INTRODUCTION

Worldwide concerns about the ozone layer and globalwarming have led to the use of flammable refrigerants.With the introduction of flammable refrigerants, youwill need to make some changes in the way youservice all systems. This document containsprecautions and procedures for servicing flammableand nonflammable refrigerant systems. Figure 1shows the symbol for flammable refrigerants.

NEW PRECAUTIONS FOR ALL SYSTEMS

With the introduction of flammable refrigerants,service technicians should observe the followingprecautions when servicing both flammable andnonflammable refrigerant systems.

Warning: Improper servicing of air conditioning andrefrigeration equipment can lead to serious injury ordeath from fire, electric shock, or explosion.

Use a combustible gas monitor

It is recommended that you always turn on acombustible gas monitor before entering any servicearea to alert you to the presence of flammablerefrigerants while you are working. Figure 2 shows anexample of a flammable refrigerant monitor. Do notunplug, disconnect power to, or begin servicing asystem before checking for flammable refrigerantswith a combustible gas monitor. Do not turn themonitor off until you leave the service area or untilyou determine that the system does not use aflammable refrigerant.

Use a combustible gas monitor that meets CSA C22.2or ANSI/ISA 12.13.01 standards and is designed to

detect propane (R-290) and isobutane (R-600a). Toreduce the risk of fire or explosion, always follow themonitor manufacturer’s instructions. A monitor thatemits an audible signal as opposed to a visual signalis recommended.

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WORKING WITH FLAMMABLE REFRIGERANT SYSTEMS

Excerpted and adapted from the Tecumseh Hermetic Compressor Service Handbook and theTecumseh Hermetic Compressor Service Handbook Supplement. Reprinted with permission.

© 2006 by the Refrigeration Service Engineers Society, Des Plaines, ILSupplement to the Refrigeration Service Engineers Society.

Service Application ManualSAM Chapter 620-116

Section 3

Figure 1. Flammable refrigerant symbol

Figure 2. Typical flammable refrigerant monitor

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Check the system to see if it uses a flammablerefrigerant

Before servicing any system, you should check thecompressor and system labeling to determine if thesystem you are servicing contains a flammablerefrigerant. A compressor designed for use withflammable refrigerants should have the refrigerantdesignation “R-290” or “R-600a” printed on thecompressor serial label, and may also display aseparate flammable refrigerant label. Figures 3 and 4 show examples of these labels.

Never use unauthorized flammable refrigerants

Most manufacturers only authorize the use of thecompressor serial label refrigerant. Any refrigerantnot listed on the compressor serial label is notauthorized by the manufacturer for use in thecompressor and is an “unauthorizedrefrigerant.” Operating or servicing a systemthat contains an unauthorized flammablerefrigerant can lead to risk of fire, excess systempressure, damage to the compressor, or anexplosion.

Use of a refrigerant other than the refrigerantlisted on the compressor serial label may alsovoid the compressor warranty. In addition, theUnited States Environmental Protection Agency(EPA) has declared that it is illegal to replaceCFC-12 (R-12) with any flammable refrigerant,including refrigerants such as Duracool 12a or HC-12®, which claim to be “drop-inreplacements.” The EPA defines theserefrigerants as “unacceptable substituterefrigerants.” According to the EPA,“a service technician who charges a system

with an unacceptable refrigerant may be subject to a $25,000 fine and up to five years jail time.”*

Be aware of unauthorized flammablerefrigerants and unauthorized system retrofits

You may find that some systems have been chargedwith unauthorized flammable refrigerants. To checkfor the use of unauthorized flammable refrigerants,look at the refrigerants listed on all of the system

labels. If a flammable refrigerant is listed on any of the system labels, check that it matches thecompressor serial label refrigerant. If the refrigerantsdo not match, assume that the system may contain anunauthorized flammable refrigerant.

If the system has been retrofitted with flammablerefrigerant or has been charged with an unauthorizedflammable refrigerant, you should always do thefollowing:

1. Stop all service activities and contact the owner.Inform the owner that the system has previouslybeen improperly serviced.

