Type II - High-Pressure and Very High-Pressure Appliances
Scope
Type II covers high-pressure and very high-pressure appliances other than small appliances and MVACs: split systems, packaged rooftop units, positive-pressure chillers, and anything using R-22, R-134a, R-407C, R-410A, R-32, or R-744. Very high pressure means a saturated pressure above roughly 220 psig at 104°F, or a critical temperature below 104°F. R-410A qualifies, so use only hoses, manifolds, recovery machines, and cylinders rated for it - an R-22 gauge set must never be used on an R-410A system.
Evacuation levels before opening
- Manufactured before November 15, 1993: 15 inches of mercury vacuum (380,000 microns).
- Manufactured on or after that date, charge under 200 lb: 0 psig.
- Manufactured on or after that date, charge 200 lb or more: 10 inches of mercury vacuum (254,000 microns).
Leak repair and records
Appliances holding 50 lb or more that leak above the applicable rate must be repaired within 30 days of discovery, extended to 120 days with a documented repair plan, then verified by test and documented. Chronic leakers must be retrofitted or retired.
Traps
Charging a zeotropic blend such as R-407C as a vapor - it fractionates, so charge liquid. Mixing refrigerants in one cylinder. Pressure-testing with oxygen or shop air instead of dry nitrogen. Assuming 0 psig means the system is clean - the required level still must be reached before the circuit is opened.
Worked example: a 2005 rooftop unit holding 12 lb of R-410A is evacuated to 0 psig, because it was built after 1993 and holds under 200 lb; an identical unit built in 1990 would go to 15 inches of mercury vacuum, about 380,000 microns.