Air-Tightness Test; Vacuumization And Desiccation For The System; Importance Of The Air-Tightness Test; Procedure For Performing The Air-Tightness Test - Gree GMV-S120WL/A-S Service Manual

9.5.1.3 Air-tightness test

Precautions:
The measuring range of the test pressure gauge for R410A system must be above 4.5MPa.
Record the value displayed on the pressure gauge, ambient temperature, and test time.
Pressure correction: The pressure changes by 0.01MPa when the temperature changes by
1℃.
The pressure meets the requirement if it does not change.
f the pressure must be kept for a long time, decrease the pressure to 0.5MPa or lower. High
pressure for a long time may cause leakage at the welding point or safety hazard.
Before performing the air-tightness test to the refrigerant pipes, do not conduct insulation or
wrapping at the welding or flaring opening joints of the IDU. The pressure must be increased
simultaneously for pipes on outdoor sides and cannot be increased for pipes on one side.
Note: Before performing the air-tightness test, do not conduct insulation or wrapping at the
welding joints.

9.5.1.3.1 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, a 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.

9.5.1.3.2 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 4.15MPa. 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 0.5MPa. Stop for 5 minutes and then perform air-tightness
check. Major leakage may be detected.
Step 2: Increase the pressure to 1.5MPa. Stop for 5 minutes and then perform air-tightness
check. Minor leakage may be detected;
Step 3: Increase the pressure for R410A system to 4.15MPa. 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.

9.5.1.4 Vacuumization and desiccation for the system

9.5.1.4.1 Requirements on the vacuum pump
1）The vacuum pump for different refrigerant systems cannot be the same.
2）The ultimate vacuum degree of the vacuum pump should reach -0.1Mpa.
3）The air discharge capacity of the vacuum pump must be greater than 4L/S.
4）The precision of the vacuum pump must be greater than 0.02mmHg.
5）The system vacuum pump must be equipped with a check valve.
9.5.1.4.2 Procedure and precautions for vacuumization and desiccation
1）Before vacuumization, ensure that the stop valves of the gas pipe, liquid pipes and
high-pressure gas pipe are turned off.
GMV5 Home DC Inverter Multi VRF Units
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