2. Refuse to service the system or appliance.

3. Offer to replace the entire system or appliance.

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*www.epa.gov/ozone/snap/refrigerant/buying.html

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Figure 3. Compressor with serial label (1), flammablerefrigerant label (2), and warning label (3)

Figure 4. Flammable refrigerant serial labels withrefrigerant codes R-600a and R-290

If the owner does not want toreplace the system or appliance,the owner may wish to contactthe technician who changed therefrigerant to correct theproblem. In any event, it isrecommended that you do nofurther work on the system.Operating or servicing a systemthat contains an unauthorizedflammable refrigerant can leadto risk of fire, excess systempressure, damage to thecompressor, or an explosion.

To protect yourself, bystanders, and people whoservice or use the system in the future, never service,repair, or troubleshoot a system unless:

þ you are an air conditioning/refrigerationtechnician;

þ you are familiar with the safety precautions forflammable refrigerants as outlined in thisdocument;

þ you are familiar with the information provided byother sources, such as the manufacturers of thesystem equipment, component manufacturers, andrefrigerant suppliers.

BE PREPARED TO SERVICE FLAMMABLEREFRIGERANT SYSTEMS

It is highly recommended that service techniciansavoid working on air conditioning and refrigerationsystems using flammable refrigerants unless theyhave special training and proper equipment forflammable refrigerants. Improper servicing of airconditioning and refrigerant equipment can lead toserious injury or death from fire, electric shock, orexplosion.

FIRE HAZARD FROM SUDDEN RELEASE OFFLAMMABLE REFRIGERANT

If flammable refrigerant is suddenly released, youshould assume that there will be a flammable

concentration in the area for some time. Dependingon the situation, a sudden release of refrigerant canlead to a flash fire, a sustained fire, or even anexplosion.

FIRE HAZARD FROM TERMINAL VENTING

What is terminal venting?

Oil and refrigerant can spray out of the compressor if one of the terminal pins is ejected from thehermetic terminal block. Figure 5 shows a close-upof a hermetic terminal before and after venting.

This “terminal venting” can occur as a result of aground fault in the compressor (also known as a“short circuit to ground” in the windings of thecompressor motor or in the terminal block itself). The oil and refrigerant spray from terminal ventingcan be ignited by electricity and produce flames thatcan lead to serious burns or death. When spray fromterminal venting is ignited, it is called “terminalventing with ignition.”

Terminal venting and electrocution

Improperly servicing, repairing, or troubleshooting a compressor can lead to terminal venting withignition. To reduce the risk of electrocution, seriousburns, or death from terminal venting with ignition,always follow the precautions listed below:

þ Disconnect all electric power before removing the protective terminal cover. Make sure that all

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Missingterminal pin

Figure 5. Hermetic terminal showing individual terminal pins before venting (left) and after (right)

power legs are open (see Figure 6). Note: Thesystem may have more than one power supplysource.

þ Never energize the system unless: 1) theprotective terminal cover is securely fastened,and 2) the compressor is properly connected toground. Figure 7 below illustrates some of thevarious methods of securing protective terminalcovers.

þ Never reset a circuit breaker or replace a fusewithout first checking for a ground fault (a short

circuit to ground). An open fuse or a trippedcircuit breaker is a strong indication of a groundfault.

þ Be alert for sounds of arcing (sizzling, sputtering,or popping) inside the compressor. Get awayimmediately if you hear these sounds.

þ Always disconnect power from the unit beforeservicing, unless it is required for a specifictroubleshooting technique. In these situations, use extreme caution to avoid serious injury ordeath from electric shock and/or the creation ofelectrical sparks or arcs.

The role of the protective terminal cover

When non-flammable refrigerants are used, fires dueto terminal venting with ignition can be prevented bysecurely fastening the protective terminal cover tothe compressor.

