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Troubleshooting – Refrigerant Compressor
6.2.8
System Flushing, Purging, and Pressure
Testing for Leaks
Failure to properly flush, purge, or pressure test a system
for leaks can result in serious injury or death from
explosion, fire or contact with acid-saturated refrigerant
or oil mists.
Webasto recommends that the system be serviced
using a flush and purge station such as a Robinair
unit or similar equipment designed for R134a
refrigerant systems.
Follow these precautions when flushing/purging a system
or pressure testing a system for leaks:
•
Use flushing products according to the
manufacturer's instructions.
•
To purge a system, use only dry nitrogen.
•
When pressure testing for leaks, use only
regulated dry nitrogen or dry nitrogen plus
trace amounts of the serial label refrigerant,
in this case, R134a.
•
When purging or pressure testing any
refrigeration or air conditioning system for
leaks, never use air, oxygen or acetylene.
•
Oxygen can explode on contact with oil.
•
Acetylene can decompose and explode when
exposed to pressures greater than
approximately 15 PSIG.
•
Combining an oxidizing gas, such as oxygen
or air, with an HCFC or HFC refrigerant under
pressure can result in a fire or explosion.
•
Use a pressure regulating valve and pressure
gauges.
Commercial cylinders of nitrogen contain pressures
in excess of 2000 PSIG at 70°F. At pressures much
lower than 2000 PSIG, compressors can explode
and cause serious injury or death. To avoid over
pressurizing the system, always use a pressure
regulating valve on the nitrogen cylinder discharge
(see Fig. 33). The pressure regulator must be able
to reduce the pressure down to 1 or 2 PSIG and
maintain this pressure.
The regulating valve must be equipped with two
pressure gauges:
•
one gauge to measure cylinder pressure, and
•
one gauge to measure discharge or down
stream pressure.
Webasto Product N.A., Inc.
Gauges
Regulating
Valve
DRY
NITROGEN
®
Figure 33. Dry nitrogen cylinder with attached pressure
regulating and relief valves and pressure
gauges needed for pressure testing for leaks
and purging.
•
Use a pressure relief valve.
In addition to a pressure regulating valve and
gauges, always install a pressure relief valve. This
can also be a frangible disc type pressure relief
device. This device should have a discharge port of
at least 1/2" MPT size. The valve or frangible disc
device must be set to release at 175 PSIG (see Fig.
33).
•
Do not pressurize the system beyond 150 PSIG
field leak test pressure.
When field testing a system for leaks, 150
PSIG is adequate test pressure.
•
Disconnect nitrogen cylinder and evacuate the
system before connecting the refrigerant
container.
Disconnect the nitrogen cylinder and release
the pressure in the system before connecting a
refrigerant container to the system. The
higher pressure gas in the system can explode
the refrigerant container.
28
To System
Relief Device
175 PSIG Setting
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