Refrigeration Maintenance
111
5. Once a vacuum of 100 microns has been
reached, close the vacuum valve at the
vacuum pump and stop the pump.
6. Wait 5 minutes and then check the vacuum
gauge. The pressure should not exceed 1500
microns.
7. If the pressure rises above 1500 microns in 5
minutes, check all the hoses and connections
for leaks and repeat steps 3 through 6. If the
pressure rises slower this time, moisture may
be present in the hoses. Repeat steps 3 through
6 until the results are satisfactory.
NOTE: Dirty vacuum pump oil will not allow the
pump to reach a deep vacuum. Hoses and
fittings can be isolated one at a time to identify
leaks.
1. Back Seated
2 Vacuum Gauge
3 Vacuum Valve
4. Thermistor
5. Isolation Valve Open
6. Back Seated
Figure 60: Set-up and Test Evacuation Equipment
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5
1
6
AEA2088
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4
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