Runhua tells everyone why the constant temperature and humidity box is not cooling

The reason why the constant temperature and humidity box is not cooling

I believe everyone will have no cooling when using the constant temperature and humidity box. Now Runhua will take you to understand the reason why the constant temperature and humidity box is not cooling.
Reason 1:

1. There is no problem with the electrical system, continue to check the refrigeration system. First, check that the discharge and suction pressures of the low-temperature (R23) compressors of the two sets of refrigeration units are lower than normal, and the suction pressure is in an evacuated state, indicating that the main refrigeration unit has insufficient refrigerant quantity.

2. Touch the exhaust and suction pipes of the R23 compressor of the main unit by hand, and found that the temperature of the exhaust pipe is not high, and the temperature of the suction pipe is not low (no frost), which also shows the main unit The R23 refrigerant is lacking.

3. Because the temperature cannot be maintained, observe whether the refrigeration compressor can be started during the operation of the test chamber, and the compressor can be started during the operation of the environmental test equipment, indicating that the electrical wiring from the main power supply to each compressor is normal. There is no problem with the system.

Reason two:

1. The cause of the failure has not been determined, and the cause of the failure is further confirmed in conjunction with the control process of the test box. The test box has two sets of refrigeration units.

2. One is the main unit and the other is the auxiliary unit. When the cooling rate is high, the two groups of units work at the same time. At the beginning of the temperature maintaining phase, the two groups of units still work at the same time. When the temperature stabilizes initially, the auxiliary unit stops working, and the main unit maintains the temperature stability. If the main engine group R23 leaks, the cooling effect of the main engine group will not be great. Since the two units work at the same time during the cooling process, there is no phenomenon that the temperature is unstable, and the indicated cooling rate is reduced. In the temperature holding phase, once the auxiliary unit stops working and the main unit has no cooling effect, the air in the test chamber will rise slowly. When the temperature rises to a certain level, the control system will start the auxiliary unit to cool down and reduce the temperature to the set point. Near the fixed value (-55℃), and then the auxiliary unit stops working again. If this is repeated, malfunctions will occur. So far, the cause of the production failure is the leakage of refrigerant R23 in the low-temperature (R23)-class unit of the main group. The refrigeration system was checked for leaks, and a leak detector was used in conjunction with soapy water. It was found that the stem of a hot gas bypass solenoid valve had a crack of about 1 cm. Replace the solenoid valve, refill the system with fluorine, and the system runs normally. As can be seen from the above, the analysis and judgment of this fault phenomenon is basically easy to difficult. First, "outside" and then "in", first "electrical" and then "refrigeration" to analyze and judge the context. Understanding the principle and working process of the test chamber is the basis for analyzing and judging failures.