Why does refrigerating oil deteriorate How to judge whether the refrigerant oil has deteriorated

Why does refrigerating oil deteriorate How to judge whether the refrigerant oil has deteriorated

How to choose refrigerating oil 1.Why does refrigerating oil deteriorate?

First of all, we must be clear why the refrigeration oil deteriorates.

　　The main reason for deterioration:

　　(1) Water mixed in: As the air infiltrates into the refrigeration system, the water in the air is mixed with the refrigerating machine oil after contacting it; when the refrigerant contains more water, the water will also be mixed into the refrigerating machine oil. When water is mixed into refrigerating machine oil, the viscosity will decrease, causing corrosion to metals. In the Freon refrigeration system, it will also cause "ice jam" phenomenon;

(2) Oxidation: During the use of refrigerating oil, when the compressor discharge temperature is high, it may cause oxidative deterioration, especially refrigerating oil with poor chemical stability, which is more prone to deterioration. After a period of time, the refrigerating oil will be A residue is formed, which deteriorates the lubrication of bearings and other places. Organic fillers, mechanical impurities, etc. mixed into the refrigerating oil will also accelerate its aging or oxidation; 　　

(3) When the refrigerating oil is mixed with several different brands of refrigerating machine oil, the viscosity of the refrigerating machine oil will decrease, and even the formation of the oil film will be destroyed, and the bearing will be damaged; if the two kinds of refrigerating machine oils contain different properties of antioxidant Additives, when mixed together, may produce chemical changes and form sediments, which will affect the lubrication of the compressor, so be careful when using them.

　　(4) There are impurities in the refrigerating oil.

　　How to judge whether the freezing oil has deteriorated?

　　 High-quality refrigerated lubricants are very pure, light yellow in color or colorless and transparent liquid.

The color of the refrigerated lubricating oil that has been used in the compressor for a period of time will gradually become darker, and the transparency will gradually become worse, resulting in deterioration. The cooling and lubricating effect of the deteriorated refrigerating oil becomes very poor. Carbides are formed during the process, which can easily cause dirty blockage of the refrigeration system

　　 (1) How to judge whether the refrigerated lubricating oil has deteriorated

　　 1) Paper dropping method. Take a piece of clean white paper, take out a little bit of the refrigerating oil from the compressor casing, and drop it on the white paper. After a while, observe the color of the oil droplets on the white paper. If the oil droplets are light in color and relatively evenly distributed, it means the refrigerated oil The quality is good and you can continue to use it: If you find dark dots or rings on the white paper, it means that the frozen lubricant has deteriorated or contains too much impurities, and you should consider replacing it.

　　 2) Contrast method. Take the unused frozen lubricating oil, pour it into a clean glass test tube or graduated cylinder and let it stand for a period of time, then use it as a standard sample. Then take a little bit of the frozen lubricating oil to be judged from the compressor, and pour it into another container of the same, observe and compare with eyes. If the color and transparency of the frozen lubricating oil taken out of the compressor is similar to that of the standard frozen lubricating oil, it means that there is no deterioration; if the frozen lubricating oil taken out of the compressor is more obvious than the standard frozen lubricating oil The difference is that it turns into orange-red or red-brown mixed corrosion state, indicating that the frozen lubricating oil has deteriorated and can no longer be used. The frozen lubricating oil should be replaced.

　　 2. How to choose refrigerating oil?

　　The refrigeration oil can be selected according to the following aspects: 　

　　1, choose lubricating oil according to the compression type　

　　 There are three types of compressors for refrigerators: piston type, screw type and centrifugal type. The first two types of lubricating oil are in direct contact with the compressed refrigerant, and the mutual influence between lubricating oil and refrigerant must be considered. The lubricating oil used in the centrifugal type is only used to lubricate the rotor bearings, and can also be selected according to the load and speed.　

　　2, choose lubricating oil according to the type of refrigerant

　　 Lubricating oil in direct contact with refrigerant, the mutual influence between the two should be considered. Refrigerants such as Freon can dissolve in mineral oil. Therefore, the viscosity grade of lubricating oil should be one grade higher than that of insoluble refrigerants to prevent lubrication after being diluted. In addition, pay attention to whether a small amount of lubricating oil mixed into the refrigerant will affect the operation of the refrigeration system. The flocculation point of the refrigerating machine oil is a quality index to check whether the lubricating oil mixed in the refrigerant has precipitated wax crystals and blocked the refrigeration system.

　　3. Choose lubricating oil according to the evaporation temperature of the refrigerant　

　　 Generally speaking, for refrigerators with low refrigerant evaporation temperature, refrigerating oil with low freezing point should be selected to prevent the lubricating oil carried by the refrigerant into the refrigeration system from condensing on the throttle valve and evaporator, affecting the refrigeration efficiency. For refrigerators that use ammonia as a refrigerant, the freezing point of the lubricating oil used should be lower than the evaporation temperature. When freon is used as refrigerant, the freezing point of lubricating oil can be slightly higher than the evaporation temperature.

　　 4. Choose refrigerating oil according to the working conditions of the refrigerator