United Technologies Carrier TRANSICOLD 68RM35-604-20, Операция и обслуживание

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4-4
T-288
condense more liquid and raise head
pressure.
NOTE
Refrigerant will flow from the system to the
cylinder until the pressures equalize. It is
possible to remove more refrigerant by
cooling the refrigerant cylinder
in a
container of ice.
8. Backseat the liquid line valve and remove
cylinder hose.
9. Service or replace the necessary component
in the system.
NOTE
When opening up the refrigerant system,
certain parts may frost. Allow the part to
warm to ambient temperature before
dismantling.
This avoids internal
condensation which puts moisture in the
system.
4.6 REFRIGERANT LEAK CHECK
To check for leaks in the refrigeration system,
perform the following procedure.
A refrigerant leak check should always be
performed after the system has been opened to
replace or repair a component.
1. On units equipped with liquid solenoid valve
(LSV), it will be necessary to externally power
the solenoid to open the valve and leak check
properly.
2. If system is without refrigerant, charge system
with refrigerant to build up pressure between
30 to 50 psig (2.1 to 3.5 kg/cm
@
).
NOTES
It is recommended that the appropriate
refrigerant used, be used to pressurize the
system.
3. Add sufficient nitrogen to raise system
pressure to 150 to 200 psig (10.5 to 14.1
kg/cm
@ ).
4. Check for leaks. The recommended procedure
for finding leaks in a system is with a halide
torch or electronic leak detector. Testing joints
with soap suds is satisfactory only for locating
large leaks.
5. Repeat the entire procedure if necessary.
6. Evacuate and dehydrate the system as
outlined in section 4.7.
7. Remove the refrigerant and nitrogen used to
pressurize the system prior to leak repair.
8. Charge the unit as outlined in section 4.8.
4.7 EVACUATION AND DEHYDRATION
Proper evacuation and dehydration procedures
are imperative when service repairs or component
replacement are performed on the system to
ensure
proper unit performance and long
compressor life.
The results of improper evacuation are harsh.
Noncondensible gases in the system result in high
head pressure; moisture may cause ice blockage
at the expansion valve; moisture and refrigerant
may react to form an acid. This acid may cause
copper plating of the bearing surfaces and
eventual compressor failure.
a. Equipment Needed
1. Vacuum Pump - A good vacuum pump (
minimum of 5 cfm volume displacement, at
atmospheric pressure) A pump of this capacity is
available through the Carrier Service Parts, CTD
P/N 07-00176-01.
2. Thermistor Vacuum Gauge - A thermistor
vacuum
gauge (electronic vacuum gauge)
measures the low absolute pressures necessary
to remove moisture from the system. A compound
gauge (manifold gauge set) is not recommended
because of it’s inherent inaccuracy. A vacuum
gauge is available from a refrigeration supplier.
3. Evacuation Hoses - Three 3/8” evacuation
hoses, the length to be determined by the
application of the service set-up. 3/8 to 1/4 adapter
connector are also needed to make compressor
connections. (Evacuation hoses and adapters are
available from your local refrigeration supplier.)
Do not use standard refrigeration hoses to
evacuate. These hoses are designed for
pressure not vacuum and may collapse during
evacuation.
4. Recovery System - A refrigerant recovery
system
is recommended for removing the
refrigerant.
5. Evacuation Manifold - A evacuation manifold
is recommended for connecting the equipment
needed for a proper evacuation. The evacuation
manifold can be made easily as shown in
Figure 4-3.