3 Type II: High- and Very-High-Pressure Appliances

Scope and system basics

EPA Section 608 Type II certification covers servicing or disposing of high- or very-high-pressure appliances, except small appliances and motor-vehicle air conditioners (MVACs). Technicians need certification when their work may release refrigerant, including connecting gauges or adding or removing refrigerant.

In a high-pressure system, refrigerant changes between liquid and vapor as it circulates through components such as the evaporator, compressor, condenser, receiver, and accumulator. Refrigerants are not interchangeable, so identify the refrigerant correctly and use its pressure–temperature chart when interpreting pressure.

A pressure reading in psia is an absolute-pressure reading, whereas psig is gauge pressure. The difference is atmospheric pressure—about $14.7$ psi at sea level.

Leak detection and repair

Signs of a leak can include excessive superheat and oil traces around a leak on a hermetic system. Leak-test the system before charging or recharging.

Dry nitrogen alone is an appropriate test gas; a trace of refrigerant with nitrogen can help locate leaks. Never pressurize a refrigeration system with oxygen or compressed air. When using nitrogen, use a pressure regulator and a relief device, and do not exceed the equipment’s pressure limits.

Repair leaks before charging. Traditional Section 608 leak-repair rules apply to appliances containing $50$ pounds or more of ozone-depleting refrigerant. Their annual trigger rates are:

• Industrial process refrigeration: $30\%$.

• Commercial refrigeration: $20\%$.

• Comfort cooling and other appliances: $10\%$.

An appliance over its applicable traditional trigger generally requires corrective action and verification testing.

As of January 1, 2026, separate EPA rules apply to certain appliances containing $15$ pounds or more of an HFC or a covered HFC substitute. The trigger rates are $30\%$ for industrial process refrigeration, $20\%$ for commercial refrigeration, and $10\%$ for comfort cooling, refrigerated transport, and other covered appliances. Residential and light-commercial air-conditioning and heat-pump appliances are excluded from these provisions.

Apply the rules that match the refrigerant and appliance. The older $50$-pound ozone-depleting-substance threshold is not a universal threshold for every refrigerant.

Recovery practices

Recovery removes refrigerant and stores it in an external container; it does not necessarily clean or test the refrigerant. Do not intentionally vent refrigerant during service. Use suitable recovery equipment and follow its instructions.

Recovering liquid first usually speeds recovery. Recovery may also be sped up by chilling the recovery cylinder or carefully warming the appliance or vessel being recovered from, while staying within equipment limits. Use refrigerant-compatible equipment and hoses, and prevent refrigerants from mixing to avoid cross-contamination.

After reaching the required evacuation level, wait a few minutes and check the pressure. A pressure rise can indicate that refrigerant remains in liquid form or is coming out of oil; continue recovery as needed.

Evacuation requirements

For appliances containing more than $5$ pounds, the required evacuation level depends on the appliance pressure class, its full charge, and whether the recovery equipment was made before or after November 15, 1993. The values below are inches of mercury vacuum relative to standard atmospheric pressure; $0$ inches of mercury vacuum corresponds approximately to $0$ psig.

• Very-high-pressure appliance: $0$ inches of mercury vacuum with either pre-November 15, 1993 or post-November 15, 1993 equipment.

• High-pressure appliance with a full charge under $200$ pounds: $0$ inches of mercury vacuum with either equipment period.

• High-pressure appliance with a full charge of $200$ pounds or more: $4$ inches of mercury vacuum with pre-November 15, 1993 equipment; $10$ inches with post-November 15, 1993 equipment.

A high-pressure appliance with a full charge of exactly $200$ pounds belongs in the “$200$ pounds or more” category. These requirements apply to servicing and disposal. Use EPA-certified recovery or recycling equipment where required and follow the equipment manufacturer’s directions. System-dependent recovery equipment may not be used on systems containing more than $15$ pounds of refrigerant.

Leaking appliances and repair conditions

If a leak prevents an appliance from reaching its required evacuation level, isolate leaking components from sound components where possible. Evacuate non-leaking components to the required level. From leaking components, recover to the lowest level attainable without substantially contaminating the refrigerant, but not above $0$ psig.

For a non-major repair that is not followed by venting the appliance to the environment, a high- or very-high-pressure appliance must be at $0$ psig before it is opened. Major repairs require the applicable full evacuation level.

Safety during service

Wear appropriate gloves and eye protection. Liquid refrigerant can cause frostbite, and vapor can displace oxygen. Some refrigerants can affect the heart or produce hazardous decomposition products when exposed to high heat. Use a self-contained breathing apparatus only in extreme situations requiring it, and follow workplace emergency procedures.

Use only approved, reusable recovery cylinders; do not refill disposable cylinders. Never fill a recovery cylinder beyond $80\%$ of its capacity because liquid expansion can create dangerous pressure.

Do not energize a hermetic compressor while it is under vacuum. Follow electrical lockout and equipment procedures before service.

In machinery rooms, follow applicable mechanical-code and ASHRAE Standard 15 requirements for ventilation, alarms, and oxygen-deprivation monitoring. Oxygen-deprivation sensors are also a Type II safety topic.

• Leak-repair trigger rate