systems not only consume significant energy dollars, but also degradeproductivity and quality. How does one properly size compressed air piping for the job at hand?You could ask the pipe fitter, but the answer probably will be, What we always do, and oftenthats way off base.

AirPower USA, Inc. 1 www.airpowerusainc.com

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Another approach is matching the discharge connection of the upstream piece of equipment(filter, dryer, regulator, or compressor). Well, a 150-hp, two-stage, reciprocating, double-acting,water-cooled compressor delivers about 750 cfm at 100 psig through a 6-inch port. But most150-hp rotary screw compressors, on the other hand, deliver the same volume and pressurethrough a 2-inch or 3-inch connection. So which one is right? Its obvious which is cheaper, butport size isnt a good guide to pipe size.

Charts and Graphs

Many people use charts that show the so-called standard pressure drop as a function of pipesize and fittings, which sizes the line for the what is referred to as an acceptable pressure drop.This practice, too, can be misleading because the charts cant accommodate velocity- and flow-induced turbulence.

Some might call pipe sizing a lost art, butwe see the issue as a lack of attention todetail, basic piping principles, andguidelines. Read on to learn how to size air

piping using velocity, which when combinedwith appropriate piping practice, ensures anefficient compressed air distribution system.

As compressed air system consultants andtroubleshooters, we use certain guidelinesto design new piping systems and toanalyze existing system performance andopportunities for improvement.

There are four different categories ofcompressed air piping. They all have a job

to do, and therefore, require different designcriteria:

Inlet piping Interconnecting piping of the air supply Distribution piping headers/sub-headers Piping to feed the process.

As we look at each of these groups, we will list some of the rules of thumb or guidelines, whichare appropriate.

Inlet Piping

Guidelines: It is important to air compressor efficiency and integrity that the inlet is as cool aspossible, at as high pressure as possible, and free from contaminants such as dirt, pollen, birds,etc. and water.


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Inlet piping is often ignored today, because many of the fully packaged units have the intakeinside or on the package and take in room or ambient air. However, some plants will removethe room air intake (particularly when it is contaminated) and install a pipe to an outside-mounted filter for a more appropriate air source. Many larger compressors, such as centrifugalsor oil-free rotary screws, will have cooler outside inlet where the cooler inlet air has a muchhigher impact on performance efficiency then a lubricant-cooled rotary compressor.

When this happens, what size pipe? Dont size the pipe by the size of the inlet opening!

The objective is to deliver the air to the compressor inlet at the highest possible pressure after itleaves the outside intake filter or pick-up point. Like all piping, the pressure loss is a function offlow (scfm), pipe material, distance, and turbulence.

Size for negligible pressure loss by function it doesnt usually cost much to step up to the nextsize.

It can be good practice to provide a large volume

in the suction lines as shown here, just beforethe compressor intake flange. This will:

Act as a pulsation dampener

Trap any condensation (be sure to installdrain and trap).

Material: The proper inlet pipe brings the air from the filter to the compressor with no pressureloss and should not create operational problems with any type of self-contamination on theinside. It is important to realize that the ambient inlet air condition may well dictate the selectionof one type of pipe over another.

GALVANIZED INLET PIPINGhas the advantage of resisting corrosion better than standard ironpipe. However, over time when the corrosion does set in, the galvanizing material then peelsoff. The inlet pipe is now a producer of potentially very damaging, solid contaminants betweenthe filter and the compressor. This would be particularly dangerous to the mechanical integrityof a centrifugal compressor.

During high humidity weather, it is quite conceivable that condensation will form in the inletpipe (therefore, the OEM installation manual should recommend a drain valve be installed onthe pipe before the inlet). Condensation in the pipe will obviously accelerate the time framebefore the coating breaks down. This time frame is dependent upon where the thinnest portionof the coating is applied.

Stainless steel inlet pipeis the best possible material or such large-diameter, low-pressureinlet air, as long as it is installed properly and the inside is properly cleaned.


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There are also many grades ofplastic materialsuitable for inlet air piping.

Summary: We recommend either stainless steel or proper plastic-type material for inlet pipingand do notrecommend galvanized piping.

Design: Heres where common sense comes in:

Tight turns may cause pressure loss through turbulence run as straight and smooth aspossible and as direct.

