High- and Very High-Pressure Appliance Servicing and Disposal (Type II)
High- and very high-pressure appliance servicing and disposal (Type II)
Type II covers high-pressure and very high-pressure appliances that are not small appliances and not MVACs: split systems, rooftop units, commercial refrigeration racks, and similar equipment using R-22, R-410A, R-134a, R-502, R-13, or R-23. The exam emphasizes evacuation levels, leak repair, pressure testing, and safe charging.
Pressure classes and scope
High-pressure appliances include most commercial and residential AC and refrigeration equipment. Very high-pressure appliances use refrigerants with much higher saturation pressures, such as R-13 or R-23. Small appliances (5 lb or less, hermetic, factory-charged) and motor vehicle air conditioners are outside Type II.
Evacuation targets
For high-pressure appliances, the required evacuation level depends on charge size: 5 to 50 lb requires 10 in Hg vacuum; more than 50 lb requires 15 in Hg vacuum. Very high-pressure appliances require 0 psig. Use a vacuum pump and manifold gauges, and do not rely on the system compressor. Recover refrigerant first; venting is prohibited.
Leak repair and testing
Appliances with 50 lb or more are subject to leak-repair rules. Common leak-rate thresholds are 10% for comfort cooling, 20% for commercial refrigeration, and 30% for industrial process refrigeration. Exceeding the threshold triggers repair within 30 days and follow-up verification. Use dry nitrogen for pressure testing; oxygen and air can explode with oil. Charge blended refrigerants such as R-410A as liquid to avoid fractionation.
Worked example
A 40-lb R-22 rooftop unit is opened for repair. Because the charge is between 5 and 50 lb, evacuate to 10 in Hg vacuum, not 15. If the same job were an 80-lb rack, the target would be 15 in Hg. If it used R-13, a very high-pressure refrigerant, the target would be 0 psig. The reasoning: Type II evacuation levels scale with charge size and pressure class; the venting ban applies throughout.
Traps
Applying the small-appliance 90%/80% rule to Type II. Using 15 in Hg for a 40-lb system. Evacuating only to 0 psig on a normal high-pressure unit. Charging R-410A as vapor. Pressure-testing with air or oxygen. Ignoring leak-repair thresholds.