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The reasons why the constant temperature and humidity box is not refrigerated Because customers often encounter the constant temperature and humidity equipment unsolved condition, so today on this issue together to study and explore: Cause one: 1. Because the temperature can not be maintained, observe whether the refrigeration compressor in the test box operation process can be started, the compressor in the environmental test equipment operation process can be started, indicating that from the main power supply to the compressor electrical lines normal, electrical system is not a problem.
2. If there is no problem with the electrical system, continue to check the refrigeration system.
First of all, check that the exhaust and suction pressure of the low temperature (R23) compressor of the two refrigeration units are lower than normal, and the suction pressure is pumped out, indicating that the refrigeration dose of the main refrigeration unit is insufficient.
3. Touch the exhaust and suction lines of the host group R23 compressor by hand and find that the temperature of the exhaust line is not high, and the temperature of the suction line is not low (unfrosted), which also indicates the lack of R23 refrigerant in the host group.
1. The cause of the fault has not been determined, and the fault cause is further confirmed by the control process of the test box, which has two refrigeration units.
2. One is the main unit, the other is the auxiliary unit, when the cooling rate is large, two sets of units work at the same time, in the early stage of temperature hold, the two groups of units are still working at the same time.
the temperature initially stabilized, the auxiliary unit stopped working, by the host group to maintain the stability of the temperature.
if the host group R23 leakage, will make the host group cooling effect is not big, because of the cooling process, the two units work at the same time, so there is no temperature stability phenomenon, and indicates that the cooling rate is reduced.
In the temperature hold phase, once the auxiliary unit stops working, the host group and no cooling effect, the air in the test box will slowly rise, when the temperature rises to the degree, the control system will start the auxiliary unit to cool down, the temperature will drop to the set value (-55 degrees C) near, and then the auxiliary unit stopped working, so repeatedly, there will be a failure as shown in Figure 3.
vortex street flow meter to this point, the production failure has been confirmed as the cause of the host group's low temperature (R23) class unit refrigerant R23 leakage.
the refrigeration system to check for leakage, using a leak detector and soapy water combined method of inspection, found that a hot air bypass solenoid valve stem cracked about 1cm of fine seams.
replace the solenoid valve, refluorine the system, the system is operating normally.
As can be seen above, the analysis and judgment of the phenomenon of the fault is basically easy, first "outside" after "in", first "electrical" and then "refrigeration" of the pulse of analysis and judgment, familiar with and understand the principle of the test box and the working process is the basis for the analysis of fault judgment fault.