Type II: High-Pressure Appliances
Type II certification covers medium-, high- and very-high-pressure appliances, from residential split systems to supermarket racks and R-134a chillers. This chapter defines the pressure classes the way 40 CFR §82.152 does, lists the §82.156 Table 1 evacuation levels, and reviews the leak-detection and recovery techniques you will use on these systems.
Pressure Classes Defined
40 CFR §82.152 sorts appliances by the refrigerant's liquid-phase saturation pressure at 104°F, not by boiling point. Medium-pressure is 45 to 170 psia (the CFR names R-12, R-134a, R-500, R-114 and R-124). High-pressure is 170 to 355 psia (the CFR names R-22, R-407A, R-407C, R-410A and R-502; R-404A, at about 265 psia, is high-pressure too). Very-high-pressure is above 355 psia, or a critical temperature below 104°F (R-13, R-23, R-503). Type II certification is required to service, maintain, repair, or dispose of all three classes, except for small appliances and motor-vehicle air conditioners, which fall under Type I and Section 609 respectively. Most everyday HVAC and commercial refrigeration work is Type II, so this is the certification most field technicians rely on daily.
Evacuation Levels (§82.156 Table 1)
Before opening a medium-, high- or very-high-pressure appliance for major service or disposal, you must recover refrigerant to the level in 40 CFR §82.156 Table 1, which depends on the pressure class, the full charge and the age of your recovery equipment. With recovery equipment manufactured on or after November 15, 1993: a high-pressure appliance (R-22, R-410A, R-404A, R-407C) goes to 0 in Hg under 200 pounds and 10 in Hg at 200 pounds or more; a medium-pressure appliance (R-12, R-134a, R-500) goes to 10 in Hg under 200 pounds and 15 in Hg at 200 pounds or more; and a very-high-pressure appliance goes to 0 in Hg. With equipment made before that date, the levels are 0 in Hg (very-high-pressure, and high-pressure under 200 pounds) or 4 in Hg (the rest). A 300-pound R-404A rack is therefore 10 in Hg, not the 15 in Hg printed in guides that still use the pre-2017 table.
Leak Detection Methods
Finding leaks quickly protects the charge, the equipment, and the atmosphere. An electronic leak detector is highly sensitive and pinpoints small leaks by sensing refrigerant near a joint. A soap-bubble solution brushed on a suspect fitting reveals larger leaks as growing bubbles. A fluorescent dye added to the system shows leak points under ultraviolet light after the unit runs. An ultrasonic detector hears the hiss of escaping gas. To pressurize a system for leak testing, use dry nitrogen, sometimes with a trace of refrigerant so an electronic detector can sense it, but never use oxygen or compressed air. Always leak-test and repair a system before recharging it, because charging a leaking system simply vents refrigerant and wastes money.
Recovery Techniques for High-Pressure Systems
Recovering a high-pressure system efficiently means managing both liquid and vapor. On a large charge, recover liquid first through the liquid-line port to move the bulk quickly, then switch to vapor recovery to pull the remaining gas down to the required vacuum. Recovering liquid before vapor greatly shortens the job. Non-condensable gases such as air raise head pressure and slow recovery, so purge them and avoid drawing air into the system. Keep hoses short and use low-loss fittings to minimize the refrigerant released when you connect and disconnect. Watch the recovery cylinder weight and never exceed 80 percent fill. If the appliance is very cold or the ambient is low, recovery slows, so warming the appliance slightly or cooling the recovery cylinder can speed the transfer.
Last updated: October 2026
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