what you should know about refrigerant safety - quick reference handout

SAFE HANDLING OF REFRIGERANTS

COMPILED BY: TV VENKATASUBRAMANIAN

PROTECH ACADEMY, CHENNAI

THE HISTORY OF REFRIGERATION

HISTORY OF REFRIGERATION

The Use of Ice for Refrigeration purposes can be traced back to prehistoric times. Ice and Snow was often stored in areas that offered basic insulation to maintain low temperatures.

Cooling drinks came into vogue by 1600 in France. Instead of cooling water at night, people rotated long-necked bottles in water in which saltpeter had been dissolved. This solution could be used to produce very low temperatures and to make ice. By the end of the 17th century, iced liquors and frozen juices were popular in French society.

Before 1800, food preservation used time-tested methods: salting, spicing, smoking, pickling and drying. There was little use for refrigeration since the foods it primarily preserved — fresh meat, fish, milk, fruits, and vegetables — did not play as important a role in diets as they do today. In fact, diets consisted mainly of bread and salted meats.

19th Century

In the early 19th Century Ice became a form of business were It was sold for currency. Methods were improved to store ICE and ship it to warmer parts of the world.

By the Late 19th Century refrigeration became commercialised. Ice storage and usage was still the main form of chilling. This however came with its own problems such as contamination with unwanted substances. The general hygiene of Ice usage became a problem.

Post 1900's

At the turn of the 20th century the German engineer Carl Von Linde set up a large-scale process for the production of liquid air and eventually liquid oxygen for use in safe household refrigerators.

By 1900 ammonia-cycle commercial refrigeration was also introduced. By 1914 almost every location used artificial refrigeration. Refrigerated Transport by rail became available which revolutionised the safe transport of food and drink across countries.

In the middle of the 20th century refrigerated transport also began to be used on trucks and trailers which also made large improvements to consumer choice and hygiene.

Safety Issues

Despite the inherent advantages, refrigeration had its problems.

Refrigerants like sulfur dioxide and methylchloride if leaked can cause ilness and death. Ammonia had an equally serious toxic effect if it escaped.

Frigidaire discovered a new class of synthetic refrigerants called halocarbons or CFCs (chlorofluorocarbons) in 1928. Freons are colorless, odorless, nonflammable,

noncorrosive gases or liquids. Because Freon is non-toxic, it eliminated the danger posed by refrigerator leaks. In just a few years, compressor refrigerators using Freon became the standard for almost all-home kitchens.

Safe and more affordable refrigeration opened up new gateways in business for new types of food storage, packaging and presentation.

Though ice, brewing, and meatpacking industries were refrigeration’s major beneficiaries, many other industries found refrigeration a boon to their business.

In metalworking, for instance, mechanically produced cold helped temper cutlery and tools. Iron production got a boost, as refrigeration removed moisture from the air delivered to blast furnaces, increasing production. Textile mills used refrigeration in mercerizing, bleaching, and dyeing. Oil refineries found it essential, as did the manufacturers of paper, drugs, soap, glue, shoe polish, perfume, celluloid, and photographic materials.

Fur and woolen goods storage could beat the moths by using refrigerated warehouses. Refrigeration also helped nurseries and florists, especially to meet seasonal needs since cut flowers could last longer. Moreover, there was the morbid application of preserving human bodies. Hospitality businesses including hotels, restaurants, saloons, and soda fountains, proved to be big markets for ice.

Recent Refrigeration History

In 1973, Prof. James Lovelock reported finding trace amounts of refrigerant gases in the atmosphere. In 1974, Sherwood Rowland and Mario Molina predicted that chlorofluorocarbon (CFC's) refrigerant gases would reach the high stratosphere and there damage the protective mantle of the oxygen allotrope, ozone. In 1985 the "ozone hole" over the Antarctic had been discovered and by 1990 Rowland and Molina's prediction was proved correct.

As a result of the potential ozone layer damage. new technologies in refrigerants have been developed. The most popular are known as hydrofluorocarbons (HFCs), with an even lower global warming potential, and no known effects at all on the ozone layer.

Currently CFC's are being phased out and new refrigeration plants and appliances are being made with safer new generation refrigerants.

REFRIGERATION THEORY

Most people associate refrigeration with cold and cooling, yet the practice of refrigeration engineering deals almost entirely with the transfer of heat. A good definition of refrigeration is the removal of heat energy so that a space or material is colder than its surroundings. Heat is an energy which cannot be created, destroyed or seen however it can be moved.

This is one of the most fundamental concepts that must be understood. Cold is really only the absence of heat, just as darkness is the absence of light, and dryness is the absence of moisture.

"Cold is just the absence of heat"

Below is a basic diagram of how heat is displaced in a household refrigerator. The heat energy is drawn via the evaporator, it is then displaced at the external part of the fridge via the condenser into the cooler air.

THE ASPECTS OF REFRIGERANT SAFETY

REFRIGERANT SAFETY

The U.S. Environmental Protection Agency (EPA) cites environmental preservation as its motivation for the high degree of regulation in the air conditioning industry. Following EPA refrigerant regulations responsibly will contribute to the reduction of an environmental threat and protect organizations from civil penalties of up to $32,500 per day per violation and criminal penalties of up to five years imprisonment. For these reasons, it is important for engineering and maintenance managers that in-house service technicians and outside contractors working with refrigerants follow organizations’ written EPA policy and procedures. Well-defined procedures, appropriate

equipment, and sufficient knowledge of refrigerants will reduce accidents and injuries on the job, and training can make sure organizations achieve these goals.

TRAINING FOR COMPLIANCE

Although mandatory, safety and training are only parts of compliance. The EPA recommends that every organization designate a facility refrigerant compliance manager and implement a refrigerant compliance management plan. Producing a program that outlines organization-specific, written refrigeration regulations is the first step to effective compliance. It should describe how EPA regulations fit into an organization’s work processes and should use flow charts and work statements to illustrate key points. The program also should define the organization’s specific policies and procedures for refrigerant handling, from purchase through final disposal. Training is required within organizations to successfully implement an EPA refrigerant-management compliance program. A training program should ensure that everyone affected receives a copy of the compliance program and any other information needed to ensure success. The start of training is also a good time to reinforce management’s commitment to compliance. Also, employees should sign a statement of understanding that compliance is a condition of their employment, and managers should include these requirements in contractor agreements. To maintain ongoing compliance, managers also should schedule regular compliance update training. This step will reinforce the importance of compliance and further demonstrate an organization’s intent to comply.

INTEGRATING SAFETY

Section 608 of the Clean Air Act Amendments of 1990, as well as more recently proposed EPA amendments, require that technicians follow specific procedures while maintaining, servicing, repairing or disposing of air-conditioning or refrigeration equipment. Technicians can prevent injuries and costly mistakes by consistently following defined procedures and using common sense when handling refrigeration equipment. Taking simple precautions can be a substantial leap toward industry-wide safety. Among the more obvious practices that should become habit for refrigerant technicians are these. First, returnable cylinders must meet U.S. Department of Transportation (DOT) specifications and are characterized by a combined liquid/vapor valve located at the top. A returnable cylinder must never be filled above 80 percent of the container’s volume. If cylinders will be exposed to temperatures above 130 degrees, technicians should not fill them more than 60 percent. Hydrostatic pressure can be deadly in an overfilled refrigerant container. While over-pressure safety devices provide some level of safety, they do not eliminate risk. An opened valve can spew refrigerant, or the entire tank

might rupture with extreme violence. Second, technicians should weigh and inspect cylinders carefully before filling. They also should:

not use cylinders that are dented, rusted, gouged or damaged in any way examine the valve assembly for leakage, damage or tampering handle cylinders carefully store refrigerant cylinders in a vertical position with their valves at the top become familiar with all pieces of recovery equipment apply all methods and instruction prescribed by the system’s manual every time they use the equipment.

