Standing Vacuum Test
When performing the stan ding vacuum test, or mach ine dehydration, use a manome ter or a
wet bulb indicator. Dial gages cannot indicate the sma ll amount of acceptable leaka ge during a
short period of time.
1. Attach an abs olute pressure ma nometer or wet bulb indicator to the machine.
2. Evacuate the vessel (see Pumpout and Refrigerant Transfer Procedures section) to at least
18 in. Hg vac, ref 30-in. bar ( 41 kPa), using a vacuum pump or the pump-out unit.
3. Valve off the pump to hold t he vacuum and record the manome ter or indicat or reading.
4.a. If the leakage rate i s less than 0.05 in. Hg (.17 kPa) in 24 hours, the machine is s uf fi-
ciently tight.
b. If the leakage rate exceed s 0.05 in. Hg (.17 kPa) in 24 hours, repressurize the vessel and
test for leaks. If refrig erant is available in the ot her vessel, pressuri z e by fo llowing Steps
2-10 of Return Ref rigerant to Normal Oper at ing Conditions sect ion . If not, use nitrogen
and a refrigerant trace r. Raise the vessel pressu re in increments until th e lea k is
detected. If refriger an t is used, the maximum gas pr es s ur e is approximately 70 psig
(483 kPa) at normal ambien t temperature.
5. Repair leak, retest , and proceed with dehydr at ion.