1. Visual inspection: When oil stain is found at the joint of the system, there may be a leak here.

2. Soap detection: nitrogen with the pressure of 10-20kg/cm3 can be filled into the system, and soapy water can be coated on all parts of the system, and the bubbling place is the leakage point.

3. Nitrogen detection: Fill the system with nitrogen with the pressure of 10-20kg/cm3, and immerse the system in water, with the bubbling position as the leakage point.

4. halogen lamp leak detection, that is, using liquefied petroleum gas without halogen substances. Ignite the leak detector, hold the gas pipe on the halogen lamp, and the nozzle is close to the place where the system may leak, and the flame color turns purple-blue, indicating that there is a lot of leakage here.

5. Gas differential pressure leak detection method: using the pressure difference inside and outside the system, the differential pressure is amplified by the sensor, and the leak detection result is expressed in the form of digital or sound or electronic signal. There are generally three leak detection methods: vacuum negative pressure leak detection and helium-nitrogen positive pressure leak detection.

6. Electronic leak detection: move the probe to all possible leakage positions. When the leak detection device gives an alarm, it shows that there is a lot of leakage here.

7. Fluorescent leak detection, using the principle that fluorescent agent will emit yellow and green light under the irradiation of leak detection lamp. Add fluorescent agent into the system according to a certain proportion, put on special glasses after the system runs for 20 minutes, and illuminate the outside of the system with a leak detector, and the leakage will show bright yellow fluorescence.