There are two kinds of refrigeration methods for high and low temperature test chambers. One is liquid nitrogen refrigeration, which is usually used in cryogenic low temperature chambers (such as when the temperature is -100 ℃, -200 ℃ or even extreme low temperature), and the other is mechanical refrigeration. Compressor cooling, this cooling method is widely used in the environmental test equipment industry. In this article, how to solve the problem of high and low temperature test chambers that do not cool down and slow down is a solution for mechanical refrigeration.
When there is no temperature drop in the high and low temperature test chamber, the ambient temperature should be reduced to between 5 ℃ ~ 28 ℃, and then check whether the air-cooled condenser is due to the long use time and the accumulation of dust is too thick. It is enough to clean the dust on the condenser (you can use a compressed air gun to purge). If the surface of the condenser is very clean or a new machine, you should look at the reading of the refrigeration pressure gauge. The static pressure is generally 6 kg (or 90psi, the innermost circle of the pressure gauge), the pressure in the shutdown state is as shown in the specified position in Figure 3 (the black line is drawn on the pressure gauge as a mark when leaving the factory), if it is below, there may be refrigerant leakage, resulting in insufficient cooling capacity, If the refrigeration system needs to be repaired, please contact the after-sales service department of the manufacturer in a timely manner 021-60509999.
If it is judged that it is not the cause of refrigerant leakage, then use a multimeter to measure whether the solid-state relay has broken down (the pins 1 and 2 of the load end break down and are completely connected), which causes the heating tube to work all the time, which offsets the cooling of the compressor. Cooling. There is another possibility that the cooling solenoid valve is not opened, or the coil is damaged. Use a multimeter to measure the resistance of the solenoid coil. Under normal circumstances, the resistance is about 1000 ohms. If there is no resistance, it means an open circuit. If the value is too small, there may be a short circuit;
Attachment: Solution for slow cooling of high and low temperature test chamber
1. The thermal load of the studio is too large, the fan does not turn, and the door is not closed properly (air leakage)
2. Breakdown of some solid-state relays (such as heating 2 solid-state relays and 1 breakdown) causes a portion of the heating tubes to heat up, which cancels out part of the cooling capacity, resulting in the illusion of slow cooling.
3. There are too many test articles stacked in the test box (normally not more than one-third of the total volume of the inner box), resulting in the wind being unable to circulate and the temperature fluctuating.
How to solve the problem that the high and low temperature test chamber does not cool down or slow down?
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