EPA 608 Technician Certification Concept Review

Overview

This chapter explains why EPA controls refrigerants at all. You will learn how some refrigerants damage the ozone layer, how to tell the three main refrigerant families apart, and why non-exempt substitute refrigerants such as HFCs still may not be vented. It also covers what to expect when a system is changed to a substitute refrigerant.

The ozone layer sits in the stratosphere and blocks much of the sun's ultraviolet (UV) light. CFCs and HCFCs are stable enough to drift up there, where strong UV light breaks them apart and frees chlorine. One chlorine atom can destroy many ozone molecules. Less ozone means more UV at ground level, which raises the risk of skin cancer and cataracts.

CFCs such as R-12 and R-11 contain chlorine and no hydrogen, so they have the highest ozone depletion potential (ODP). HCFCs such as R-22 and R-123 contain hydrogen too, so their ODP is lower. HFCs such as R-134a and R-410A contain no chlorine and have zero ODP, but many have a high global warming potential (GWP).

There is no true drop-in replacement for an older refrigerant. A retrofit may need a different oil, such as ester (POE) oil for HFCs instead of mineral or alkylbenzene oil. Some blends fractionate, which means their parts leak at different rates, so they are charged as a liquid.

Overview

This chapter covers the laws behind Section 608. It explains the Montreal Protocol and the U.S. phaseout dates, the venting prohibition, who may buy refrigerant, when recovered refrigerant must be reclaimed, and which certification type each job needs. It ends with records, penalties, and the newer HFC leak repair rule.

The Montreal Protocol is the international treaty that phases out ozone-depleting substances. In the United States, production and import of CFCs ended on January 1, 1996, and production and import of R-22 ended in 2020. Existing refrigerant can still be used for service if it was made earlier or has been recovered and recycled or reclaimed.

No one may knowingly vent CFC, HCFC, or non-exempt substitute refrigerants such as HFCs while servicing or disposing of equipment. Only small de minimis releases during proper recovery are allowed. Refrigerant may be sold only to certified technicians or their employers, with a few exceptions such as small cans for car air conditioning. Used refrigerant sold to a new owner must be reclaimed by a certified reclaimer.

Type I covers small appliances, Type II covers high- and medium-pressure appliances, Type III covers low-pressure appliances, and Universal covers all three. Certification does not expire. Clean Air Act penalties are counted per day for each violation. Since January 1, 2026, a separate EPA rule (40 CFR Part 84) also requires leak repair on many appliances with 15 pounds or more of high-GWP HFC refrigerant.

Overview

This chapter reviews how a refrigeration system moves heat and how technicians measure and handle the refrigerant in it. You will follow the refrigerant around the cycle, read manifold gauges, change gauge pressure to absolute pressure, and learn the difference between recover, recycle, and reclaim.

The compressor squeezes low-pressure vapor into high-pressure vapor. In the condenser the vapor gives off heat and becomes a high-pressure liquid. The metering device drops the pressure, and in the evaporator the low-pressure refrigerant boils and absorbs heat. It returns to the compressor as a low-pressure vapor. The part from the compressor to the metering device is the high side; the rest is the low side.

On a manifold, the blue compound gauge and hose connect to the low side, the red gauge and hose to the high side, and the yellow center hose to the recovery machine, vacuum pump, or cylinder. A compound gauge reads both pressure and vacuum. To change gauge pressure (psig) to absolute pressure (psia), add 14.7.

To recover is to remove refrigerant and store it. To recycle is to clean it for reuse by the same owner. To reclaim is to bring it to new-product purity and prove it by testing. Shorter, wider hoses speed recovery, and refrigerants must never be mixed. After a repair, the system is evacuated to remove air and moisture before charging.

Overview

This chapter covers how to protect yourself and others when handling refrigerant and cylinders. It explains the health risks of refrigerant, the protective equipment to wear, how to tell recovery cylinders from disposable ones, safe filling, safe leak testing, and how to label cylinders for shipping.

Most refrigerant vapor is heavier than air, so a large leak in a basement or closed room can push out oxygen and cause suffocation. Breathing high levels can also cause an irregular heartbeat. Liquid refrigerant can cause frostbite, so wear gloves and safety glasses. A self-contained breathing apparatus (SCBA) is for extreme cases such as a large leak in an enclosed area.

Recovery cylinders are refillable, DOT-approved, and painted gray with a yellow top. Never fill one more than 80 percent full of liquid, because the liquid expands as it warms. Disposable cylinders must never be refilled. Never heat a cylinder with an open flame.