In contrast, if terminal venting occurs in a flammablerefrigerant compressor, it is expected to result in fire(terminal venting with ignition), even if the protectiveterminal cover is securely fastened. However, securelyfastening the protective terminal cover on flammablerefrigerant compressors will reduce the risk ofpersonal injury and property damage from the

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Figure 6. Disconnect all sources of electric powerbefore removing protective terminal cover

Compressor with snap-inprotective terminal cover (1)

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Compressor with protectiveterminal cover (1) held in place

by metal bale strap (2)

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2

Compressor with protectiveterminal cover (1) held

in place by nut (2)

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Figure 7. Common methods of securing protective terminal covers

resulting fire. It also reduces the risk of seriousinjury or death from electric shock.

As with compressors that use non-flammablerefrigerants, compressors using flammablerefrigerants should never be energized unless theprotective terminal cover is securely fastened.

FLAMMABLE REFRIGERANT Q & A

Flammable refrigerant detection

Q: Can I use my sense of smell or sight to detect thepresence of flammable refrigerants?

A: No. You cannot see or smell flammablerefrigerants. Unlike the propane or butane used infurnaces and other fossil fuel appliances, flammablerefrigerants used in refrigeration equipment do notcontain an odorant. Propane and isobutane arenaturally colorless and odorless gases. Never rely onyour sense of smell or sight to detect the presence ofa flammable refrigerant. If you could see flammablerefrigerant vapors, you would see that they tend tomove downward because they are heavier than air(see Figure 8).

Q: How do I detect the presence of flammablerefrigerants?

A: You need two kinds of detectors:

þ To alert you to the presence of a flammablerefrigerant while you are in the service area, use acombustible gas monitor (look back at Figure 2).

þ To locate a flammable refrigerant leak, use aflammable refrigerant leak detector.

Q: Are there standards that my combustible gasmonitor should meet?

A: Yes. It is recommended that you use only amonitor that meets standards CSA C22.2 orANSI/ISA 12.13.01.

Q: Can I use my sense of smell or sight in place of acombustible gas monitor?

A: No.

Q: Will I be able to smell something when I open thesystem?

A: Maybe. Even though the refrigerant is odorless,you may be able to detect a faint odor from therefrigerant mixed with oil and/or contaminants.However, you must never expect to rely on your sense of smell to detect the presence of a flammablerefrigerant.

Q: Are there some flammable refrigerants that I cansmell?

A: Yes. Some unauthorized flammable refrigerantsmay contain an odorant.

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Figure 8. Flammable refrigerant vapors areheavier than air

Flammable refrigerant specifications

Q: What flammable refrigerants are authorized foruse by most compressor manufacturers?

A: R-290 (propane) and R-600a (isobutane) are theonly flammable refrigerants currently authorized bymost manufacturers for use in their compressors.

Q: How are flammable refrigerant canisters labeled?

A: A canister that contains flammable refrigerant is identified with the refrigerant designation (eitherR-290 or R-600a) and with a “flammable” warninglabel (see Figure 9).

Q: How can compressors designed for use withflammable refrigerants be identified?

A: There are generally two labels that identify aflammable refrigerant compressor: 1) the serial labelcontaining the refrigerant code, and 2) a separateflammable refrigerant label (see Figures 3 and 4).

Q: Are there flammable refrigerants that may not beused in compressors?

A: Yes. Most manufacturers only authorize the use ofR-290 and R-600a if these refrigerant codes appearon the compressor serial label (see Figure 4). Mostmanufacturers do not authorize the use of any

flammable refrigerants other than R-290 and R-600a.Some refrigerants sold as substitutes or “drop-in”replacements for non-flammable refrigerants are, infact, flammable. Most manufacturers forbid the use of these refrigerants in their compressors.

Q: Are flammable refrigerants heaver than air?

A: Yes (see Figure 8).

Q: Generally, how can flammable refrigerants beignited?

A: The three elements needed to start and sustain a fire are air (oxygen), fuel, and an ignition source(see Figure 10). If a flammable refrigerant mixes with air in the right concentration, it can be ignited.Depending on the situation, this can lead to a flashfire, a sustained fire, or even an explosion.

Q: What can ignite flammable refrigerants?