We want the air to stay cool if you have to run the pipe into a hot room, or by a heat sourcesuch as a boiler -- then insulate it.

With reciprocating compressors, be sure you are not in critical length. Support the weight ofthe inlet pipe dont let it hang on the compressors.

Assuming the filter does its job on dirt, frogs, etc. as contaminants is there any chance ofinternal piping condensation. If so, just to be safe, install a drain point at the low point in the

inlet pipe just before it enters the compressor. On centrifugals and oil-free screws, we alwaysrecommend this drain.

Seem simple? All these moves seem logical and easy to follow, particularly having read theguidelines. We have corrected problems in all these areas time and time again in the field. Forexample, recently in a foundry, we found:

SULLAIR

20-

150L

SULLAIR

20-

150L

SULLAIR

20-

150L

1040 gal

Zurn RA 1400

Refer Dryer

FilterFilter Filter

Separator

Separator

Separator

FOUNDRY LONG SMALL INLET PIPE

2 2

2

3

150 HP 150 HP 150 HP

Inlet air to compressors 6 pipe260-300 ft measured vacuum 18Hg = 9.5 psia inlet pressure

assuming a normal 14.2 psia/inlet

pressure, this lowers the scfmfrom 725 scfm at 60F to 501scfm at 60 -- a loss of 31%volume per unit.

6 - 300 Ft of inlet pipe

To supply required 1400 scfm, theplant had to run one extra 150-hp full load estimated electricalenergy cost wasted -- $54,000

/year for 26 years = $1,400,000wasted energy!

Interconnecting Piping

This is the piping area where we find the most opportunities in compressed air systems,particularly in those installed after the late 1970s. The older systems were put in more carefullyand the introduction of lubricant-cooled rotaries created many misconceptions recommended bywell-meaning but untrained personnel.

Guidelines: the higher the pressure the compressor has to produce, the more electrical energyis required to run (1/2% per psig). With a few exceptions, the most energy efficient point for all


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compressors to run is at full flow. A well-designed and controlled system will have no more thanone unit at less efficient part load all others at full load or off.

The piping from the compressors to the filters, dryers, and the air receiver is what we call theinterconnecting piping. At todays recognized energy costs, its job is to get the air from thecompressor discharge to the dry air receiver (or system header, if there is no receiver with the

lowest possible pressure loss.

Part of this loss is filter and dryer selection, which is either implemented well or not. However,we often find significant problems, particularly in multiple compressor installations in pipe sizingand even more in layout or design.

Too much backpressure in the interconnecting piping can have many consequences, notimmediately obvious:

Reduce effective storage and cause short cycling in step-controlled units not onlywasting electrical energy, but also shortening the life of coolers, motors, air end, andcoupling.

Keep modulated-type controlled units from being fully loaded and subsequently runningmultiple units at plant load.

Cause the compressor to run higher pressure to deliver appropriate pressure to thesystem.

Line Pressure -- psigNominalPipe Size

CfmFreeAir 10 15 20 30 40 50 75 100 12 150 200 250 300 350

75 .19 .16 .13 .10100 .28 .24 .20 .16 .13 .11150 .69 .57 .49 .38 .31 .26 .19 .15 .12 .10200 1.20 1.00 .85 .66 .54 .46 .33 .26 .21 .18 .14 .11250 1.53 1.31 1.02 .83 .70 .51 .40 .33 .28 .21 .17 .15 .13300 1.89 1.47 1.20 1.01 .73 .57 .47 .40 .31 .26 .21 .18400 2.50 2.04 1.73 1.25 .98 .80 .68 .52 .42 .36 .31500 3.87 3.16 2.67 1.93 1.51 1.24 1.05 .81 .65 .55 .48600 4.50 3.81 2.75 2.15 1.77 1.50 1.05 .93 .79 .68800 4.87 3.82 3.13 2.66 2.04 1.65 1.39 1.201000 7.55 5.90 4.85 4.12 3.16 2.56 2.16 1.861250 9.12 7.49 6.35 4.87 3.96 3.32 2.871500 10.8 9.17 7.02 5.70 4.80 4.141750 12.5 9.54 7.74 6.50 5.622000 16.3 12.5 10.1 8.50 7.352250 15.8 12.8 10.8 9.30

2

Schedule40

2500 19.4 15.8 13.3 11.4

Most often, inexperienced compressed air system design personnel use only the StandardPressure Loss Charts (see above). These charts reflect pressure loss in piping what wenormally call friction loss the air pressure being lost to the friction on the pipe walls. As yousee, the chart is in psig loss per 100 of pipe based on flow (scfm) and entry pressure (psig).This is generally very accurate and satisfactory for distribution air, but in the interconnectingpiping, we have to consider another cause of pressure loss turbulence.


