Causes of Oil Blockage in Thermal Shock Test Chambers

During the transportation of thermal shock test chambers, technicians often remind to keep the equipment as level as possible; otherwise, oil blockage may occur. What exactly causes oil blockage in these chambers? And how should we resolve it if it happens?

If the thermal shock test chamber is tilted at a significant angle during operation, the refrigeration oil inside the compressor will flow from the suction pipe into the low-pressure chamber. When the compressor is restarted for cooling, the refrigeration oil gets drawn into the cylinder, which can temporarily increase the compressor’s load (the compression ratio in the cylinder is determined by gas volume, but liquid is not easily compressible). More importantly, when the refrigeration oil is delivered to the condenser and then passes through the drying filter into the narrower capillary tube, pipeline blockage occurs—this is commonly referred to as “oil blockage.”
How to Resolve Oil Blockage in Thermal Shock Test Chambers
In repairing the test chamber, first cut off the process pipeline, release the refrigerant, connect the service gauge valve, and weld off the drying filter. Then, begin nitrogen charging through the gauge valve; after charging nitrogen, airflow will emerge from the capillary tube end connected to the drying filter. Maintain this airflow for approximately one minute to eliminate the frozen oil that has entered the capillary tube. Next, intermittently release the thumb sealing the condenser pipe opening three to five times, for about ten seconds each time, allowing the frozen oil within the condenser pipe to flow out. Subsequently, release the capillary tube and close the service valve.
Through the above procedures, the oil-blocked pipeline is essentially cleared. To ensure the blockage is thoroughly removed, the nitrogen charging process may be repeated. Install a new drying filter, evacuate the system, and then inject refrigerant; the heating and cooling functions of the test chamber equipment should return to normal operation. This is the method for handling oil blockage in test chamber equipment. After resolving the oil blockage, operators must inspect the equipment components to confirm they are intact before the test chamber can be put back into normal service.