How to solve the temperature instability in high and low temperature test chamber

Cause of failure: Low temperature instability in low and high temperature test chamber Failure analysis: First, observe whether the high and low temperature box refrigeration compressor can be started during the operation of the high and low temperature test box. If the compressor of the high and low temperature box can start during operation, it indicates that From the main power supply to the electrical circuit of each high and low temperature box compressor is normal, there is no problem with the electrical system. When there is no problem with the electrical system of the high and low temperature box, continue to check 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 relatively high, the two units work simultaneously. At the beginning 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 maintenance phase, once the auxiliary unit stops working, the main unit has no cooling effect, and the air temperature in the high and low temperature 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 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 chamber maintenance method: check the cooling 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 leakage is found elsewhere, complete the welding with the oxygen weld and recharge the system with fluorine. The system operation can return to normal.

It can be seen from the above that the analysis and judgment of the failure phenomenon of the low-temperature test chamber's unreliable low temperature can be analyzed and judged basically from the easy to the difficult, first outside and back, and then after the electrical air-cooling. Understand the principle and working process of the high and low temperature chamber is to analyze the basis for fault diagnosis. Only in-depth understanding of the working principle and working process of the high-low temperature test box can quickly solve the various problems that occur in the operation of the high-low temperature test box.

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