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Pressure Loss in Pounds for Each 100 Feet of Straight Pipe

The impact of turbulence on pressure loss is velocity dependent. If the air system designed isnot considering turbulence, then they are not up to modern times.

Interconnecting piping is usually short runs tying many pieces of equipment together, perhaps

with bypasses. It can become very convoluted.

Using only the standard pressure drop charts will indicate low friction loss of smaller pipe due tothe short runs. As the pipe selection gets smaller, the velocity increases. The velocity alsoincreases as the pipeline pressure falls.

These higher velocities, combined with some thoughtless piping practices by installers ordesigners not familiar with gas transmission, can lead to some very significant pressure lossesand completely upset the system. Often they run for years like this because the maintenancepersonnel cannot see any damage.

For example, the following schematic shows two separate compressor rooms in the same

foundry. Both have three 750 cfm @ 100 psig compressors. The piping dictated apparently bythe size of the connection is significantly different.

The large reciprocating units wereinstalled in 1968 6 discharge to a10 header with directional angleentry. The velocities are 7.9 fps to8.4 fps.

6

6

6

2 Discharge Line

2

2

2

3 Header

Three 150-hp Class

750-cfm Rotary Screw

Compressors

1978 units

Three 150-hp Class 750-

cfm ReciprocatingCompressors

1968 units

6 Discharge Line

Electric Cost of 18 psig @ .05

kWh / 8760 hrs = over

$60,000 /year wasted

The calculated pressure loss is lessthan 1 psig by the standardpressure chart and the actualmeasured pressure loss is less than

1 psig. This system is done by thebook and works fine.

The other system constructed in1978 (audited in 2001 & corrected)uses 2 lines to a 3 header withcrossing tee connection.

The velocities are 69.8 fps to92.6 fps.

The calculated pressure lossfrom standard charts is 8.0

psig -- relatively high, butacceptable at the time.

Actual measured pressureloss was 18 psig--10 psig ofimplemented pressure losswas turbulence-drivencaused by high velocities andcrossing tees.


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Typical Crossing Tee and Dead HeadAt higher velocities, these create significant turbulence-driven pressure loss

Directional Angle EntryA proper directional angle entry

1968 to 1978 What a Difference a Decade Makes!

The short cycling created by these high velocities and piping configurations basically helped to

cause the plant to run three 150-hp compressors when the original sizing called for two units.

At (.05 kWh @ 8760 hours 176 bhp this is a waste of over $60,000 /year in electrical energycosts for over 20 years -- $1,200,000!!

There are some verydistinct guidelines forpipeline velocity, which wehave found to work verywell in the real world.

Interconnecting pipingshould never exceed 20fps. There is no suchthing as too low velocity(or too large pipe) forthis application.

Avoid all dead heads,crossing tees, chokesfor flow meter uselarge enough pipe andlong ells.

At velocities below 20fps, design is much lesscritical.

1 Pipe

3 Pipe

2 Pipe

4 Pipe

All pipeline velocities to be

20 fps or less at 100 psig.

For Example:

56.8 scfm20 fps

220 scfm20 fps

492 scfm20 fps

838 scfm20 fps

Guidelines for Interconnecting Piping from Compressor s)through Filters, Dryers, etc. to System

6 Pipe 8 Pipe

10 Pipe 12 Pipe

1901scfm20 fps

5191scfm20 fps

3295 scfm20 fps

7368 scfm

20 fps

Use Long Ells

for turns.

Use 45odirectional (to flow)connection for two conjoining

air lines.

