Refrigerant Pressure Holding Leak Detection Method (essential after system repair): This is the ultimate method to confirm the system's airtightness after repairs, but it can only determine if there is a leak, not precisely locate the leak point. Principle: High-pressure nitrogen gas is introduced into the repaired refrigeration system (oxygen or compressed air is strictly prohibited!). The pressure is then held for a period of time, and the pressure gauge reading is observed for any decrease.
Procedure:
1. Recover all refrigerant from the system.
2. Connect the nitrogen cylinder and pressure regulator, and charge the system with nitrogen gas to the specified pressure (e.g., typical household air conditioners are usually charged to 25-40 Bar).
3. Close the valves and hold the pressure for at least 24 hours.
4. Observe the pressure gauge. If the pressure does not drop significantly, the system is well-sealed; if the pressure continues to drop, there is still a leak, and further leak detection methods should be used.
Advantages: It is the "gold standard" for verifying the overall airtightness of the system and is very reliable.
Disadvantages: It cannot locate the leak point and is time-consuming.