Disposable cylinders, which are constructed of common steel, can oxidize and become weakened by rust. As a result, their wall and seams no longer can tolerate pressure or contain gases. Technicians should discard rusted containers because they can never be used for recovery or refilling. To prevent corrosion, technicians should store containers in dry locations. Cylinders with residual refrigerant should not be allowed to sit at a job site because saturated vapor pressure will form if even the smallest amount of liquid is present. Before discarding a container, technicians should recover any remaining refrigerant per EPA recovery efficiencies. Third, technicians should collect used refrigerant in DOT-approved, refillable cylinders or drums, as appropriate, painted gray with the top shoulder portion painted yellow. They need to label the cylinder or container with a DOT four-by-four green, diamond-shaped, nonflammable gas label. Finally, technicians must fill drums to allow vapor space equal to at least 10 percent of the drum height between the top of the liquid and the drum top. Refillable cylinders must be retested and recertified every five years, and the test date must be stamped on the cylinder shoulder. Retesting by visual inspection alone is not permitted.

TRANSPORTING AND TRANSFERRING

In transporting used refrigerant, technicians need to clearly label its container with a DOT classification tag. When moving a cylinder, they must ensure that it is firmly strapped onto an appropriate wheeled device. Never roll a cylinder on its base or lay it down to roll it. Use a forklift truck to move half-ton containers of refrigerant. When transferring refrigerant from containers or equipment, it is mandatory to avoid contamination or venting to the atmosphere. Containers must be the correct type and color and properly marked. Any time a container or system undergoes the transfer of refrigerant, the technician must check it for refrigerant type, cleanliness and oils used. Also, the container used for

holding transferred refrigerant must be evacuated, and under no circumstances should workers mix different refrigerants.

TECHNICIAN PROTECTION

Chlorofluorocarbons and hydrochlorofluorocarbons are heavier than air and will replace air in a confined space. This situation can lead to possible asphyxiation for anyone working in the space. Oxygen starvation is the leading cause of death in accidents involving a refrigerant. Technicians must take extreme care to avoid direct ingestion of refrigerant vapors. If a spill occurs, they will need to put on a self-contained breathing apparatus or evacuate the area until it has been properly ventilated. Also, careless handling of cylinders can result in sudden releases of refrigerant, which can cause frostbite, skin damage or blindness. To avoid these circumstances, workers should wear safety glasses with side shields or a full-face shield, safety shoes, hard hat, long pants, gloves and a long-sleeved shirt. Workers can prevent accidents around hoses and extension cords by using proper barriers and signs. Use top-quality, properly attached hoses and lines, place them where risk is minimal, and inspect hose seals frequently. Wear butyl-lined gloves and safety glasses when working with hoses. Technicians also can enhance safety by:

ensuring that all power is disconnected and disabled to any equipment requiring recovery locking out disconnects with approved lockout devices opening valves slowly and knowing in advance if liquid vapor will be released not plugging pressure-relief devices never applying direct heat to a closed system that contains refrigerant.

Finally, installing refrigerant vapor sensors, an adjoining alarm system, ventilation piping leading from the purge units to the outside air, and ventilation exhaust fans can increase the safety of a system.

What You Should Know About Refrigerant Safety??

Taking precautions when working with any refrigerant can help avoid dangerous situations and injuries

An HVACR technician is exposed to many personal safety hazards during the course of a normal workday. In addition to the obvious hazards such as sharp metal, electrical wiring and climbing ladders, the technician needs to be aware of the safety hazards that refrigerants pose.

Refrigerant safety is straightforward: If the refrigerant stays contained in the cylinder or in the system then it presents little danger to people. The hazard occurs when the

refrigerant comes out of the container or system, often quickly and unexpectedly. Injuries can be avoided if regular safety checks are performed.

Regular checks on containers and systems for holding pressure, and preparing safety equipment and procedures to minimize personal exposure after unexpected releases should help avoid any injuries when handling refrigerants.

Specific hazards from refrigerant fall into three categories: toxicity, combustion/flammability/decomposition, and pressure.

BODY’S DEFENCE -

Toxicity and personal exposure

Most refrigerants have undergone extensive toxicity testing before being released for general refrigeration or air conditioning use. Testing generally involves a range of exposure levels and times to determine any possible effects on test animals. Short term exposures at high concentrations indicate any acute hazards such as irritation, sensitization of the heart or adrenaline and lethal concentration (LC50 is the amount which kills half the animals in a short amount of time). Tests that expose animals for longer periods of time, such as 90 days to two years, are designed to indicate chronic problems. These can include mutagenicity (changes to cells), reproductive problems, effects on organs or carcinogenicity (cancer-causing). ASHRAE Standard 341 provides a safety classification for refrigerants based on information related to personal exposure. ASHRAE Standard 152 uses this safety rating and additional toxicity information to set requirements for machinery rooms and sets limits on the amount of refrigerant allowed in systems outside machinery rooms. Many blends containing these individual components are also classified.

Refrigerants not classified in ASHRAE Standard 34 should be reviewed with suppliers to make sure enough is known about their toxicity properties. Some blends may not be classified, but contain classified components. (Note: Many building codes have adopted the newer refrigerants listed in ASHRAE standards. Some building codes have not, and therefore, require special permits. A refrigerant that's not listed most likely will require an engineering study to determine if it can be used safely.)

Exposure levels are values given to refrigerants to indicate how much of the chemical a person can regularly be exposed to without adverse effects. All toxicity test results are considered when setting this level. The American Conference of Government and Industrial Hygienists (ACGIH) sets the TLV-TWA values for chemicals. TLV-TWA stands for Threshold Limit Value-Time Weighted Average, which is the amount of chemical a person can be exposed to for 8 hours a day, 40 hours a week, without adverse effects.

The maximum value for any chemical is 1,000 ppm, though many refrigerants have shown no effects in toxicity testing at values much higher than that. Other organizations and chemical producers have similar exposure level indexes based on the same criteria. These are the Workplace Environmental Exposure Limit (WEEL) set by the American Industrial Hygiene Association (AIHA); Permissible Exposure Limit (PEL) set by OSHA; and Acceptable Exposure Limit (AEL) used by DuPont.

There are also the Short Term Exposure Limit (STEL), which is based on a 15-minute exposure time in any given day as well as the value Immediately Dangerous to Life or Health (IDLH). These are used to give guidance for machinery room requirements, ventilation and alarms in an emergency or escape situation, or in circumstances where short releases of refrigerant are expected, which could include refrigerant transfers or servicing large equipment.

Toxicity data is usually summarized in great detail on Material Safety Data Sheets (MSDS). What all of this data means to the technician, however, is that commercial refrigerants are safe enough to use provided you don't breathe too much of them. Industry practices for handling refrigerant are intended to minimize personal exposure as well as reduce releases into the atmosphere.

