035-19569-101 (0109)
7-4
GB
7.4.2 Leak Testing
After the system has been charged, the system should
be carefully leak tested with a R134a compatible leak
detector to ensure all joints are tight.
Otherwise, it is recommended to perform a leak test
quarterly.
If any leaks are indicated, they must be repaired
immediately. Usually, leaks can be stopped by tightening
fl are nuts or fl ange bolts. However, for any major repair,
the refrigerant charge must be removed.
7.4.3 Vacuum Testing
Vacuum testing should be conducted as follows:
1. Connect a high capacity vacuum pump, with indicator,
to the system charging valve as shown in fi gure 7.3
and start the pump.
2. Open wide all system valves. Be sure all valves to
the atmosphere are closed.
3. Operate the vacuum pump until a wet bulb
temperature of 0°C or a pressure of 5 mm Hg
(absolute) is reached.
4. To improve evacuation circulate warm water (not to
exceed 50°C) through the evaporator and condenser
tubes to thoroughly dehydrate the shells. If a source
of hot water is not readily available, a portable
water heater should be employed. DO NOT USE
STEAM.
A suggested method is to connect a hose between
the source of hot water under pressure and the
evaporator head drain connection, out the evaporator
vent connection, into the condenser head drain and
out the condenser vent. To avoid the possibility of
causing leaks, the temperature should be brought
up slowly so that the tubes and shell are heated
evenly.
5. Close the system charging valve and the stop valve
between the vacuum indicator and the vacuum
pump. Then disconnect the vacuum pump leaving
the vacuum indicator in place.
6. Hold the vacuum in the system for 8 hours; the
slightest rise in pressure indicates a leak or the
presence of moisture, or both. If, after 8 hours the
wet bulb temperature in the vacuum indicator has
not risen above 4.4°C or a pressure of 6.3 mm Hg,
the system may be considered tight.
Be sure the vacuum indicator is valved off while holding
the system vacuum and be sure to open the valve
between the vacuum indicator and the system when
checking the vacuum after the 8 hour period.
7. If the vacuum does not hold for 8 hours within
the limits specifi ed, the leak must be found and
repaired.
Figure 7.3 Unit Evacuation
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