A: In general, things that might ignite flammablerefrigerants include electrical sparks/arcs, flames,static electricity, and hot surfaces that are beginningto glow red (>1,200°F). Some sources of ignitioninclude the following:

þ heating elements of heat guns;

þ halide torches;

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Ignition source

OxygenFuel

Figure 9. Example of label on R-600a canister Figure 10. Diagram of “fire triangle”

þ electronic leak detectors that are not designed todetect flammable refrigerants;

þ vacuum pumps;

þ recovery machines;

þ unplugging appliances or disconnecting power;

þ any event that will cause an electric spark or arc.

Flammable refrigerant precautions

Q: What happens if there is a sudden release offlammable refrigerant?

A: If refrigerant suddenly escapes the system (forexample, if a refrigerant line breaks), you shouldassume that there will be a flammable concentrationin the area for some time.

Q: Are there some tools or procedures that I shouldnot use to service a flammable refrigerant system?

A: Yes. In general, you should not use a tool orprocedure that can ignite flammable refrigerants ifthere is an alternative that will not. For example, donot use heat guns, halide torches, or electronic leakdetectors that are not designed to detect flammablerefrigerants (see Figure 11).

Q: How should I determine if tools or devices areappropriate for use in servicing flammable refrigerantsystems?

A: Consult the tool or device manufacturer.

Q: Will I need to use a tool or device that may be asource of ignition?

A: Maybe. For example, currently available vacuumpumps and recovery machines have motors andswitches that may spark. When non-sparking toolsand devices become available, you should obtain anduse them.

Q: Why do flammable refrigerant compressors usepositive temperature coefficient (“PTC”) start relays?

A: PTC-type start relays do not spark, thus reducingthe risk of a fire in case of a sudden release offlammable refrigerant during operation. Do notreplace a PTC-type start relay with any other startdevice. In contrast, current and potential-type relaysor start capacitors do spark during operation, andshould never be used in a flammable refrigerantsystem.

GENERAL PRECAUTIONS: MONITOR, VENTILATE,ELIMINATE

Never unplug, disconnect power to, or beginservicing a system before checking for flammablerefrigerants with a combustible gas monitor. Prior toservicing, always follow these three steps:

1. Monitor

Always turn on a combustible gas monitor beforeentering any service area to alert you to the presenceof a flammable refrigerant while you are working. Do not unplug, disconnect power to, or beginservicing a system before checking for flammablerefrigerants with a combustible gas monitor. Do notturn the monitor off until you are ready to leave theservice area.

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Figure 11. Do not use tools like heat guns thatcan ignite flammable refrigerants

Use a monitor that meets standards CSA C22.2 orANSI/ISA 12.13.01 and that is designed to detectpropane and isobutane. To reduce the risk of fire orexplosion, always follow the combustible gas monitormanufacturer’s operating instructions. A monitor thatemits an audible signal as opposed to a visual signalis recommended.

2. Ventilate

Establish and maintain good ventilation of theservice area.

3. Eliminate

Extinguish sources of ignition in the service areaprior to beginning service work. For example, turnoff the gas and/or disconnect electric power to allappliances.

Be aware of tools and procedures that may causesparks when servicing. Do not use any tools orprocedures that unnecessarily create sources ofignition.

Remember: monitor, ventilate, eliminate!

REFRIGERANTS AND OTHER CHEMICALS

Direct contact with refrigerant, mixtures of refrigerantand oil, or other chemicals can cause a variety ofinjuries, including burns and frostbite. For example,if refrigerant comes in contact with the skin or eyes,it can cause severe frostbite. Also, in the event of acompressor motor failure, some refrigerant and oilmixtures can be sufficiently acidic to cause chemicalburns.

To avoid injury, always wear appropriate protectiveeye-wear, gloves, and clothing when servicing an airconditioning or refrigeration system. Refer to yourrefrigerant supplier for more information aboutpersonal protective equipment.

If refrigerant or mixtures of refrigerant and oil comein contact with the skin or eyes, flush the exposedarea with water and seek medical attentionimmediately.