Crossing T

Dead Head

90o

Turns


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The Hidden Factor in Poor Interconnecting Piping

LOSS OF EFFECTIVE STORAGE

All air systems will do better with storage between the user and the process. Some types ofcontrol systems are more sensitive to lack of acceptable minimum storage than others.

The amount of effective storage for any control system is really a function of where theoperating control band (full load pressure to no load pressure) is equalized by the backpressurein the system.

If the compressor is setto full load at 100 psigand unload at 110 psigand pressure loss in theinterconnecting pipingand equipment reaches10 psig at the afterfilter

as in the figure at left.The effective storage is537 gals /71.84 cft. Thestorage value of thedistribution piping is notbeing utilized. This ismuch too small to allowefficient operation of thecompressor at full r

ange.

he example at right shows

op

ted

lons

500

gallon

Control Band 10psig

500 cfm

100 hp

66.84 cuft

1 cuft 1 cuft

3 cuft

4 Header

2000 ft

176.5 cuft

1321 gallons4 psid 4 psid

5 psid

EFFECTIVE STORAGE

71.84 cuft / 537 gallons

500gallon

Control Band 10psig


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Discharge Piping or Interconnecting Piping

Here we have more complex considerations:

Materials: The discharge air from the compressors can be at 250F to 350F (for centrifugal,oil-free rotary screw and reciprocating types), or from 200F to 220F (for lubricant-cooled rotary

screw compressors), so the pipe must be able to withstand those temperatures.

Even if there is an aftercooler that drops the temperature to 100F, consideration must be givenas to the consequences if the aftercooler were to fail.

Compressed air-generated condensate tends to be acidic. In oil-free compressors (such ascentrifugals and oil-free rotary screws), it is usually very aggressive.

The basic objective of the interconnecting piping is to deliver the air to the filter and dryers andthen to the production air system with little or no pressure loss, and certainly with little or no self-contamination.

Galvanized piping will have the same problems once it begins to peel as we described on theinlet application. In all probability, due to the aggressive acid characteristics of the condensate,the galvanized coating life may be much shorter.

Regardless of the plastic-type manufacturers claim, we never recommend any plastic-typematerial for interconnecting and distribution header piping. Most of these materials carrycautions not to be exposed to temperatures over 200F and to avoid any types of oil orlubricants.

Here again, stainless steel or appropriate copper is our number one recommendation for theinterconnecting piping from the compressor to the filter/dryers when the compressed air is oilfree. It will obviously resist corrosion much better than standard schedule 40 black iron. Some

other considerations:

Most areas will allow schedule 10 stainless steel in lieu of schedule 40 black iron.

For the same diameter pipe, stainless steel or copper will be much lighter and easier to handle,usually lowering the labor cost.

For welded connections, stainless steel usually just requires one bead, while black iron pipeusually requires three beads (weld-fill-cover). This should also lower the labor cost.

Stainless steel does not usually seal well when threaded. It will do much better with Victaulic-type connections when welding is not practical.

Distribution Piping: It is the job of the air distribution piping to deliver compressed air to allparts of the plant with little or no pressure loss. Should certain areas of the plant have surgedemands high flow demand over very short time frames it also has to handle this, feedingfull flow full pressure to that process and not pulling from other processes.


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D

6

111

2

1

1/2

1/2

1 Air Line fromCompressor Room 2

Air from Compressor

Room 2

Air from CompressorRoom 1

Dead Head

Drop at bottom of header

should be top

Crossing Tee

All processes total area fedby 1 small 1 drop

subheader

High Pressure Loss

Tie in at bottom of drop

should be -

Old abandoned Orifice Plate

Flow meter 3-5 psid

Air Leak

In this case, the headerpiping itself is acting as astorage vessel for theprocesssometimes asupplemental storagevessel (air receiver) at the

right location can be veryeffective if the headersare too small. This typeapplication has to beevaluated on a case-by-case basis.

Sizing Distribution Pipe:Modern thinking wouldcall for 0 psig pressureloss in the distribution bydesign. The real trick is

estimating how much flowcapacity is in any onesection at the highestpossible load.

Common Compressed Air Distribution Piping Mistakes

We start with what scenarios the average flow and size for 20 fps or less velocity (althoughmany feel up to 30 fps is all right and actually will work). Then we check for friction loss for themaximum flow at the largest runs. You will have to know or estimate accurately the processdemand for this.

