Figure 2-3. service unit connected to power plant.
200 microns of Mercury absolute
3. Attach vacuum hose (20 feet in length) to
cannot be obtained or held for two
fitting F4 on service unit and to power plant compressor
hours, leakage in refrigeration
suction purge valve.
system is indicated. Check for leak
4. Open valve V4 on service unit.
(para (a) above 1.
Operate vacuum pump and evacuate
vacuum pump on service unit.
refrigeration system to a pressure of 200 microns
6. Place power switch on service unit (fig. 2-
Mercury, absolute, as indicated on vacuum gauge GA4.
2) in ON position and place heater vacuum pump switch
Maintain pressure of 200 microns, or less, for a minimum
on service unit in VAC PUMP position.
of two hours.
Close service valve on power plant
refrigerant receiver and close compressor suction purge
Close valve V4 on service unit to
valve on power plant compressor.
obtain accurate measurement of
pressure in refrigeration system on
vacuum gauge GA4. If pressure of