Pressurize for leak tests with nitrogen, never oxygen or compressed air, and always use a pressure regulator and a relief valve. Before shipping, label the cylinder with the refrigerant type and the DOT hazard classification.

Overview

This chapter covers the rules for small appliances, the equipment Type I technicians work on. You will learn what counts as a small appliance, how much refrigerant must be recovered, the special rules for Type I tests, and what happens to refrigerant when old appliances are scrapped.

A small appliance is fully built, charged, and hermetically sealed in a factory with 5 pounds of refrigerant or less. Examples are household refrigerators and freezers, window air conditioners, dehumidifiers, water coolers, and vending machines. A split system charged in the field is not a small appliance.

With recovery equipment made on or after November 15, 1993, recover 90 percent of the refrigerant if the appliance's compressor works, or 80 percent if it does not. With older equipment, recover 80 percent. Evacuating to 4 inches of mercury vacuum also meets the rule. Recovery equipment must be certified.

A Type I-only test may be given by mail. It needs 84 percent to pass and cannot count toward Universal. People who only dispose of small appliances do not need certification, but the refrigerant must still be recovered. The final processor, such as a scrap yard, must recover the refrigerant or keep signed statements for three years.

Overview

This chapter covers how Type I technicians actually get refrigerant out of small appliances and how they stay safe while doing it. It compares self-contained and system-dependent recovery, explains how to handle a compressor that works or does not, and covers access valves, identifying refrigerants, and heat and fire hazards.

Self-contained (active) recovery equipment has its own compressor. System-dependent (passive) equipment relies on the appliance's compressor or pressure, and it may not be used on appliances with more than 15 pounds. If the appliance's compressor works, run it during passive recovery. If it does not, install access valves on both the high and low sides, and warm and sharply tap the compressor to free refrigerant from the oil. A vacuum pump may be used only with a non-pressurized container.

Solderless piercing valves tend to leak, so remove them when service is done. Read the nameplate to identify the refrigerant, and compare pressure and temperature with a PT chart. A pressure above the chart value points to air or other noncondensables. R-134a is the common replacement for R-12 in household refrigerators.

Refrigerant exposed to a flame or very hot surface can break down into toxic and corrosive gases, so recover it before brazing and keep the area ventilated. Hydrocarbon refrigerants such as isobutane (R-600a) are flammable, so keep sparks and flames away.

Overview

This chapter covers finding and fixing leaks in high-pressure equipment and the leak repair rules for large appliances. It explains common signs of leaks, which gas to use for a leak test, the trigger leak rates, repair and testing deadlines, inspections, and records.

Oil traces around joints and fittings and excessive superheat are common signs of a leak. Always leak test before charging. Nitrogen alone is the best test gas; nitrogen with a trace of R-22 is next, and both are better than pure refrigerant.

Under 40 CFR 82.157, appliances with 50 pounds or more of CFC or HCFC refrigerant must be repaired when the yearly leak rate is over 20 percent for commercial refrigeration, 30 percent for industrial process refrigeration, or 10 percent for comfort cooling and others. Since January 1, 2026, 40 CFR Part 84 applies the same rates to many appliances with 15 pounds or more of high-GWP HFC refrigerant.

Leaks must be repaired within 30 days, or 120 days if an industrial process shutdown is needed, and confirmed by an initial and a follow-up verification test. An owner who will not repair must make a retrofit or retirement plan within 30 days and finish it within a year. The leak rate is calculated each time refrigerant is added, and records are kept at least 3 years.

Overview

This chapter covers how far high- and medium-pressure appliances must be evacuated before they are opened, and how to recover refrigerant quickly and cleanly. The required level depends on the appliance's pressure class, whether the charge is under or over 200 pounds, and when the recovery equipment was made.

With recovery equipment made on or after November 15, 1993, a high-pressure appliance under 200 pounds must reach 0 inches of mercury, and one with 200 pounds or more must reach 10 inches of mercury vacuum. Medium-pressure appliances need 10 inches under 200 pounds and 15 inches at 200 pounds or more. With older equipment, the levels are 0 or 4 inches. Very high-pressure appliances need 0 inches.

A non-major repair that is not followed by evacuation to the air needs only 0 psig, and an oil change needs 5 psig or less. A major repair removes the compressor, condenser, evaporator, or auxiliary heat exchange coil, or leaves an opening of more than 4 square inches open for more than 15 minutes. If leaks prevent reaching the level, isolate leaking parts and evacuate them as low as possible, no higher than 0 psig.

