The high and low temperature test chamber is used to test the performance of materials in various environments, and to test the heat resistance, cold resistance and dry and wet resistance of various materials. Suitable for quality inspection of electronics, electrical appliances, communications, instruments, vehicles, plastic products, metals, food, chemistry, building materials, medical care, aerospace and other products. There will be no refrigeration when using high and low temperature test boxes. Why is this happening? Now briefly explain the reason why the high and low temperature test box is not cooled.
Reason one:
1. Because the temperature cannot be maintained, it is observed whether the refrigeration compressor can be started during the operation of the test chamber, and the compressors can be started during the operation of the environmental test equipment, indicating that the electrical circuit from the main power supply to each compressor is normal and there is no problem with the electrical system.
2. Touch the exhaust pipe and suction pipe of the main compressor by hand, and find that the temperature of the exhaust pipe is not high, and the temperature of the suction pipe is not low (not frosting), which also indicates that the refrigerant of the main compressor is insufficient.
There is nothing wrong with the electrical system. Continue to check the refrigeration system. Firstly, check that the exhaust and suction pressures of the low-temperature compressors of two refrigeration units in the high-low temperature test box are lower than normal, and the suction pressure is in an evacuation state, indicating that the refrigerant dose of the main refrigeration unit is insufficient.
Reason two:
1. The cause of the failure has not been determined, and the cause of the failure is further confirmed in combination with the control process of the test chamber, which has two refrigeration units.
2. One is the main unit and the other is the auxiliary unit. When the cooling rate is high, the two units work at the same time, and at the beginning of the temperature maintenance stage, the two units still work at the same time. When the temperature is initially stable, the auxiliary machine stops working and the main machine keeps the temperature stable. If the main engine group R23 leaks, the refrigeration effect of the main engine group is not great. Because the two units work at the same time during the refrigeration process, there is no temperature instability, indicating that the cooling rate is reduced. In the temperature maintenance stage, once the auxiliary machine stops working and the main machine has no refrigeration function, the air in the test chamber will slowly rise. When the temperature rises to a certain extent, the control system will start the auxiliary unit to cool down, and then the auxiliary unit will stop working. So far, it has been confirmed that the cause of the production failure is the refrigerant leakage of the low temperature unit of the main engine.