Pressure and leak test of refrigerant system.
After erection of air conditioning plant onboard and finished refrigerant pipe work prior to application
of insulation, pressure/leak test to be performed as follow procedure.
1. Close suction valve and discharge valve of compressor.
2. Open other valves installed on the refrigerant pipe line.
3. Low pressure switch to be isolated from the suction line during this test and ensure that
expansion valves, pressure switches and etc. containing bellows or diaphragms are isolated
from the rest of the plant during the test.
4. Charge N2 gas into entire system through charge valve until the pressure rises up to the test
pressure of 11kg/cm² G. for low pressure side.
(From expansion valve to compressor suction stop valve)
5. Close stop valve just before the expansion valve on the liquid line to separate high pressure
line from low pressure line.
6. Further charge dry N2 gas until the pressure rises up to the test pressure of 21 kg/cm² G. for
high pressure side. (From compressor discharge stop valve to manual stop valve installed just
ahead expansion valve)
7. Keep this condition for twelve(12) hours and check the pressure drop at the end of this test.
The pressure drop should not exceed 0.35 kg/cm² with following temp. correction
P = Po - P(To/T) 0.35 kg/cm2
here, P = Pressure drop (kg/cm²)
Po = Initial pressure (kg/cm²)
To = Initial temperature (°K)
T = Temperature at end of test (°K)
8. In case of pressure drop exceeds 0.35 kg/cm², every joint to be checked by halide torch detector
or soap water. If leakage is detected, the test should be repeated after the leak part repaired.