General rules to follow are:

- Minimize the amount of refrigerant released. Proper recovery procedures, including clearing hoses, will keep the refrigerant in the containers instead of potentially exposing it to people. - Never intentionally release refrigerant in a confined space. Even the safest refrigerant can still displace enough oxygen to cause suffocation. Set up ventilation equipment, like a portable fan, in areas where possible release would mean high concentrations. - Refer to ASHRAE Standard 15 and local building codes for additional guidance. If someone is exposed to refrigerant get him to fresh air, give oxygen if needed, and get him checked by a doctor.

OCCUPATIONAL EXPOSURE LIMITS

The maximum concentration of an airborne substance averaged over a reference period to which an employee may be exposed by inhalation

Flammability Combustion/Decomposition

Flammable refrigerants present an immediate danger when released into the air. The refrigerant can combine with air at atmospheric pressure and ignite, causing a flame and possibly an explosion to occur. Because of the obvious hazards, the use of flammable refrigerants is restricted to controlled environments that have monitors, proper ventilation, explosion-proof equipment and generally few people near the equipment (refineries, storage warehouses, breweries, etc.).

Some refrigerants can burn with oxygen, but only at higher pressures or temperatures and never in air at atmospheric conditions. These are called "combustible" refrigerants. Underwriter's Laboratories (UL) lists these refrigerants as "Practically Nonflammable."

R-22 and R-134a fall into this category. R-22 was found to cause a combustion hazard during a pressurized leak test with air. For this reason, most refrigerants should be used only with pressurized nitrogen for leak testing. As long as refrigerant is not mixed with large amounts of air, there should be little hazard from these refrigerants during normal handling and use.

Decomposition can occur with any refrigerant when it gets hot enough (generally above 7000° F). Refrigerant can decompose in systems or containers exposed to fire or other extreme heat, electrical shorts (burnouts), or in refrigerant lines being soldered or brazed without being cleared first. Obviously, refrigerant containers or charged systems should never intentionally be exposed to a flame or torch.

When a refrigerant is decomposed or burned, the primary products formed are acids: Hydrochloric acid (HCI), if the refrigerant contains chlorine, and hydrofluoric acid (HF), if it contains fluorine. These products are certainly formed when hydrogen is present, such as from the breakdown of oil, water or if the refrigerant has hydrogen attached (like R-22 or R-134a). If oxygen also is present (from air or water), then it's possible to form carbon monoxide, carbon dioxide and various unsaturated carbonyl compounds -- the most notorious of which is phosgene.

Being extremely toxic in small amounts, phosgene formation was a real concern when traditional refrigerants (R11, R- 12, R- 113, R- 114) decomposed. Phosgene contains two chlorine atoms and an oxygen atom. It will only form when oxygen is present and only the refrigerants with chlorine attached will produce phosgene (not HFCs). R22 has only one chlorine atom per molecule, so it is extremely difficult, chemically speaking, to get another one attached to form phosgene. Decomposition of R-22 or HFCs may form other carbonyl fluorides, however they are not as toxic as phosgene.

The standard practice for handling decomposed refrigerant is to collect the gas, treat the refrigerant and/or the system for acid contamination, and appropriately dispose of the burnt gas. Please note that any cylinder or system component exposed to high heat or fire should be retested or discarded. Cylinders used to recover burnt gas should be checked and cleaned before being put back into service, especially the valve and/or pressure relief device.

Physical hazards The fact that it's a liquified gas under pressure is one of the more obvious hazards of refrigerant. Sudden, unexpected release of pressurized refrigerant can result in personal injury.

Frostbite.

Liquid refrigerant suddenly released from high pressure to atmospheric pressure will flash and boil to vapor. Naturally, the temperature of the refrigerant will drop quickly to the boiling point and the refrigerant will quickly absorb heat from whatever it is touching. If the refrigerant is touching skin it can cause frostbite. Frostbite damages skin by freezing water inside the skin cells, which can expand and burst the cell walls. To treat frostbite cover the exposed area with warm (not hot) water or a wet compress. The skin must recover slowly or more damage can occur. Do not rub the affected area to try to warm it as it may inflict more damage. Protective clothing, gloves and eye protection are effective at preventing frostbite by keeping liquid refrigerant away from the skin.

Rupture of tank or system.

Cylinders or systems without pressure relief devices could break if the refrigerant pressure inside were to exceed the strength of the cylinder or system component. This type of failure can be quite hazardous if the refrigerant is at a high pressure or solid material is blown loose. Containment failures are caused by one of two things: The refrigerant pressure has increased above the pressure rating of the cylinder or system, or something has happened to the cylinder or system so that it will no longer hold normal refrigerant pressure.

Elevated refrigerant pressure can be caused by exposure to heat. Refrigerants with pressures similar to R-12 will develop more than 500 psia at temperatures above 200° F. Refrigerants with pressures similar to R-502 will achieve the same pressures at about 150° F. Hydrostatic pressure also can develop quickly in a confined volume that has been completely filled with liquid refrigerant, for example liquid-full hoses between shut valves or an overfilled recovery cylinder.

Refrigerant tubing, hoses, system components and some refrigerant cylinders surely would fail at some elevated pressure without certain safety provisions. Various pressure relief devices are used to lower the pressure back to safe limits by releasing some or all of the refrigerant.

Valves on many refrigerant cylinders are fitted with spring-loaded pressure relief valves. These are typically set to release pressure somewhere above typical refrigerant pressures at normal use or transportation temperatures, but below the maximum service pressure of the cylinder. When the pressure is reduced to a safe level the valve should close itself.

Other cylinders or storage vessels are fitted with burst discs as the pressure relief device. These are pieces of metal designed to break at some preset pressure, again lower than the maximum service pressure of the container. In the case of a burst disc, the entire contents of the container will be released. This is also the case with a fusible plug, which is designed to melt at a certain temperature. It's used to relieve the pressure in a tank or system in a fire situation before the pressure gets high enough to burst the tank, tubing or system component.

Damaged or weakened refrigerant cylinders or system components may fail at pressures lower than originally specified. Physical abuse such as dents, scratches, rust, bulges or exposure to excessive heat can reduce the strength of joints or the metal

itself. Materials originally designed to hold hundreds or thousands of psi pressure might now fail at typical refrigerant pressures. In the case of damaged cylinders, the pressure relief device shouldn't be relied upon for protection; the cylinder should be repaired and retested or discarded.

The best way to avoid pressure-related hazards is to always use cylinders and system components that have the correct pressure rating for the refrigerant you're using. Table 1 lists the typical cylinder service pressures that manufacturers and distributors use for various refrigerants. Pressure ratings for system components must be chosen based on the application and expected service pressures for the intended application. Pressure ratings are also based on the refrigerant chosen. Always check for signs of damage or excessive wear before filling recovery cylinders, picking up new refrigerant cylinders or attaching new parts to a system.

