Routine Repair; Repairs To Refrigerant Leakage - Gree A Series Service Manual

A Series Modular-type Air-cooled (Heat Pump) Chiller
7.5

Routine Repair

7.5.1

Repairs to Refrigerant Leakage

When soapsuds often used to detect leakage of a refrigeration system is applied to possible
leakage points. If there are bubbles, leaks occur and need repairs by brazing. If soapsuds
does not work, an electronic leak detector is an alternative. Intake and exhaust pressures
indicate refrigerant charge. If leaks exist or parts are going to be replaced, leakage test must
be taken. Refrigerant charges in two following cases should be treated in different manners.
(1)Full leaks
A leak test for the system must be taken with high-pressure nitrogen (15～20 kg) or refrig-
erant. If brazing is needed, gases in the system must be evacuated. The system must be
treated with vacuum pumping before refrigerant charges.
1) Connect evacuation pipes with fluorine nozzles at low-pressure and high-pressure
sides;
2) Vacuumize the system piping by a vacuum pump.
Procedures (one system as an example):
Step 1: Remove the high-pressure nitrogen that was used for the leak test.
Step 2: Fix pressure gauges to fluorine nozzles of high-pressure and low-pressure
valves (note: vacuum pumping should be done with both valves in the meantime.). Ei-
ther of two dials must register low pressures since only its readings indicate vacuum.
Step 3: Turn on switches at low-pressure and high-pressure sides. Start a vacuum
pump let it continues for 0.5～1.0 hour after the reading of a pressure gauge falls to
-1bar;
Step 4: Close the valves connected to the vacuum pump shown in the figure above and
then shut down the pump (notice: it must be done in this order, or gases will enter the
system again.)
Step 5: Take a pressure test to make sure that the pressure of the system is no less
than 80Pa and will not noticeably rebound within 1 hour.
Up to now, vacuum pumping has been finished.
3) Keep the pressure for 30 minutes, and charge refrigerant when the pressure is no more
than 100Pa. Start charging according to the proper volume indicated by the nameplate
and main technical parameters table.
Fig 7-1 Vacuum pumping
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