4251. The pressure, in a low pressure refrigeration system about to be opened for a major repair, should be brought to what value before the system can be opened for repairs if the recovery unit was manufactured on or after Nov. 15, 1993?

EPA regulations require low-pressure refrigeration systems, when repaired with recovery equipment manufactured on or after November 15, 1993, to be evacuated to 25 mm of Hg absolute before opening for repairs to ensure complete refrigerant recovery.