FREON REFRIGERANT - SAFE HANDLING PROCEDURES

Safety information 1. Any crew member, who discovers that there is a Freon leak must Move to an area of fresh air and warn other crew members; Inform the chief engineer immediately; Open up windows and doors and ventilate the space using fans or blowers, if practicable; If he feels any unusual health effects, seek medical advice. 2. All crew members should be aware of the hazards which may be associated with handling of refrigerants on board. 3. Freon vapour is heavier than air and may accumulate in low-lying areas, at deck level, displacing oxygen and posing an asphyxiation hazard. 4. Odour is not an adequate indicator of the presence of Freon and does not provide reliable warning of hazardous concentrations. 5. Freons are generally non-flammable and non-combustible, however, when involved in a fire or in contact

with heated surfaces (>480°C), Freons decompose producing hydrogen chloride, hydrogen fluoride,

phosgene, and chlorine. All of these decomposition products are acutely toxic and are very hazardous even in low concentrations. 6. Freons are incompatible with perchloric acid, chromium trioxide, nitric acid, chemically active metals (such as aluminium and zinc), alkali metals (such as sodium and potassium); and alkaline earth metals (such as beryllium, magnesium, and calcium). 7. Freons generally have a low order of toxicity. However, exposure to relatively high concentrations (>100 ppm) may produce adverse effects on health. Possible exposure routes include inhalation, ingestion, skin and eye contact. 8. Freon vapour may cause irritation of the eyes, nose, throat, and mucous membrane at low concentrations. At high concentrations, Freon vapour may cause pulmonary oedema and neurological problems such as central nervous system depression, dizziness, headache, drowsiness, tremors, seizures, confusion, lack of coordination, loss of consciousness, and paralysis. 9. Inhalation of high concentrations may also result in temporary alteration of the heart’s electrical activity. The sensitivity of the

heart to the arrhythmogenic action of epinephrine will increase, causing irregular pulse, palpitations, or inadequate circulation. Deliberate inhalation (‘sniffing’) may cause death without warning.

10. At extremely high concentrations; several thousand parts per million (ppm), Freon vapour has the potential to reduce the amount of oxygen available for breathing, especially in confined spaces, which can lead to asphyxiation. 11. Skin contact with liquid Freon can cause frostbite. Repeated skin contact with Freon gas may also cause drying with rashes. 12. Chronic exposure to Freon may produce weakness, pain, and paresthesias (a sensation of numbness, tingling or burning) in the legs. Chronic fluorocarbon exposure has been linked with motor, memory and learning deficits. Long-term inhalation of high concentrations may also lead to abnormal liver function with hepatic lesions.

First aid 1. Eyes - If eye tissue is frozen, obtain medical attention immediately. If eye tissue is not frozen,

immediately flush eyes with large amounts of water for at least 15 minutes, occasionally lifting the lower

and upper eyelids. If irritation, pain, swelling, tearing, or sensitisation to light persists, obtain medical attention as soon as possible. 2. Skin - If frostbite has occurred, do not rub the affected area. Flush with water or remove frozen clothing

from frostbitten area and seek medical attention immediately. Otherwise, immediately remove contaminated clothing and wash contaminated area with soap and water for at least 15 minutes. Seek medical attention, especially if redness, itching, or burning is evident. 3. Ingestion - If Freons are ingested, do not induce vomiting, as the hazard of aspirating the material into

the lungs is greater than allowing it to progress through the intestinal tract. Drink one to two glasses of warm water and obtain medical attention if necessary. 4. Inhalation - Move the exposed individual to fresh air immediately. If the person is not breathing, give

artificial respiration. If the person has difficulty breathing, give oxygen. Seek medical attention.

Safe handling Best practices for the safe handling of refrigerants include: 1. Store refrigerants in a clean, dry area out of direct sunlight, where temperature that does not exceed

50°C;

2. Never pressurise refrigerant systems or vessels with air for leak testing or any other purpose; 3. Never tamper with cylinder valves or pressure relief devices; 4. Never reuse or recharge disposable cylinders; 5. Wear protective clothing such as gloves and eye protection when handling any refrigerant; 6. Avoid contact with liquid refrigerant because frostbite may occur; 7. Avoid exposure to vapours through spills or leaks; 8. Evacuate the area if a large spill occurs. Return only after the area has been properly ventilated; 9. Verify proper cylinder hookup to the system; 10. Check to be sure the cylinder label matches the colour code; 11. Open cylinder valves slowly; 12. Avoid rough handling of refrigerant cylinders; 13. Do not perform any repair on pressurised equipment. Verify that the system has been completely evacuated with a vacuum pump before opening any lines; 14. Before welding or brazing, evacuate the equipment and then break the vacuum with air or nitrogen; 15. Always ventilate the work area before using open flames

The following precautions are recommended for the safe handling of used refrigerant:

Use personal protective equipment, such as side shield glasses, gloves, safety shoes and hard hat, when filling and handling cylinders. Avoid skin contact with liquid refrigerant since it may cause frostbite. Be aware that inhalation of high concentrations of refrigerant vapor is harmful and may cause heart irregularities, unconsciousness or death. Since vapor is heavier than air. avoid low areas without suitable ventilation. Do not apply open flame or heat cylinder above 125° F (52° C). Do not artificially cool cylinder. Use only cylinders designed and marked for refrigerant recovery service. DO NOT REUSE cylinders intended for virgin refrigerant service. Make certain the cylinder is charged only with the refrigerant for which it is designated and labeled. DO NOT mix different refrigerants in the same cylinder.

PRE-FILL PROCEDURES

Prior to filling a recovery cylinder, identify the refrigerant to be recovered and make certain the cylinder is marked and labeled for that refrigerant. Read all labels. Make certain the cylinder retest date has not expired. Do not fill if the present date is more than 5 years past the most recent marked test date. Inspect cylinder for signs of damage, such as dents, gouges, corrosion. Do not fill damaged cylinders.

Inspect valve for damage and ease of operation. Determine maximum allowable gross (filled) weight—this should be prominently marked on the side of the cylinder.

FILLING PROCEDURE

Be sure you have an accurate scale suitable for weighing the cylinder and contents, a proper gauge set manifold and proper hoses and connectors. Be sure cylinder is free standing on the scale with no restriction of free movement caused by hoses, connections, etc. Monitor pressure during filling carefully. DO NOT exceed maximum service pressure which is stamped on shoulder or collar of the cylinder. Monitor gross weight during filling to assure that overfilling does not occur. Shut off valve if maximum gross weight or service pressure is reached. DO NOT OVERFILL. After recovery, close cylinder valve securely. Check weigh cylinder.

PRE-SHIPMENT PROCEDURES

Leak check. DO NOT ship a leaking cylinder. Apply outlet cap. Apply steel valve protector cover. Make certain cylinder bears appropriate DOT (TC) label and refrigerant identification/ precautionary labels and markings. Inspect valve for damage and ease of operation. Determine maximum al lowable gross ( filled) weight—this should be prominently marked on the side of the cylinder.