Recover liquid first, chill the recovery cylinder, or warm the appliance to speed recovery. After reaching the level, wait a few minutes; a pressure rise means refrigerant is still there. System-dependent equipment may not be used on appliances over 15 pounds. Clear the machine and change the filter before switching refrigerants.

Overview

This chapter covers the equipment and refrigerants Type II technicians work with and the safety points that go with them. It explains the pressure classes, the main system parts and the refrigerant state in each, how to identify a refrigerant, and why some actions can damage equipment.

EPA classes appliances by the refrigerant's liquid saturation pressure at 104°F. High-pressure refrigerants (170 to 355 psia) include R-22, R-407C, and R-410A. Medium-pressure (45 to 170 psia) includes R-134a and R-12. Very high-pressure includes R-23 and R-13. Type II covers all three of these classes.

The receiver stores high-pressure liquid after the condenser. The accumulator in the suction line keeps liquid away from the compressor. The suction line carries low-pressure vapor and the discharge line carries high-pressure vapor. Read the nameplate to identify the refrigerant, and add 14.7 to a gauge reading before using a PT chart in psia.

Never start a hermetic compressor while the system is in a deep vacuum, because the motor windings can be damaged. Hydrocarbons are not approved for retrofitting these systems. Under ASHRAE Standard 15, equipment rooms need a refrigerant or oxygen-deprivation sensor with an alarm.

Overview

This chapter covers leaks in low-pressure chillers, which behave differently from leaks in other systems. You will learn why air gets in instead of refrigerant getting out, how to spot a leak, how to raise pressure safely for a leak test, and the leak repair rules for large chillers.

Low-pressure refrigerants such as R-11, R-123, and R-113 have a liquid saturation pressure below 45 psia at 104°F. Much of a running low-pressure chiller is below atmospheric pressure, so a leak lets air and moisture in. A purge unit that runs much more than usual is a key sign of a leak.

To leak test, raise the pressure first with controlled hot water or a built-in heating device, and use nitrogen only if needed. Do not go above 10 psig, because the rupture disc is usually set at 15 psig.

Chillers with 50 pounds or more of an ozone-depleting refrigerant such as R-123 must be repaired when the yearly leak rate is over 10 percent for comfort cooling or 30 percent for industrial process refrigeration. After exceeding the rate, comfort cooling chillers need a leak inspection once per calendar year. Leaking 125 percent or more of the charge in a year must be reported to EPA by March 1.

Overview

This chapter covers how to remove refrigerant from a low-pressure chiller and how to recharge it without damage. It explains the required evacuation level, the order for recovering liquid and vapor, how to protect the tubes from freezing, how to handle oil, and how to pressurize for small repairs.

Low-pressure appliances must be evacuated to 25 mm Hg absolute, which is about 29 inches of mercury vacuum. The level is the same with older and newer recovery equipment. Recover the liquid first, then the vapor, because a large chiller holds a lot of refrigerant as vapor. Keep water moving through the tubes or drain it so it does not freeze, and heat the oil to 130°F before draining it.

For a non-major repair, the chiller is raised to 0 psig before opening. Use heat to raise the pressure; nitrogen may be added after heat only for refrigerants that boil above 85°F, such as R-113. After reaching the required vacuum, wait a few minutes; if pressure rises, keep recovering. Recovery devices for low-pressure use commonly cut out at about 10 psig.

When recharging after evacuation, add vapor first so the water in the tubes does not freeze, and then add liquid. Centrifugal chillers are charged through the evaporator charging valve.

Overview

This chapter covers how low-pressure chillers are built and the safety rules for the rooms they sit in. You will learn why they run in a vacuum, what the purge unit and rupture disc do, which refrigerants they use, and what to watch for during a large leak.

Low-pressure refrigerants such as R-123 boil at low temperatures only under vacuum, so the evaporator of a running chiller is below atmospheric pressure. R-123, an HCFC, replaced R-11, a CFC, in many of these chillers. R-123 boils at about 82°F at atmospheric pressure, so a shut-down chiller in a 75°F room shows a slight vacuum.

Air and moisture that leak in collect at the top of the condenser. The purge unit draws from there, removes the noncondensables, and returns refrigerant to the system. The rupture disc on the evaporator protects the chiller from overpressure and is usually set at 15 psig.

Refrigerant vapor is heavier than air and can displace oxygen in a closed machinery room. Under ASHRAE Standard 15, a machinery room with R-123 needs a refrigerant sensor with an alarm. Use a self-contained breathing apparatus for a large leak.