As stated earlier, oversized header can act as storage and perhaps be the most economicalselection.

Oversized Header Pipingto create effective storage at the process. Often this can work, asshow below.

In Figure 1, the plant installed a large air receiver with an intermediate controller trying to hold acritical steady pressure at the regulator discharge for optimum production and quality. Therewas a 200 run of 4 pipe from the intermediate controller or regulator and the pressure variedfrom 85 to 90 psig as the regulator opened and closed randomly. The process regulators alsodelivered erratic pressure to blow off and usually well below the setting. The pull down band inthe main 4 feed was 4 psig. The regulator feed variance was much greater some well above10 psig.

The following actions were taken (see Figure 2):

Move receiver and intermediate controller closer to the process

Increase main feed line from 4 to 6 to eliminate pressure loss.

Oversize feeder header to the regulator to 12. This now created enough storage thatregardless of the timing of the regulated bursts of air, there was enough storage to feedeach line at full capacity without pulling the inlet pressure down at the nearby feeds oreven in the overall header.

AirPower USA, Inc. 10www.airpowerusainc.com

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3200 GAL

AIR PEELER

AIR PEELER

AIR PEELER

AIR PEELER

AIR PEELER

AIR PEELER

12

HEADER

5 OR 6 STRAIGHTFROM COMPPRESSOR

ROOM

85 PSIG

90 PSIG

72 PSIG

72 PSIG

72 PSIG

72 PSIG

72 PSIG

72 PSIG

Figure 2

AIR PEELER

AIR PEELER

AIR PEELER

AIR PEELER

AIR PEELER

AIR PEELER

4

HEADER

4 FROMCOMPRESSOR ROOM

MULTIPLE 90OTURNS

85-80 PSIG

59 PSIG

61 PSIG

65 PSIG

64 PSIG

68 PSIG

71 PSIG

Figure 1

Sometimes It Doesnt Work and You Need the Auxiliary StorageProvided by Properly Sized and Applied Air Receiver

The figure below is a process that feeds a large product collector requiring eight cubic feet of airin .75 seconds every five seconds.

AirPower USA, Inc.

Supply Air

CIP Solenoid

Instrument Air

Air to Pulsers

90-50 psig

Regulator

2 1 2

1/2

1 1/2

Cashco Regulators Check valve

Supply Feed from System

1

1 1/2

FilterRegulator

Filter

105 psig

The main 2 feed from the air system is at105 psig. The regulators and piping wereinstalled by the contractor. Each time theprocess runs, pressure quickly pulls downas low as 50 psig, which has very seriousnegative impact on productivity, productquality, and maintenance of the collector.

Regulator and piping sized to surgedemands as this must be sized on rate offlow:

Establish Rate of Flow: 8 cfm @ 0.75seconds =

8 x 60 sec 0.75 = 640 cfm rate of flow

11www.airpowerusainc.com

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Trying to use the pipe volume 2 and a quick response regulator did not work out:

No regulator has quick enough response to handle this 640-scfm rate of flow in 0.75 seconds,so we will supply the demand with storage and allow a metering valve to refill the receiver overa longer time frame (4 seconds), which will reduce the rate of flow from the air systemsignificantly.

Calculating maximum air receiver pressure loss 8 cfm demand in 0.75 seconds:

TDecay = (Storage Vol) (P2 P1) .(Net rate of flow) (14.5 psig)

0.0125 min = (V) (10 psig) = 10 V = 116 V = 11.6 cft or 86 gallons(0.75 sec) (640) (14.5)

Recommended action to deliver a consistent minimum pressure of 90 psig to the process duringpulsing (see figure below):

Remove 1 piping and both contractor-supplied regulators.

Install 2 piping to a metering valve (gate valve); adjust valve to refill the receiver in fourseconds after the pulser closes. Once set, remove handle to eliminate possibility ofinappropriate adjustment.

Install 120-gallon vertical air receiver to store at 100 psig or more.

