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Leakage Test with Nitrogen for Refrigerant Pipes
Prerequisites
- Refrigerant pipes have been welded.
- The needle valve plugs are tightened.
- The measuring range of a pressure gauge must be at least 4.0 MPa, and the rubber hose must withstand a pressure of at least 4.5 MPa.
- Only nitrogen can be used for pressure preservation and leakage detection.
- During pressure preservation, do not remove the rubber hoses and pressure gauges; otherwise, nitrogen may leak.
- When an air-cooled outdoor unit or a water-cooled module is connected to the outdoor side, perform the same operations on the refrigerant side for nitrogen injection and pressure preservation.
Procedure
- Connect the rubber hoses, pressure gauges, reducing valve, and nitrogen cylinder to the device. The pressure gauges and reducing valve are closed.
- If no low temperature component is installed on the outdoor side, connect pipes as shown in Figure 4-77, and charge nitrogen into the system from the low-pressure and discharge pipe needle valves simultaneously.
- If a low temperature component is installed on the outdoor side, connect pipes as shown in Figure 4-78, and charge nitrogen into the system from the low-pressure, discharge pipe, and liquid pipe needle valves simultaneously.
- Open the pressure gauges and reducing valve. Inject 3.0 MPa nitrogen and preserve the pressure for 24 hours. The system pressure should stay constant under unchanging ambient temperature conditions. If there is considerable temperature change, perform the test again.
The outlet pressure of the reducing valve should be within 3.0 MPa; otherwise, components may be damaged.
- If the pressure decreases, find out and repair the leakage point by using soap water or a halogen leak detector. If the pressure is preserved properly, exhaust nitrogen from the three positions shown in Figure 4-61.
For scenarios where a container is transported without refrigerant, keep 0.2 to 0.6 MPa of nitrogen in the pipeline.
