Part 8 Vacuumization And Desiccation For The Refrigerant System; Air-Tightness Test; Importance Of The Air-Tightness Test; Procedure For Performing The Air-Tightness Test - Gree Ultra Heat GMV Multi VRF Heat Pump Series Service Manual

Ultra Heat GMV VRF Technical Service Manual
PART 8 VACUUMIZATION AND DESICCATION FOR THE
REFRIGERANT SYSTEM
Works for the refrigerant system include cleaning and desiccating the pipes, performing an
air-tightness test, and affusing refrigerant.

1 AIR-TIGHTNESS TEST

1.1 Importance of the Air-tightness Test

Air-tightness of the multi-module air conditioning system mainly refers to the tightness of the
refrigerant pipes, which ensures secure and reliable running of the air conditioner.
Refrigerant leakage may affect functions of the air conditions or even damage the compressor and
make the system to break down. Therefore, an air-tightness test must be performed. If refrigerant
leakage is detected after the system is installed, it is very difficult to locate the leaking point as the
suspending ceiling has been decorated. Therefore, the air-tightness test must be performed before
ceiling sealing for indoor decoration is finished.

1.2 Procedure for Performing the Air-tightness Test

Stop valves of the gas and liquid pipes of the ODU are turned off at delivery.
Before test, apply a small amount of required lubricant on the block nut and pipe terminals and use
two wrenches to fix the block nut.
The ODU pipes cannot be connected when the air-tightness test is being performed.
The test pressure for R410A system is 4.0 MPa. Use dry nitrogen as media for the air-tightness test.
Increase the pressure slowly by following the steps below:
Step 1: Increase the pressure to 0.5 MPa. Stop for 5 minutes and then perform air-tightness check.
Major leakage may be detected.
Step 2: Increase the pressure to 1.5 MPa. Stop for 5 minutes and then perform air-tightness check.
Minor leakage may be detected.
Step 3: Increase the pressure for R410A system to 4.15 MPa. Stop for 5 minutes and then perform
strength check. Slight leakage or blow holes may be detected. After increasing the pressure to the test
pressure, keep the pressure for 24 hours and check whether it decreases. If the pressure does not
decrease, it meets the requirement.

1.3 Precautions

(1) The measuring range of the test pressure gauge for R410A system must be above 4.5 MPa.
(2) Record the value displayed on the pressure gauge, ambient temperature, and test time.
(3) Pressure correction: The pressure changes by 0.01 MPa when the temperature changes by 1° C.
(4) The pressure meets the requirement if it does not change.
(5) If the pressure must be kept for a long time, decrease the pressure to 0.5 MPa or lower. High
pressure for a long time may cause leakage at the welding point or safety hazard.
(6) Before performing the air-tightness test to the refrigerant pipes, do not conduct insulation or
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INSTALLATION