COMPRESSOR CHANGE-OUT

Compressor removal

Failure to remove the compressor properly can resultin serious injury or death from electrocution, fire, orthe sudden release of refrigerant and oil.

Before removing a compressor from a system, followthese precautions:

1. Disconnect all electric power. Disconnect allelectric power supplies to the system, makingsure that all power legs are open. (Note: Be awarethat some systems may have more than one powersupply.)

2. Attach gauges to both the high and low sides ofthe system.

3. To avoid the release of refrigerant and oil, be surethat the refrigerant is recovered from the systembefore removing the compressor. Always recoverfrom the both the high and low sides of the systemin order to make sure that refrigerant is nottrapped by a restriction in the system. Attemptingto remove the compressor before recovering allrefrigerant from the system can cause a suddenrelease of refrigerant and oil. Among other things,this can:

þ cause a variety of injuries, including burnsand frostbite;

þ cause a fire if a torch is used to disconnect thetubing;

þ expose the service technician to toxic gases.

Remember: To avoid serious injury or death, be sure to remove and recover all refrigerant beforeattempting the remove the compressor.

4. Whenever possible, use a tubing cutter rather thana torch to remove the compressor (see Figure 12).If you must use a torch to remove the compressor,do so while running dry nitrogen through thesystem.

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Compressor installation

When installing the compressor, do not makeconnections by soft soldering. Assume that a softsolder connection will eventually fail and may cause a sudden release of refrigerant. The only acceptablemethods for soldering are brazing and silversoldering.

Sealing the process tube

Seal the process tube by pinching the end andsealing it with brazing material or silver solder, asshown in Figure 13. Improperly sealing the processtube may lead to leaks or a sudden release offlammable refrigerant.

SYSTEM FLUSHING, PURGING, AND PRESSURE-TESTING FOR LEAKS

Failure to properly flush, purge, or pressure-test asystem for leaks can result in serious injury or deathfrom explosion, fire, or contact with acid-saturatedrefrigerant or oil mists.

Observe the following precautions when flushingand/or purging a system or pressure-testing a systemfor leaks:

þ Always use flushing products according to themanufacturer’s instructions.

þ To purge a system, use only dry nitrogen.

þ When pressure-testing for leaks, use only regulateddry nitrogen or a dry nitrogen plus trace amountsof the serial label refrigerant.

þ When purging or pressure-testing any refrigerationor air conditioning system for leaks, never use air,oxygen, or acetylene. Oxygen can explode oncontact with oil. Acetylene can decompose andexplode when exposed to pressures greater thanapproximately 15 psig. Combining an oxidizinggas, such as oxygen or air, with an HCFC or HFCrefrigerant under pressure can result in a fire orexplosion.

þ Use a pressure-regulating valve and pressuregauges. Commercial cylinders of nitrogen contain pressures in excess of 2,000 psig at 70°F. At pressures much lower than 2,000 psig,compressor can explode and cause serious injuryor death. To avoid overpressurizing the system,always use a pressure-regulating valve on thenitrogen cylinder discharge outlet (see Figure 14on the next page). The pressure regulator must beable to reduce the pressure down to 1 or 2 psig

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Unsealed

Sealed

Figure 12. Use tubing cutter rather than torch toremove compressor

Figure 13. Unsealed and sealed compressorprocess tubes

and maintain this pressure. The regulating valvemust be equipped with two pressure gauges—onegauge to measure the cylinder pressure, and onegauge to measure the discharge or downstreampressure.

þ Use a pressure relief valve. In addition to apressure-regulating valve and gauges, alwaysinstall a pressure relief valve. This can also be a frangible disk-type pressure relief device.This device should have a discharge port of atleast 1⁄2-in. MPT size. The relief valve or frangibledisk device must be set to release at 175 psig (see Figure 14).

þ Do not pressurize the system beyond 150 psig fieldleak test pressure. When field testing a system forleaks, 150 psig is an adequate test pressure.