A SAFETY CASE STUDY

On one of the Belgian ships, the second engineer came to the engine control room and found it extremely warm. He went to check on the A/C compressors. Noting a loss of Freon in the system, he decided to check for leaks. Based on his previous experience, he checked the switchboard room first, as similar leaks had occurred there before. On entering the switchboard

room he ‘smelled’ Freon gas and instantly started to feel dizzy. Fortunately,

he managed to turn round and made it out of the room safely. Having left the switchboard room, the engineer had to sit down in order to recover from the dizziness. After this near-miss, the room was entered with breathing apparatus, the source of the Freon leak was found, the system was isolated, the leak repaired and the room thoroughly ventilated. On another vessel, a low level alarm of Freon in the refrigerator compressor was observed in the engine control room. The chief engineer decided to recharge the system, using a flexible hose linking a full Freon cylinder and the recharging valve located on the compressor. After recharging, he closed the supply valve on the cylinder, then closed the valve on the compressor and released the pressure from the hose. After disconnecting the hose, the chief engineer observed that the recharging valve on the compressor was leaking. He decided temporarily to fit a threaded plug over the leaking valve to control the gas before a repair attempt could be made. He momentarily removed the leather glove he was wearing and while threading the plug, a jet of liquid Freon splashed on his left hand, causing severe frost burns. Fortunately the ship was in port, so he was taken for medical treatment ashore.

Root cause/contributory factors 1. Lack of procedures; 2. Inadequate situational awareness; 3. Poor risk assessment; 4. Failure to use personal protective equipment (PPE) properly; 5. Failure of the recharging valve spindle; or 6. Recharging valve not closed properly (due to hard turning of the spindle), which allowed Freon to escape.

Corrective actions SMS procedures reviewed as health and safety hazards of refrigerant gases were not adequately addressed in the manuals.

FREON 22 MATERIAL SAFETY DATA SHEETS

Material Safety Data Sheet ----------------------------------------------------------------------

"FREON" 22

2008FR Revised 11-MAR-2010

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CHEMICAL PRODUCT/COMPANY IDENTIFICATION

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Material Identification

Corporate MSDS Number : DU000025

Formula : CHClF2

Molecular Weight : 86.47

CAS Name : "FREON" 22

Tradenames and Synonyms

Freon 22

CHLORODIFLUOROMETHANE

HCFC-22

CC0335

Dymel 22

Company Identification

MANUFACTURER/DISTRIBUTOR

DuPont Fluoroproducts

1007 Market Street

Wilmington, DE 19898

PHONE NUMBERS

Product Information : 1-800-441-7515 (outside the U.S.

302-774-1000)

Transport Emergency : CHEMTREC 1-800-424-9300(outside U.S.

703-527-3887)

Medical Emergency : 1-800-441-3637 (outside the U.S.

302-774-1000)

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COMPOSITION/INFORMATION ON INGREDIENTS

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Components

Material CAS Number %

*"FREON" 22 METHANE, CHLORODIFLUORO- 75-45-6 100

* Disclosure as a toxic chemical is required under Section 313 of

Title III of the Superfund Amendments and Reauthorization Act of 1986

and 40 CFR part 372.

2008FR DuPont Page 2

Material Safety Data Sheet

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HAZARDS IDENTIFICATION

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Potential Health Effects

Inhalation of high concentrations of vapor is harmful and

may cause heart irregularities, unconsciousness or death.

Intentional misuse or deliberate inhalation can be fatal.

Vapors are heavier than air and pose a threat of suffocation

if trapped in enclosed or low places. Liquid contact can

cause frostbite. Inhalation may cause dizziness, headache,

confusion, incoordination, and loss of consciousness.

Immediate effects of overexposure by inhalation may include

central nervous system depression with dizziness, confusion,

incoordination, drowsiness or unconsciousness. Gross

overexposure may cause irregular heart beat with a strange

sensation in the chest, "heart thumping", apprehension,

lightheadedness, feeling of fainting, dizziness, weakness,

sometimes progressing to loss of consciousness and death.

Other effects include fatality from gross over-exposure.

Short-term overexposure by skin contact may cause frostbite,

if liquid or escaping vapor contacts the skin. Repeated

and/or prolonged exposure may cause defatting of the skin

with itching, redness or rash. Data to evaluate the skin

permeation hazard of this compound are insufficient. There

are no reports of human sensitization.

Contact with the vapor or aerosol may cause eye irritation

with tearing, pain or blurred vision.

Increased susceptibility to the effects of this material may

be observed in persons with pre-existing disease of the

central nervous system, cardiovascular system.

Carcinogenicity Information

None of the components present in this material at concentrations

equal to or greater than 0.1% are listed by IARC, NTP, OSHA or ACGIH

as a carcinogen.

----------------------------------------------------------------------

FIRST AID MEASURES

----------------------------------------------------------------------

First Aid

INHALATION

If inhaled, immediately remove to fresh air. Keep person

calm. If not breathing, give artificial respiration. If

breathing is difficult, give oxygen. Call a physician.

SKIN CONTACT

In case of contact, flush area with lukewarm water. Do not



(FIRST AID MEASURES - Continued)

use hot water. If frostbite has occurred, call a physician.

EYE CONTACT

In case of contact, immediately flush eyes with plenty of

water for at least 15 minutes. Call a physician.

INGESTION

Ingestion is not considered a potential route of exposure.

Notes to Physicians

THIS MATERIAL MAY MAKE THE HEART MORE SUSCEPTIBLE TO

ARRHYTHMIAS. Catecholamines such as adrenaline, and other

compounds having similar effects, should be reserved for

emergencies and then used only with special caution.

----------------------------------------------------------------------

FIRE FIGHTING MEASURES

----------------------------------------------------------------------

Flammable Properties

Flash Point : Will not burn

Autodecomposition : 632 C (1170 F)

Other burning materials may cause "FREON" 22 to burn weakly.

Chlorodifluoromethane is not flammable at ambient

temperatures and atmospheric pressure. However,

chlorodifluoromethane has been shown in tests to be

combustible at pressures as low as 60 psig at ambient

temperature when mixed with air at concentrations of 65

volume % air. Experimental data have also been reported

which indicate combustibility of "FREON" 22 in the presence

of certain concentrations of chlorine.

Fire and Explosion Hazards:

Cylinders may rupture under fire conditions. Decomposition

may occur.

Extinguishing Media

As appropriate for combustibles in area. Extinguishant

for other burning material in area is sufficient to stop

burning.

Fire Fighting Instructions

Use water spray or fog to cool containers. Self-contained

breathing apparatus (SCBA) is required if cylinders rupture

or contents are released under fire conditions. Water

runoff should be contained and neutralized prior to release.



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ACCIDENTAL RELEASE MEASURES

----------------------------------------------------------------------

Safeguards (Personnel)

NOTE: Review FIRE FIGHTING MEASURES and HANDLING (PERSONNEL)

sections before proceeding with clean-up. Use appropriate

PERSONAL PROTECTIVE EQUIPMENT during clean-up.

Accidental Release Measures

Ventilate area, especially low or enclosed places where

heavy vapors might collect. Remove open flames. Use

self-contained breathing apparatus (SCBA) for large spills

or releases.

----------------------------------------------------------------------

HANDLING AND STORAGE

----------------------------------------------------------------------

Handling (Personnel)

Use with sufficient ventilation to keep employee exposure

below recommended limits. "FREON" 22 should not be mixed

with air for leak testing. In general, it should not be

used or allowed to be present with high concentrations of

air above atmospheric pressure. Contact with chlorine or

other strong oxidizing agents should also be avoided.

Storage

Clean, dry area. Do not heat above 52 C (125 F).

