The high and low temperature test chamber is generally composed of a compressor, an evaporator, a condenser and a piping system. There are two types of clogging in the refrigeration system: dirty plugging and ice blocking. Oil plugging is relatively rare.
1, dirty plug
The high and low temperature test chamber compressors wear out. When there is dirt in the refrigeration system, these dirt are easily blocked in the capillary or the filter, which is called dirty plugging. Dirty plugging is caused by impurities (scale, copper scrap, slag) in the refrigeration system, and clogging at the capillary or filter as it circulates with the refrigerant.
Dirty plug removal method: remove the capillary, filter, condenser, evaporator by gas welding, replace the molecular sieve in the capillary and filter, clean the condenser and evaporator, dry, vacuum, re-weld, charge the refrigerant .
2, ice block
The ice block is caused by the moisture entering the high and low temperature test chamber refrigeration system. Because f-12 itself contains a certain amount of water, combined with the process of evacuation during maintenance or fluorination, the process is not strict, so that moisture and air enter the system. Under the high temperature and high pressure of the compressor, the refrigerant changes from a liquid state to a gaseous state, so that the water circulates into the narrow and long capillary tube with the refrigerant. When the water content per kg of refrigerant exceeds 20 mg, the water of the filter is saturated, and the water cannot be filtered out. When the temperature at the outlet of the capillary reaches 0 ° C, the water is decomposed from the refrigerant to form ice and form an ice block. Dirty blockage and ice blockage are divided into full block and half block. The fault phenomenon is that the evaporator is not frosted or frosted, the temperature of the rear part of the condenser is too high, and the temperature of the filter or capillary inlet is felt by hand. The room temperature is almost equal, sometimes even below room temperature, and the process tube has a large amount of gas to be ejected. After the ice block is formed, the compressor exhaust resistance increases, causing the compressor to overheat, the thermal protector works, and the compressor stops running. After about 25 minutes, the ice block is partially melted, the compressor temperature is lowered, and the thermostat and thermal protector The contacts close and the compressor starts to cool. Therefore, the ice plug has periodicity, and the evaporator can be seen to periodically frost and defrost.
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