A supermarket rack system holds 350 pounds of R-404A. Using recovery equipment manufactured after November 15, 1993, to what vacuum must the technician evacuate during recovery?

解析

R-404A is a high-pressure refrigerant: its saturation pressure at 104°F falls inside the 170–355 psia band that 40 CFR §82.152 uses to define a high-pressure appliance. Under §82.156 Table 1, a high-pressure appliance with 200 pounds or more must be evacuated to 10 inches Hg with recovery equipment made on or after November 15, 1993. (b) 15 inches Hg applies only to medium-pressure appliances (R-12, R-134a, R-500) of 200 pounds or more, a trap from pre-2017 guides; (c) 25 mm Hg absolute is the low-pressure level; (d) 4 inches Hg belongs to pre-1993 equipment.