Huanyi instrument high and low temperature test chamber cooling failure analysis

As customers often encounter constant temperature and humidity equipment does not cool the situation, so collect multiple common factors, the following comments are for reference only.

Analysis of a: As the temperature is not maintained, observe whether the refrigeration compressor can start during the operation of the test chamber, the compressor can start 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.

No problems with the electrical system, continue to check the refrigeration system. First of all, check the two refrigeration units of low temperature (R23) level compressor exhaust and suction pressure are lower than the normal value, and suction pressure is pumping state, indicating that the main refrigeration unit refrigerant quantity is insufficient. The temperature of the exhaust and suction lines of the R23 compressor of the main unit was not high by hand, and the temperature of the suction line was not low (not frosted), which also indicated the lack of R23 refrigerant of the main unit.

Analysis two: the cause of the failure is not determined, combined with the control process of the test chamber to further confirm the cause of the failure, the test chamber has two sets of refrigeration units. One is the main unit, the other is the auxiliary unit, in the cooling rate is larger, the two sets of units work at the same time, in the early stage of temperature maintenance, the two sets of units still work at the same time.

When the temperature is initially stabilized, the auxiliary unit will stop working and the main unit will maintain the temperature stability. If the main unit R23 leaks, it will make the cooling effect of the main unit not big, and because of the cooling process, the two units work at the same time, so there is no phenomenon that the temperature can't be stabilized, and the cooling rate is indicated to be reduced.

In the temperature maintenance stage, once the auxiliary unit stops working and the main unit has no refrigeration effect, the air in the test chamber will rise slowly, and when the temperature rises to a certain level, the control system will start the auxiliary unit to cool down the temperature to the set value (-55 ℃) nearby, and then the auxiliary unit will stop working again, so repeatedly, the failure phenomenon shown in Figure 3 will occur.

So far, it has been confirmed that the cause of the production failure is the refrigerant R23 leakage of the low temperature (R23) level unit of the main unit.

High and low temperature test chamber, constant temperature and humidity test chamber

Leak detection on the refrigeration system, using a combination of leak detector and soap and water inspection, found a hot gas bypass solenoid valve stem cracked about 1cm slit. Replace this solenoid valve, the system re-fluoride, the system operates normally. As can be seen above, the analysis and judgment of the fault phenomenon is basically easy to difficult, first "outside" after "inside", first "electrical" after "refrigeration" vein of analysis and judgment, familiarity and understanding of the principle of the test chamber and the working process is to analyze the fault Judgment of the basis of failure.

According to the above analysis, only in-depth understanding of the working principle of the test chamber and the working process, in order to quickly solve the problems that arise in the operation of the test chamber.