Refrigeration common fault terms and operation precautions

Refrigeration common fault terms and operation precautions

Frozen blocking: also known as "ice blocking". The phenomenon in which liquid freezing substances [such as ice] hinder the flow of refrigerant in the Freon refrigeration system. Often occurs in throttling mechanisms. When the water content of the refrigerant exceeds the specified standard, the temperature drops due to the throttling and decompression when flowing through the throttling mechanism. The mixed water and moisture in the free state may form ice at the throttling part or completely block the throttle valve hole or Capillary channel. As a result, the Freon flow rate in the system decreases sharply, the suction and exhaust pressures drop, and the refrigeration capacity drops. Even the Freon cannot pass through and the refrigeration device cannot work normally. The judgment method is to heat with fire outside the throttle mechanism. If the above phenomenon can be eliminated after heating, it is freezing blockage, otherwise it is dirty blockage.

Dirty blockage: The phenomenon that the refrigerant pipeline, valve or filter screen of the refrigeration system is blocked by dirt and hinders the flow of refrigerant. The refrigerant flow rate in the system is reduced, the cooling capacity is reduced, and there is even no cooling effect. The clogged parts must be removed for cleaning, and the system can be debugged after installation.

Oil clogging: The expansion valve hole of the Freon refrigeration device is blocked by solidified lubricating oil and hinders the flow of refrigerant. Occurs in low-temperature equipment below -60 degrees Celsius, where lubricating oil with high freezing point and soluble in Freon is used. At this time, the Freon liquid flowing through the expansion valve hole causes part of the lubricating oil to precipitate and freeze into a thick paste due to the sudden drop in temperature, and the valve hole is blocked. The elimination method is to exchange suitable lubricating oil.

Hydraulic shock: also known as "cylinder flushing", "wet stroke" or "cylinder knocking". Failure caused by refrigerant liquid or lubricating oil, or a mixture of the two liquids entering the compressor cylinder. Since the liquid is not compressible, when the volume of the liquid entering the cylinder is greater than the clearance volume, the compressive force generated by the compressed liquid will damage the valve, cylinder head and other parts, causing accidents.

Copper plating phenomenon: the phenomenon that copper atom deposits are formed on the surface of the valve plate, piston pin, cylinder wall and other parts of the refrigeration compressor. It mostly occurs in semi-hermetic or hermetic compressors. It is a phenomenon that occurs when the compressor has copper parts and is used as a refrigerant and contains moisture. It can cause defects on the surface of the copper parts to shorten the life, and the gap between the running-in surfaces of the moving parts is too small to damage the parts, and the sealing surface can be poorly sealed.

Inverted frost: also known as "back frost". In a piston compression refrigeration system, the refrigerant leaving the evaporator flows into the compressor crankcase through the return line in a liquid state, [this article source: Refrigeration Encyclopedia Public Number], due to heat absorption and gasification, and is outside the return pipe and crankcase The phenomenon of frost. This phenomenon is likely to occur when the refrigerant is overcharged or the liquid supply is too much. In severe cases, it will cause the compressor to strike.

Burned out: short for "refrigeration compressor coil burned out". The phenomenon that the coil is burnt out due to short circuit of the coil or overload of the compressor. After the fault occurs, cut off the power supply in time, and then rewind the burnt coil or replace with a new compressor.

It should be noted that it is generally not recommended to directly replace the refrigeration compressor after it is burned. The following matters should be noted:

1. The cause of damage to the original refrigeration compressor must be checked before replacement, and defective parts must be replaced. Because the damage of other components will directly cause damage to the refrigeration compressor.

2. After removing the original damaged refrigeration compressor, the system must be purged with nitrogen before connecting the new refrigeration compressor system.

3. During welding operation, in order not to form an oxide film on the inner wall of the copper pipe, it is recommended to pass in nitrogen gas, and the time to pass the nitrogen gas should be sufficient.

4. It is forbidden to use the refrigeration compressor as a vacuum pump to evacuate the air in the pipeline of the external machine when replacing the refrigeration compressor or other parts, otherwise the refrigeration compressor will be burned, and a vacuum pump must be used to vacuum.

5. When replacing the refrigeration compressor, it is necessary to add refrigerating oil that meets the nature of the refrigeration compressor, and the amount of refrigerating oil should be appropriate. Generally speaking, the new original compressor has refrigerating oil.

6. When replacing the refrigeration compressor, the filter drier must be replaced in time. Because the desiccant in the filter drier has been saturated, the water filtering function is lost.

7. The refrigerating oil in the original system must be cleaned, because the new pump has been injected with enough refrigerated lubricating oil, different brands of refrigerating oil cannot be mixed, otherwise it will deteriorate and cause poor lubrication, causing the refrigeration compressor to pull the cylinder and turn yellow , Burnt.

8. When replacing the refrigeration compressor, pay attention to prevent excessive refrigerating oil in the system, otherwise it will cause the heat exchange effect of the system to decrease, thereby making the system pressure higher and damaging the system and the refrigeration compressor.

9. Don't fill the refrigerant too fast, otherwise it will cause liquid shock and cause pressure loss in the refrigeration compressor.

10. After installation, check that the compressor is working normally, such as: suction pressure/temperature, discharge pressure/temperature, oil pressure differential pressure and other system parameters. If the parameter exceeds the normal value, the reason for the abnormal system parameter must be clarified.