Refrigerator refrigeration system leak detection

Refrigerator refrigeration system leak detection

Refrigerator refrigeration system leak detection

　　 The refrigeration system should be tested for leaks due to refrigerant leakage or refrigerators after replacing parts. The following three methods are generally used for leak detection in refrigeration systems:

(1)Oil leak detection method. Lubricating oil is dissolved in the refrigerant. When the compressor is working, the temperature rises to vaporize part of the lubricating oil. As the refrigerant leaks out, oil stains are formed on the surface of the refrigeration system, which is a sign of refrigerant leakage. When looking for oil stains on the refrigeration system, focus on the welds and welds. Such as the weld on the compressor casing, the weld around the terminal, the high and low pressure pipe weld, the weld on the high pressure exhaust pipe and the condenser, the weld on the condenser and the filter, the weld on the filter and the capillary , The welding port of the capillary tube and the evaporator, the welding port of the evaporator and the low-pressure suction pipe, and the seal of the refrigerant filled pipe on the compressor. If the oil stain is not obvious, you can use clean white cotton or white paper to hold the welding joint, after a while, observe whether there is oil stain on the cotton, if there is oil stain, it means there is leakage. After confirming the leakage, polish with emery cloth for repair welding. Since the oil stains will obviously exist in the leak after the refrigerator has been used for a long time, the method of oil stain leak detection is only suitable for refrigerators that have been used for a period of time.

(2) Suppress leak detection. Pressure leak detection is to charge a certain pressure of gas into the refrigerator refrigeration system to detect leaks. Nitrogen or air can be used for pressure leak detection. Nitrogen is an inert gas, does not contain water, is non-flammable, non-corrosive, and is safe to use. Because the nitrogen pressure in the nitrogen cylinder is very high (usually about 150 kg/cm²), it must be used after being decompressed by a pressure reducer for safety. If nitrogen is not available, compressed air can also be used. In order to prevent the moisture in the air from entering the refrigeration system, a filter drier must be used. The method of suppressing leak detection is: firstly, welding a combination tool at the refrigerant filling pipe port of the hermetic compressor.

　Use a right-angle valve to control the opening and closing of the refrigeration system, and observe the gas pressure of the refrigeration system with a vacuum pressure gauge. Connect the right-angle valve to the nitrogen cylinder through the pipeline, open the right-angle valve, and the compressed gas enters the refrigeration system. When the pressure reaches 10 kg/cm², close the right-angle valve and start leak detection. Use a brush dipped in soapy water to paint all weld joints and suspected leaks in order. Observe carefully, and find that bubbling is a sign of leakage. After the leak is found, release the compressed gas for repair welding, and then pressure the leak detection. Leak detection of the entire refrigeration system is a patient and meticulous work, and it needs to be repeated 2 to 3 times to make the refrigeration system airtight. Finally, a constant pressure leak test should be performed. The method of constant pressure leak detection is as follows: Fill the refrigeration system with compressed gas, make the pressure of the refrigeration system a certain value (10 kg/cm²), and close the right-angle valve. After an interval of 12 hours, observe the pressure of the refrigeration system and there should be no significant change. If the pressure drops, there are still small leaks in the refrigeration system and should be leak tested. If the temperature of the compressed gas charged into the refrigeration system is high, it is normal for the pressure to drop slightly after 12 hours. This is the pressure change caused by the gas expansion and contraction, not caused by leakage. Pressure leak detection or constant pressure leak detection can also be used for single component (compressor, steamer, condenser) leak detection. Repair welding must be carried out without pressure in the refrigeration system.

(3) Leak detection with halogen leak detection lamp. Using the feature that the red flame of the halogen leak detection lamp will change its color when it touches the freon gas, you can find the place where freon leaks. Depending on the degree of Freon leakage, the flame color of the leak detection lamp will change differently. When the concentration of freon is small, the flame becomes greenish. As the concentration of freon increases, the flame becomes green, dark green, and purple-green. Because the specific gravity of Freon is larger than that of air, it often leaks above the flame. Halogen leak detection lamps can only check the approximate location where the leak is found. The exact and specific leak location must be determined by applying soapy water. In addition, when using halogen leak detection lamps to detect leaks, there should be no Freon gas in the surrounding air, so as not to affect the accuracy of leak detection.

When using the pressure leak detection method to detect leaks, you can also fill the refrigeration system with 0.5 kg/cm² of freon, and then fill it with compressed gas to make the refrigeration system pressure 10 kg/cm², and then use the leak detection lamp to detect the leak.