----------------------------------------------------------------------

EXPOSURE CONTROLS/PERSONAL PROTECTION

----------------------------------------------------------------------

Engineering Controls

Normal ventilation for standard manufacturing procedures is

generally adequate. Local exhaust should be used when large

amounts are released. Mechanical ventilation should be

used in low or enclosed places.

Personal Protective Equipment

Impervious gloves and chemical splash goggles should be used

when handling liquid. Under normal manufacturing

conditions, no respiratory protection is required when

using this product. Self-contained breathing apparatus

(SCBA) is required if a large release occurs.

Exposure Guidelines



Exposure Limits

"FREON" 22

PEL (OSHA) : None Established

TLV (ACGIH) : 1,000 ppm, 3,540 mg/m3, 8 Hr. TWA, A4

AEL * (DuPont) : None Established

* AEL is DuPont’s Acceptable Exposure Limit. Where governmentally

imposed occupational exposure limits which are lower than the AEL

are in effect, such limits shall take precedence.

----------------------------------------------------------------------

PHYSICAL AND CHEMICAL PROPERTIES

----------------------------------------------------------------------

Physical Data

Boiling Point : -40.8 C (-41.4 F)

Vapor Pressure : 151 psig @ 25 C (77 F)

Vapor Density : 3.03 (Air=1.0) @ 25 C (77 F)

% Volatiles : 100 WT%

Evaporation Rate : >1 (CCl4=1.0)

Solubility in Water : 0.3 WT% @ 25 C (77 F)

pH : Neutral

Odor : Slight ethereal

Form : Liquified Gas.

Color : Clear, Colorless.

Liquid Density : 1.194 g/cm3 @ 25 C (77 F)

----------------------------------------------------------------------

STABILITY AND REACTIVITY

----------------------------------------------------------------------

Chemical Stability

Material is stable. However, avoid open flames and high

temperatures.

Incompatibility with Other Materials

Incompatible with alkali or alkaline earth metals--powdered

Al, Zn, Be, etc.

Decomposition

Decomposition products are hazardous. "FREON" 22 can be

decomposed by high temperatures (open flames, glowing metal

surfaces, etc.) forming hydrochloric and hydrofluoric acids,

and possibly carbonyl halides. These materials are toxic

and irritating. Contact should be avoided.

Polymerization

Polymerization will not occur.



----------------------------------------------------------------------

TOXICOLOGICAL INFORMATION

----------------------------------------------------------------------

# Animal Data

INHALATION:

4 hour, LC50, rat: 220,000 ppm.

Inhalation 4 hour, LC50, rat: 220,000 ppm

Single inhalation exposure to high doses caused central

nervous depression, inactivity or anaesthesia, altered

respiratory rate, and cardiac sensitization (a potentially

fatal disturbance of heart rhythm associated with a

heightened sensitivity to the action of epinephrine).

No data are available on acute oral or dermal toxicity for

this substance.

Animal testing indicates this substance is not an eye

irritant.

Animal testing indicates this substance is not a skin

irritant or skin sensitizer.

Repeated inhalation exposure caused reduced body weight gain

and organ weight effects. In chronic inhalation studies, an

increased incidence of tumors was observed in some

laboratory animals but not in others. The overall weight of

evidence indicates that the substance is not carcinogenic.

Animal testing showed effects on embryo-fetal development at

exposure levels equal to or above those causing maternal

toxicity. This substance is not considered a unique

developmental hazard to the conceptus. Evidence suggests

the substance is not a reproductive toxin in animals.

Experiments showed the substance to cause mutagenic effects

in cultured bacterial cells. The substance did not cause

genetic damage in cultured mammalian cells. Evidence

suggests this substance does not cause genetic damage in

animals.

----------------------------------------------------------------------

ECOLOGICAL INFORMATION

----------------------------------------------------------------------

# Ecotoxicological Information

Aquatic Toxicity:

"FREON" 22

48 hour EC50 - Daphnia magna: 433 mg/L

96 hour LC50, Zebra fish: 777 mg/L



(ECOLOGICAL INFORMATION - Continued)

Biodegradation: according to the results of test of

biodegradability, this substance is not readily

biodegradable.

----------------------------------------------------------------------

DISPOSAL CONSIDERATIONS

----------------------------------------------------------------------

Waste Disposal

Comply with Federal, State, and local regulations. Reclaim

by distillation or remove to a permitted waste disposal

facility.

----------------------------------------------------------------------

TRANSPORTATION INFORMATION

----------------------------------------------------------------------

Shipping Information

DOT/IMO

Proper Shipping Name : CHLORODIFLUOROMETHANE

Hazard Class : 2.2

UN No. : 1018

DOT/IMO Label : NONFLAMMABLE GAS

Shipping Containers

Tank Cars.

Tank Trucks.

Cylinders.

----------------------------------------------------------------------

REGULATORY INFORMATION

----------------------------------------------------------------------

U.S. Federal Regulations

TSCA Inventory Status : Reported/Included.

TITLE III HAZARD CLASSIFICATIONS SECTIONS 311, 312

Acute : Yes

Chronic : No

Fire : No

Reactivity : No

Pressure : Yes

HAZARDOUS CHEMICAL LISTS

SARA Extremely Hazardous Substance: No

CERCLA Hazardous Substance : No

SARA Toxic Chemical - See Components Section



----------------------------------------------------------------------

OTHER INFORMATION

----------------------------------------------------------------------

NFPA, NPCA-HMIS

NPCA-HMIS Rating

Health : 1

Flammability : 0

Reactivity : 1

Personal Protection rating to be supplied by user depending on use

conditions.

----------------------------------------------------------------------

The data in this Material Safety Data Sheet relates only to the

specific material designated herein and does not relate to use in

combination with any other material or in any process.

Responsibility for MSDS : MSDS Coordinator

> : DuPont Fluoroproducts

Address : Wilmington, DE 19898

Telephone : (800) 441-7515

# Indicates updated section.

This information is based upon technical information believed to be

reliable. It is subject to revision as additional knowledge and

experience is gained.

THE FUTURE OF REFRIGERATION

Future of refrigeration

In 1973, Prof. James Lovelock reported finding trace amounts of refrigerant gases in the atmosphere. In 1974, Sherwood Rowland and Mario Molina predicted that chlorofluorocarbon (CFC's) refrigerant gases would reach the high stratosphere and there damage the protective mantle of the oxygen allotrope, ozone. In 1985 the "ozone hole" over the Antarctic had been discovered and by 1990 Rowland and Molina's prediction was proved correct.

As a result of the potential ozone layer damage. new technologies in refrigerants have been developed. The most popular are known as hydrofluorocarbons (HFCs), with an even lower global warming potential, and no known effects at all on the ozone layer.

The future of refrigeration at the beginning of the 21st Century is now very driven by conservation and has many different demands placed on it.

Not only do modern refrigeration systems have to be built in an environmentally friendly way, they have to run as efficiently as possible with low energy consumption. The gas or chemical inside the appliance also has to be safe and have low impact on the environment if released.

So a clean and green method of refrigeration is the future and we will look into the different ideas and progress thus far.

MAGENTIC REFRIGERATION

Karl Sandeman, a physicist at Cambridge University, UK, has helped resolve the practical issues, the cooling power of the 21st century fridge will come from a 19th century discovery - and it promises to cut energy consumption by 40% and save the ozone layer.

