A technician is recovering R-410A from a high-pressure appliance that normally holds less than 200 pounds, using recovery equipment manufactured after November 15, 1993. To what level must the system be evacuated?

解析

Under 40 CFR §82.156 Table 1, a high-pressure appliance (R-410A, R-22, R-407C, R-404A) with a full charge under 200 pounds must be evacuated to 0 inches Hg vacuum, meaning atmospheric pressure, with post-1993 recovery equipment. 29.9 and 25 inches Hg vacuum are nowhere in the table (low-pressure appliances use 25 mm Hg absolute, a different unit), and 15 psig positive pressure would leave refrigerant behind. Note that R-134a is a medium-pressure refrigerant under §82.152, so an R-134a appliance of the same size would need 10 inches Hg.