Using a standard 120-gallon verticalreceiver (16 cu ft), we have the followingdrop:

Supply Air

CIP Solenoid

Instrument Air

Air to Pulsers

Regulator

2 2

1/2

1 1/2

Check valve

Supply Feed from System

1 1/2

FilterRegulator

Filter

2

MeteringValve

2

120

Gallon

105+ psig

90+ psig0.125 = 116x = 16 = 7.25 psig

Establish new rate for 4-second refill:

0.06 min = (16) (7.25) = 0.966x =(4 sec) x (14.5)

116 = 120 cfm rate of flow

Summary: the receiver, along with ametered flow allowing the receiver to

refill over four seconds, will reduce therate of flow from 640 cfm to 120 cfm.

There is not a regulator, which can react in the short amount of time in which the pulsers hit atthe required rate of flow. The receiver and metering valve will cushion the distribution pipingfrom this high rate of flow experienced by the system and the 2 main feed, thus allowing it tooperate correctly.


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Our piping modification shows a new metering valve sized to handle the new flow at 120 cfm.The bypass is piped with angle entry and exit around the metering valve. The process nowoperates correctly.

What we have had here are two downstream processes that require a little special attention.Until you get into the details, you cant be sure what the answer is. However, any surge

demand should be reviewed as to what effect it is having on the rest of the system and whattype of piping design it needs.

If the header is sized to 20 fps, not to exceed 30 fps, it will generally not have problems exceptfrom these type demands or over very long runs.

Loop design systems are always a good idea and often a system that has become restrictiveover time may be corrected by creating loops AFTER PROPER INVESTIGATION. There aremany other considerations, which are always discussed which we will not cover here centralized or decentralized system, top or side header connections, pipe slope, etc.

Be careful of subheader:

D7

6 Header

11

1

1

2

1

1/2

1/2

WATCH THE SUB-HEADERS

All of these processes fed by ONE 1 Feed

All of these subheaders are fed by a 1line. It is always easier to tie in on theend than hot tap or put another tapinto the main header. Often this canlead to very high pressure loss at theprocess.

Tip: When you build the main header,

put in extra taps, valved off on top andsides.

Like all things, the header systemseems simple until you start looking atwhat it has to do, what may be requiredin a Preliminary Investigation beforeactual design.

How Did Your Header Sizing Or Design Get Selected?

Drops to Process/Process Feeds

Again, this one seems simple feed to the process. Just attach to the top or side of the headeror subheader oops! where does the subheader get its air?


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16/22

Compressed Air Facts That Will Help to Keep the Process Air Clean and Dry

Use common sense: Typical application considerations that affect performance.

Many air systems we review withpoor air quality problems have

ignored some common sense rulesthat always apply. Keeping thesein mind will assure properperformance over a longer periodof time at a lower operating cost.

30+ Feet per Second Velocity:Virtually everything such as rust, scale, water and oil will carry down stream and into the element

Three basic rules on controllingwater contaminants before andafter the dryer, but ahead of a mline filter:

ain

Water vaporwill always move from an area of high relativehumidity to low relative humidity regardless of the direction of airflow. Dont ignore leaks.

Water

Vapor

Liquid wateralways drains down by gravity regardless ofair flow -- remember when piping and draining. Automaticcondensate drains on all risers with undried air.

DRY AIR

Liquid waterleft to stand in air receiver, filter housing, separators, low spots,etc., will evaporate into the dry air raising the relative humidity and pressure

dewpoint within the system. Drain condensate immediately and continuously.

Example -- Piping to Bagging Unit Regulator:

Original System Connection Corrected Connection

Liquid condensate drains into regulator Liquid condensate now drains from systemnegatively affects operation and life. pipe and regulator to automatic drain.

No changes to the compressed air system should be made wit r

Regulator gets no liquid.

Hose

Regulator

C

on

d

e

n

s

a

t

e

hout permission from the Compressed Ai

Pipe

Pipe

Regulator

Drain Point

FloorSupport

Czar. No equipment ordered unless the central air utility can handle or has plans to handle.

COMPRESSED AIR IS YOUR MOST EXPENSIVE UTILITY


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OTHER GENERAL PIPING & SYSTEM DESIGN GUIDELINES

NOT SPECIFICALLY COVERED IN MAIN PAPER

APPENDIX


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ESL-IE-05-05-10

air compresed piping

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