How to check the air tightness of 40 screw freezer?

Air tightness is related to the cooling effect of the entire 40-screw freezer. Therefore, the manufacturer of 40-pin screw freezer of LushiA (LNEYA) recommends that users do 4 inspections, then how to check the work?

This test is carried out on a refrigeration system with a 40-screw freezer evaporating pressure gauge close to or below atmospheric pressure. The vacuum leak test using an external mechanical vacuum pump is generally used in a small 40-hp screw freezer. When the hour hand unscrews the fine screw plug of the suction cut-off valve passage, turn the suction cut-off valve rod several times clockwise to make the suction cut-off valve in the three-way state; use a soft connector with a three-way repair valve and a vacuum pressure gauge The vacuum pump is connected to the multi-purpose interface on the suction shut-off valve; all the valves in the system (including solenoid valve and manual valve) are opened; the vacuum pump power is turned on, and the system is vacuumed until the reading of the vacuum gauge reaches -0.1MPa. After the appropriate time, the suction shut-off valve stem is rotated counterclockwise to withdraw and tighten; for 18~24h, if the vacuum is constant, the vacuum test of the refrigeration system is considered qualified.

The 40-cylinder screw chiller uses the compressor in the system for self-vacuum test when doing air tightness test. For larger refrigeration systems, vacuum test is usually carried out by this method, and self-vacuum is performed by the compressor in the system. First, the exhaust cut-off valve stem is selected clockwise to the end, so that the system loses the circulation passage at the exhaust port of the compressor. Rotate the fine screw plug of the exhaust passage valve counterclockwise to make the exhaust port open to the atmosphere. Open all valves in the system. Short-circuit the contacts of the low-voltage relay and temporarily remove the protection function (recovery afterwards). Start the compressor and let the air in the system discharge 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.). 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. Hold for 18~24h, if the degree of vacuum is unchanged, it is qualified.

The air tightness check should be checked regularly to check the details of all aspects of the 40 screw freezer from various data.