The key is a material that cools when it is put in a magnetic field. The idea - which is ambitious, but feasible - is to replace the present system used by refrigerators the world over. Your kitchen fridge has a compressor, which turns a gas into a liquid, releasing heat (which you'll feel at the back of the fridge). The liquid is then pumped round the inside walls of the fridge, where it draws heat from the contents; that turns it into a gas, which is pumped on to the compressor.

But what if you could replace the fluid with a magnet? "The amazing thing about magnetism is that it's actually a quantum mechanical phenomenon," says Sandeman. "It's all down to something mysterious called spin. The electrons act almost like a miniature bar magnet."

Temperature change

As a quantum mechanical property of the electron, spin is usually taken to mean its rotational momentum (like the Earth rotating around its axis). That momentum - described as "up" or "down" - creates a tiny magnetic field. When all the electrons in a material spin in the same way, their fields combine to create what we perceive as

magnetism. However, an iron magnet heated to 700C will "disorder" and lose its powers, known as a magnetic phase transition.

In 1881, the German physicist Emil Warburg put a block of iron into a strong magnetic field and found it increased very slightly in temperature. Scientists now know the electrons pivot in the field to align at a lower energy state, releasing surplus energy. The metal warms up in what's known as the magnetocaloric effect, which is greatest near the magnetic phase transition temperature.

"If you can suddenly alter the degree of ordering of all these little spins, then you get a large response," says Sandeman. For iron at room temperature, the response is just 0.1C. Some materials cool in a magnetic field, a property that's used in low temperature research. Finding the right room temperature material is the key to a magnetic fridge, where the cooling power is derived from a positive magnetocaloric effect coupled to heat exchange.

One material works nicely: the element gadolinium (Gd). It's a silvery-white metal that's strongly attracted by a magnet, has a magnetic disordering temperature of 20C, and a giant magnetocaloric effect of several degrees. A waste product from permanent magnet manufacture, gadolinium costs around £100 per kg; a magnetic fridge would use 0.15kg. Sandeman's current research, however, is looking at other possibilities.

"The quest is to get away from these expensive rare earth materials and look for magnetic materials which have a phase transition at room temperature," says Sandeman, whose research job at Cambridge University is funded by the Royal Society. He also works with Professor Derek Fray, a leading expert in materials chemistry. "What I'm actually working with is an alloy of two magnetic materials, cobalt and manganese," says Sandeman.

When these elements are mixed with non-magnetic "spacers" like silicon, the cost falls to £5 per kg. Strangely, his latest experimental alloy has a negative magnetocaloric effect - it cools in a magnetic field. This could also be harnessed for fridges through a heat exchange process.

A Cambridge University spin-out company, Camfridge Ltd, has built two prototype magnetic fridges that use gadolinium. While the latest one is little more than fridge innards, the team - which includes Sandeman as chief scientific officer, Fray and experienced business people - is striving to develop the revolutionary effect for commercial exploitation in fridges and, perhaps, air conditioning.

"It's a sea change in thinking," says Sandeman. "It never ceases to amaze me how you can take a block of this stuff and stick it into a [magnetic] field. The prototype is operational and has achieved a large temperature span."

A magnetic fridge works like this. Powdered gadolinium (with coarse grains for good heat transfer qualities) is put into a magnetic field. It heats up as the randomly ordered magnetic moments - the electrons with spin - are aligned, or "ordered", by the field. The newly-acquired heat - a boost of between 2-5C, depending on the gadolinium's original temperature - is removed by a circulating fluid, like a conventional fridge.

The magnetic field is removed and the gadolinium cools below its starting temperature as the electrons resume their previously disordered state. Heat from the system to be cooled - your fridge interior - can then be transferred to the now cooler metal. Then all you do is endlessly repeat. But unlike conventional fridges, which need very toxic chemicals, the only liquid needed for heat transfer is water, alcohol or, more likely, antifreeze.

A more advanced prototype next year will optimally bring together three elements - temperature span, cooling power and efficiency - along with a faster motor. This will allow less gadolinium to be used with a smaller magnet, saving materials costs. Camfridge's managing director, Neil Wilson, says: "In terms of technical specification, that prototype will get us to a domestic fridge. Commercial manufacturers have hit the wall; there is not much more they can do. We're wanting to cut the energy use by half."

Professor Stephen Blundell, of Oxford University, also understands the issues well, as he's written a textbook on magnetism and researches magnetic properties in materials. Magnetocaloric effects are becoming more practical, he thinks, thanks to improved magnet technology and new materials. A magnetic fridge would be compact, less noisy and won't need harmful gases.

"I think this technology has real potential, but it is still at the early stages. The claims of 40% efficiency savings seem a little speculative, though not completely unreasonable," says Blundell.

Some 15% of UK energy is used in refrigeration and cooling for air conditioning, and much more in warmer countries. Garry Staunton, head of low carbon research at the Carbon Trust, which is financially supporting the magnetic fridge's development along with Cambridge University and other investors, says that 22m tonnes of UK carbon dioxide emissions annually are due to refrigeration and air conditioning. Efficiency improvements to domestic fridges since 1990 have seen a 27% reduction in their energy use.

Increasing energy efficiency with new technology is the key to stabilising and reducing carbon emissions. Consumers seem willing to support and demand new energy-efficient appliances in their homes, while everyone has felt the sharply rising cost of electricity. As the fridge magnet moves inside the fridge, it may become the exciting new green technology of the 21st century.

CARBON D IOXIDE REFRIGERATION

Researchers are making progress in perfecting automotive and portable air-conditioning systems that use environmentally friendly carbon dioxide as a refrigerant instead of conventional, synthetic global-warming and ozone-depleting chemicals. Engineers will discuss their most recent findings from July 25 to 28, during the Gustav Lorentzen Conference on Natural Working Fluids, one of three international air-conditioning and refrigeration conferences to be held concurrently at Purdue University. Unlike the two other conferences, the biannual Gustav Lorentzen Conference, which is being held for the first time in the United States, focuses on natural refrigerants that are thought to be less harmful to the environment than synthetic chemical compounds.

"The Gustav Lorentzen Conference focuses on substances like carbon dioxide, ammonia, hydrocarbons, air and water, which are all naturally occurring in the biosphere," says James Braun, an associate professor of mechanical engineering at Purdue who heads the organizing committee for all three conferences. "Most of the existing refrigerants are manmade."

Purdue engineers will present several papers detailing new findings about carbon dioxide as a refrigerant, including:

Creation of the first computer model that accurately simulates the performance of carbon-dioxide-based air conditioners. The model could be used by engineers to design air conditioners that use carbon dioxide as a refrigerant. A paper about the model will be presented on July 26 during a special session sponsored by the U.S. Army in which researchers from several universities will present new findings.

The design of a portable carbon-dioxide-based air conditioner that works as well as conventional military "environmental control units." Thousands of the units, which now use environmentally harmful refrigerants, are currently in operation. The carbon dioxide unit was designed using the new computer model. A prototype has been built by Purdue engineers and is being tested.

The development of a mathematical "correlation," a tool that will enable engineers to design heat exchangers the radiator-like devices that release heat to the environment after it has been absorbed during cooling for future carbon dioxide-based systems. The mathematical correlation developed at Purdue, which will be published in a popular engineering handbook, enables engineers to determine how large a heat exchanger needs to be to provide cooling for a given area.

