System cold storage Your system must operate continuously at high capacity. Have you checked the durability and tightness of the system? To ensure efficiency, the system needs to be checked for tightness regularly. Tan Long would like to share refrigeration system leak test procedure standards in this article.
Purpose of refrigeration system leak testing
The refrigerator system consists of 4 main parts (block, condenser, throttle cable, condenser) and auxiliary equipment (filter dryer, liquid separator). These devices are connected by a gas pipe system. If the cabinet operates but is not cold, it may be due to a gas leak in the system. At this time, a leak test must be performed to determine the cause.
Refrigeration system leak test method
The refrigerator system consists of four main parts: block, condenser, evaporator, and capillary tube, along with some additional equipment. Refrigeration system leak test procedure, first, weld the equipment with gas pipes. Use a high pressure gauge and nitrogen gas cylinder to check.
Connect the HI gauge wire to the gas inlet, the intermediate wire to the nitrogen tank, open the HI valve and pump pressure from 200 psi to 300 psi, then close it again. If the pressure remains stable, the system is tight; if it decreases, the system is leaking and the leak needs to be found and fixed.
Closed test procedure
After installation, refrigeration system need to be leak tested to ensure there are no leaks and maintain optimal performance. Here are the steps to follow refrigeration system leak test procedure:
- Prepare: Use nitrogen gas to test the system for tightness. For systems using NH3, unless otherwise specified, air may be used.
- Open all valves: Open all valves in the system, including the solenoid valve. The solenoid valve can be opened by force or by energization to ensure the entire system is open.
- Close the drain valves: Make sure all drain valves in the system are closed to prevent air escape during the leak test.
- Safety valve isolation: Isolate the safety valve to protect the system and avoid unwanted impacts during testing.
- Increase pressure to 10 barG: Use nitrogen to raise the pressure in the system to 10 barG. Check welds and joints with soapy water for leaks. If soap bubbles appear, it is a sign of a leak.
- Mark the leak locations: Mark any leak locations for easy identification and repair later.
- Leak Repair: If leaks are detected, relieve pressure to a safe level and repair leaking joints or welds.
- Increase pressure to 12 barG: After repair, increase pressure to 12 barG. Isolate low pressure system from high pressure system to test each part of the system separately.
- Leak test: Use soapy water to recheck the joints. If leaks are found, repeat the repair step.
- High pressure endurance test: Raise the high pressure to the endurance test level and hold for 5 minutes to ensure the pressure resistance of the system.
- Pressure test leak test: Release high pressure to the leak test level and check the joints with soapy water.
- Pressure maintenance: If no more leaks, hold the test pressure for 24 hours.
- Monitor: After 6 hours, the pressure drops by no more than 0.3 bar. After 18 hours, the pressure does not drop, which is satisfactory.
- Dust and residue discharge: Quickly open the drain valve to push dust and debris out of the system.
- Complete the process: When the high pressure drops to 12 barG, open the high pressure and low pressure valves, discharge the air in the system to outdoor pressure to complete the leak test procedure.
Proper seal testing is an important step in ensuring efficient refrigeration system operation and prolonging the life of the equipment.
Vacuum test procedure for moisture removal
Vacuum testing is an important step after the tightness test to remove air and moisture, ensuring the performance and durability of the refrigeration system. Use a specialized vacuum pump to perform this.
For NH3 system:
- Vacuum: Reduce pressure below 80 mbar (60 mmHg) to remove air and moisture.
- Pressure maintenance: Hold for 24 hours; if the pressure does not change, the system is satisfactory.
- NH3 loading: If not refilling NH3 immediately, add a small amount of NH3 to keep the pressure above 0 barG, preventing air and moisture from entering.
For Freon system:
- First vacuum: Reach pressure below 53 mbar (40 mmHg).
- Second vacuum
- Commercial system: Charge gas to 0 barG pressure, then vacuum a second time below 53 mbar.
- Other systems: Pause for 1-2 hours, then vacuum a second time below 53 mbar.
- Pressure maintenance: Hold for 24 hours; if the pressure does not increase more than 5 mbar (4 mmHg), the system is satisfactory.
- Gas filling: If not refilled immediately, add a quantity to keep the pressure above 0 barG, ensuring the system is sealed and ready for operation.
Conclude
Refrigeration system leak test procedure is an important step to ensure there are no leaks in the system. By using compressed gas such as nitrogen, combined with pressure testing and soapy water testing, this process helps to detect and fix leaks promptly, ensuring efficient operation and prolonging the life of the refrigeration system.