þ Disconnect the nitrogen cylinder and evacuate thesystem before connecting the refrigerant container.Disconnect the nitrogen cylinder, release thepressure in the system, and evacuate the systembefore connecting a refrigerant cylinder to thesystem. The higher-pressure vapor in the systemcan cause the refrigerant cylinder to explode.

COMPRESSOR MISUSE

Failure to follow the manufacturer’s instructions cancause damage to the compressor. This damage mayincrease the risk of terminal venting with ignitionduring the life of the compressor. (Refer to pages 3through 5 for more information about terminalventing with ignition.)

During system evacuation

þ Never use a compressor to evacuate a system.Instead, use a high-vacuum pump specificallydesigned for that purpose (see Figure 15).

þ Never attempt to start the compressor while it is under deep vacuum. Always break a vacuumwith refrigerant charge before energizing thecompressor.

Failure to follow these instructions can damage thehermetic terminal block. As always, in order to avoidserious injury or death from terminal venting withignition, never energize the compressor unless theprotective terminal cover is in place and securelyfastened.

During system charging

Failure to properly chargethe system can result inserious injury or deathfrom explosion or fire.Always follow theseprecautions when charginga system:

þ Do not operate thecompressor without arefrigerant charge in the system. Operatingthe compressor withouta charge in the systemcan damage thehermetic terminalblock. As always, toavoid serious injury ordeath from terminalventing with ignition,

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To system

Relief valve175-psig setting

Regulatingvalve

Gauges

Figure 14. Dry nitrogen cylinder with attached pressure-regulating andrelief valves and pressure gauges needed for leak-testing and purging

never energize the compressor unless theprotective terminal cover is in place and securelyfastened.

þ Always use the proper refrigerant for the system.Use only the serial label refrigerant whencharging the system. Using a different refrigerantcan lead to excessive system pressures and resultin an explosion. The use of any refrigerant otherthan the serial label refrigerant will void thecompressor warranty.

þ Do not overcharge a refrigeration or airconditioning system. Overcharging a refrigerationor air conditioning system can result in anexplosion. To avoid serious injury or death, never overcharge the system. Always use propercharging techniques. Limit charge amounts tothose specified on the system equipment seriallabel or in the original equipment manufacturer’sservice information.

Overcharging the system can immerse thecompressor motor, piston, connecting rods, andcylinders in liquid refrigerant. This creates ahydraulic block, preventing the compressor fromstarting. The hydraulic block is also known as“locked rotor.”

Continued supply of electricity to the system causesheat to build up in the compressor. This heat willeventually vaporize the refrigerant and rapidlyincrease system pressure. If, for any reason, thethermal overload protector fails to open the electriccircuit to the compressor motor, system pressure canrise to high enough level to cause the compressorhousing to explode or rupture.

USE IDENTICAL REPLACEMENT PARTS

Flammable refrigerant compressors use an enclosedPTC start relay and a sealed thermal protector (seeFigures 16 and 17). The PTC start relay does notspark like some other start-assist devices.

The sealed thermal protector is also not a source of ignition. To reduce the risk of fire or explosion,always replace these components with identical parts.

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Figure 17. Sealed thermal protector

Figure 16. PTC start relay

Figure 15. High-vacuum pump

Be safe with flammable refrigerants

þ Monitor: Use a combustible gas monitor.

þ Ventilate: Ventilate the service area.

þ Eliminate: Eliminate sources of ignition.

Know the facts about flammable refrigerants

þ Flammable refrigerants have no odor.

þ A sudden release can mean a flammableconcentration.

þ Just a spark can cause a fire or explosion.

þ A protective terminal cover will not preventterminal venting with ignition.

Don’t get burned by compressor terminalventing with ignition (flammable ornonflammable refrigerants)

þ Hear sizzling, sputtering, or popping? Get away!

þ Tripped breaker? Check for ground fault beforeresetting.

þ Cover missing? Condemn the compressor untilthe cover is replaced.

þ Taking the cover off? Disconnect power first.

1666 Rand Road Des Plaines, IL 60016 800-297-5660 www.rses.org

FLAMMABLE REFRIGERANTS SAFETY REVIEW