The development of a new method enabling engineers to predict the effects of lubricating oils on the changing pressure inside carbon dioxide-based air conditioners. Understanding the drop in pressure caused by the oil, which mixes with the refrigerant and lubricates the compressor, is vital to predicting how well an air conditioner will perform.

Although carbon dioxide is a global-warming gas, conventional refrigerants called hydrofluorocarbons cause about 1,400 times more global warming than the same quantity of carbon dioxide. Meanwhile, the tiny quantities of carbon dioxide that would be released from air conditioners would be insignificant, compared to the huge amounts produced from burning fossil fuels for energy and transportation, says Eckhard Groll, an associate professor of mechanical engineering at Purdue.

Carbon dioxide is promising for systems that must be small and light-weight, such as automotive or portable air conditioners. Various factors, including the high operating pressure required for carbon-dioxide systems, enable the refrigerant to flow through small-diameter tubing, which allows engineers to design more compact air conditioners.

More stringent environmental regulations now require that refrigerants removed during the maintenance and repair of air conditioners be captured with special equipment, instead of being released into the atmosphere as they have been in the past. The new "recovery" equipment is expensive and will require more training to operate, important

considerations for the U.S. Army and Air Force, which together use about 40,000 portable field air conditioners. The units, which could be likened to large residential window-unit air conditioners, are hauled into the field for a variety of purposes, such as cooling troops and electronic equipment.

"For every unit they buy, they will need to buy a recovery unit," Groll says. "That's a significant cost because the recovery unit is almost as expensive as the original unit. Another problem is training. It can be done, but it's much more difficult than using carbon dioxide, where you could just open a valve and release it to the atmosphere."

The recovery requirement would not apply to refrigerants made from natural gases, such as carbon dioxide, because they are environmentally benign, says Groll, who estimates that carbon dioxide systems probably will take another five to 10 years to perfect.

Carbon dioxide was the refrigerant of choice a century ago, but it was later replaced by synthetic chemicals.

"It was actually very heavily used as a refrigerant in human-occupied spaces, such as theaters and restaurants, and it did a great job," says Groll, who is chair of the Gustav Lorentzen Conference.

But one drawback to carbon dioxide systems is that they must be operated at high pressures, up to five times as high as commonly seen in current technology. The need to operate at high pressure posed certain engineering challenges and required the use of heavy steel tubing.

During the 1930s, carbon dioxide was replaced by synthetic refrigerants, called chlorofluorocarbons, or CFCs, which worked well in low-pressure systems. But scientists later discovered that those refrigerants were damaging the Earth's stratospheric ozone layer, which filters dangerous ultraviolet radiation. CFCs have since been replaced by hydrofluorocarbons, which are not hazardous to the ozone layer but still cause global warming.

However, recent advances in manufacturing and other technologies are making carbon dioxide practical again. Extremely thin yet strong aluminum tubing can now be manufactured, replacing the heavy steel tubing.

Carbon dioxide offers no advantages for large air conditioners, which do not have space restrictions and can use wide-diameter tubes capable of carrying enough of the conventional refrigerants to provide proper cooling capacity. But another natural refrigerant, ammonia, is being considered for commercial refrigeration applications, such as grocery store display cases, Groll says.

Engineering those systems is complicated by the fact that ammonia is toxic, requiring a more elaborate design in which the ammonia refrigerant is isolated from human-occupied spaces. The first ammonia systems are currently being tested in Europe, and results will be presented during the Gustav Lorentzen Conference, Groll says.

Groll's work is funded by the U.S. Army, Air Force and the American Society of Heating, Refrigerating and Air-Conditioning Engineers, as well as the Air Conditioning and Refrigeration Technology Institute

SOLAR POW ER

A network of steel pipes and tanks tucked behind a small building at the University of Florida could lead to a new method of creating two seemingly unrelated products -- electricity and refrigeration -- by tapping into the power of the sun. The pipes and tanks are the guts of a just-launched experiment to test what Yogi Goswami, a UF professor of mechanical engineering, describes as a novel solar- or geothermal-powered thermodynamic cycle.

The system, first des"We’ve seen that it works in theory, and we’ve set up this experimental system to prove that it works in practice," said Goswami, a specialist in solar energy who also is director of UF’s Solar Energy & Energy Conversion Laboratory.

Described in the Journal of Solar Energy Engineering last year, will attempt to verify what Goswami describes as a new combination of two classic thermodynamic cycles: the Rankine, or steam cycle, and the absorption-refrigeration cycle.

Both cycles are standard fare in engineering textbooks. The Rankine cycle, typically found in large power plants, uses heat to boil water and create pressurized steam, spinning a turbine and producing electricity. The absorption-refrigeration cycle, seen in large commercial refrigeration units, chills air through boiling and condensing ammonia.

In Goswami’s experimental set-up, hot water is used to heat pressurized ammonia past its boiling point, generating ammonia steam. This is possible because ammonia maintained at the pressure required to spin the turbine boils at a far lower temperature, around 212 degrees Farenheit, than water in the same circumstances, which requires temperatures of at 400 to 500 degrees. In theory, the hot water would come from deep underground or solar collectors, although for the purposes of the experiment a household hot-water heater is used.

The next step is for the pressurized ammonia vapor to spin a turbine and produce electricity (a process simulated in the experiment through using a heat exchanger and expansion valve). The unique part is what happens next. As the ammonia spins the turbine, it actually falls below room temperature, reaching lows of 32 degrees or lower -- cold enough to make ice. The result can be used for refrigeration or air conditioning.

"The unique thing we’re doing is that we can remove so much of the energy from the ammonia in the turbine that it actually becomes very cold," Goswami said. "We can then use that cold gas to our advantage for air conditioning or to create ice."

The system is not the first to attempt to use solar or geothermal power to drive a turbine, Goswami said. The Solar Energy Generating System, a mammoth facility in the Mojave desert in Southern California, has used specially designed hot water collectors to produce as much as 354 megawatts of power -- enough for 70,000 homes. But the

collectors are extremely expensive, making the power more costly than electricity produced with fossil fuel technology.

"The problem has been that the capital cost is about $3,500 per kilowatt of capacity," he said. "To make it competitive, we really need to bring that cost to less than $2,000."

Goswami said his system is more economical because it can use off-the-shelf collectors. Although it could be used on a large scale, the system would be ideal for homes that could easily take advantage of both the electricity and the refrigeration, he said.

"What we’re looking at is we can have a power plant to give you as low as five kilowatts, so a power plant is good enough for a household," he said.

Another application for the technology is to milk additional energy from the hot waste water produced by conventional power plants. Even the most efficient power plants today capture only 30 to 40 percent of the energy in the fuel, releasing the bulk of the remainder in the form of heat -- much of it as hot water with sometimes damaging environmental consequences. Goswami said his system, installed on the outlet pipes for the hot water, could leach 20 to 30 percent more energy from the system while also cooling down the water. As a result, the plant could generate extra electricity while gaining cooling capability for on-site refrigeration or air conditioning needs, he said.

The research is funded with a $175,000 grant from the U.S. Department of Energy, which is interested in developing the geothermal application of the technology.

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what you should know about refrigerant safety - quick reference handout

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