How to check the air tightness of the refrigeration equipment? Introduction to airtightness inspection method for refrigeration equipment

How to check the air tightness of the refrigeration equipment? Introduction to airtightness inspection method for refrigeration equipment

Allow the refrigeration unit to be under a suitable vacuum for a certain period of time to reflect and observe whether air has penetrated the system from the reading of the vacuum gauge to verify the sealing performance of the system. This test must be performed for refrigeration systems where the evaporative pressure gauge is near or below atmospheric pressure. Vacuum testing usually has the following two methods:

1. Vacuum leak test using an external mechanical vacuum pump This method is generally used in small cold storage equipment. The specific steps are as follows:

(1) Unscrew the fine screw plug of the passage for the suction cut-off valve counterclockwise, and rotate the suction cut-off valve rod several times clockwise to make the suction cut-off valve in the three-way state; how to check the airtightness of the refrigeration equipment? Introduction to airtightness inspection method for refrigeration equipment

(2) Connect the vacuum pump to the multi-purpose interface on the suction shut-off valve with a soft connector with a three-way repair valve and a vacuum pressure gauge;

(3) Open all valves in the system (including solenoid valves and manual valves, etc.);

(4) Turn on the vacuum pump power supply, vacuum the system until the reading of the vacuum pressure gauge reaches -0.1MPa, and after the appropriate time, rotate the suction cut-off valve stem counterclockwise to withdraw and tighten;

(5) Maintain 18~24h. If the vacuum is constant, the refrigeration system is considered to be qualified.

2. Self-vacuum test using the compressor in the system For the larger refrigeration system, the vacuum test is usually carried out by this method, and the self-vacuum is performed by the compressor in the system. The specific operation steps are as follows:

(1) First, select the exhaust cut-off valve stem clockwise to make the system lose the circulation passage at the exhaust port of the compressor.

(2) Unscrew the fine screw plug of the multi-purpose passage of the exhaust cut-off valve counterclockwise to make the exhaust port open to the atmosphere.

(3) Open all valves in the system.

(4) Short-circuit the contacts of the low-voltage relay and temporarily remove the protection function (must be restored afterwards).

(5) Start the compressor to discharge the air in the system into the atmosphere (the suction valve of the compressor should be slowly opened to prevent the gas in the system from being discharged, causing the exhaust pressure to be too high and causing high voltage protection, etc.).

(6) Observe the vacuum gauge at the low pressure end until the reading of the vacuum gauge reaches -0.1 MPa. After the appropriate time, the exhaust shutoff valve stem is rotated out and tightened. How to check the air tightness of the refrigeration equipment? Introduction to airtightness inspection method for refrigeration equipment

(7) Maintain for 18~24h, if the degree of vacuum is unchanged, it is qualified. During the test, it should be noted that: 1. When self-vacuum is applied to the pressure-lubricated compressor refrigeration system, the joint of the oil pressure relay should be temporarily forcedly turned on; 2. The self-vacuum time should not be too long, otherwise the compressor The moving parts work at higher temperatures for a long time and are prone to large wear and metal fatigue. 3. In the self-vacuum test, a hose can be connected at the exhaust port and the other end of the hose can be inserted into the oil. In the middle, observe the bubble escape on the oil surface. If no bubbles escape during a long period of time, the vacuum can be stopped, and the vacuum does not change to pass after 24 hours. If the bubble is not long, you can first close the suction valve of the compressor to check whether the compressor itself leaks. If there are no more bubbles in the oil, the compressor itself will not leak, and other parts of the system will leak; the daily bubbles will continue to be generated. , indicating the suction of the compressor, which is often caused by the tightness of the shaft seal.