Reasons and maintenance methods for the inability of the low-temperature temperature of the high-low temperature test box to be constant

Why can't the temperature be constant during the test of the high and low temperature test chamber? The temperature of the high and low temperature test box can not be constant during the low temperature test. When the high and low temperature box is tested, the temperature cannot be maintained. What is the reason why the temperature of the high-low temperature circulation box cannot be maintained?

First, observe whether the refrigeration compressor of the high and low temperature test box can be started during the operation of the high and low temperature box. If the compressor of the high and low temperature box can be started during the operation, it indicates that the electrical circuit from the main power supply to each high and low temperature box compressor is Normally, there is no problem with the electrical system. When there is no problem with the electrical system of the high and low temperature test box, continue checking the refrigeration system. First, check the two groups of refrigeration compressors in the high and low temperature tanks. If the exhaust and suction pressures of the low temperature (R23) compressors are lower than normal, and the suction pressure is in an empty state, this indicates the cooling of the main refrigeration units. The dose is clearly insufficient. Touch the exhaust and suction piping of the R23 compressor of the main unit of the high and low temperature box. If you find that the temperature of the exhaust pipe is not high, the temperature of the suction pipe is not low (unfrosted). The lack of host group R23 refrigerant is also illustrated.

One of the high and low temperature test boxes 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. In the initial stage of the temperature maintenance period, the two units still work simultaneously. When the temperature is initially stabilized, the auxiliary units stop working, and the host group maintains the temperature drop and stability. If the host group R23 is leaked, the cooling effect of the host group will be small. Since the two units work at the same time during the cooling process, there is no phenomenon that the temperature cannot be stabilized, and the indicated cooling rate is reduced. In the temperature hold stage, once the auxiliary unit stops working, the host group nor refrigeration, air temperature in the high and low temperature will rise slowly, when the temperature rises to a certain extent, the control system will start another auxiliary unit to cool down, then The auxiliary unit stopped working again. If so, there would be a failure phenomenon that the low temperature could not be maintained. At this point, it has been confirmed that the cause of the failure of the high-low temperature tank is the leakage of the refrigerant R23 of the low-temperature (R23)-class unit of the main refrigeration unit.

High and low temperature test box maintenance method: check the leakage of the refrigeration system of the high and low temperature test box, use a combination of leak detector and soapy water to check the leak point, if it is found that the valve stem of the hot gas bypass solenoid valve is cracked If there is a slight gap, replace the solenoid valve. If any leaks are found in other places, then use the oxygen welding to repair the leakage at the leak. Then recharge the system with fluorine, and the system operation will return to normal.

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