-150℃ cryogenic equipment needs to know this when performing freezing interference fit!

2020-11-17 14:54:34

　　The temperature limit of cryogenic treatment with freezing interference fit is -100°C. When used below -100°C, the body, bonnet, and seals of various valves should be treated with low temperature, and the low temperature treatment temperature should not be higher than the actual use temperature of the valve.

　　 When the low temperature time is extended from 30min to 70h, there is no obvious regular change in the deformation and martensitic transformation of the sample, which basically shows the characteristics of nucleation and rapid growth in a short time.

　　 To ensure sufficient and balanced cryogenic treatment, 2h is selected. When the holding time is 2h, the number of cryogenic treatments increases from one to eight, and the deformation of the sample and the martensite phase variable increase irregularly.

Frozen interference fit

　　-150℃ cryogenic equipment, what are the points to note when performing freezing interference fit?

　　 1. The flash point is high enough: the flash point of the lubricating oil should be 20-30℃ higher than the compressor discharge temperature to prevent the lubricating oil from decomposing and coking, deteriorating lubricating performance and sealing performance.

　　2. In the low temperature equipment at -150℃, the viscosity of the compressor lubricating oil decreases with the increase of temperature and increases with the increase of pressure. Different refrigerants should use lubricating oils with different viscosities. If the working temperature of the refrigeration system is low, lubricating oil with low viscosity should be used; if the working temperature of the refrigeration system is high, lubricating oil with high viscosity should be used. High-speed rotary compressors should use high-viscosity lubricants.

3. Good chemical stability: -150℃ low temperature equipment lubricating oil in a system coexisting with refrigerants and metals, if the temperature is high, under the catalysis of the metal, chemical reactions such as decomposition, polymerization, and oxidation will occur, resulting in corrosiveness acid.

　　 4. The cloud point is lower than the evaporation temperature: -150°C. The cloud point of lubricating oil in low-temperature equipment must be lower than the high evaporation temperature in the refrigeration system, because lubricating oil and refrigerant dissolve each other, and flow through the relevant parts of the refrigeration system as the refrigerant circulates. After the lubricating oil precipitates out of paraffin, it will block narrow parts such as the throttle valve hole, or accumulate on the inner surface of the evaporator coil, so that the heat transfer efficiency will be worse.

　　5. Low impurity content: If a small amount of water is mixed into the refrigerant and lubricating oil solution, the acidification of the solution will be accelerated. Copper plating will occur in the refrigeration system of the -150℃ low-temperature equipment, which will reduce the performance of the compressor motor edge. If there are impurities in the lubricating oil, it will accelerate the movement of the lubricated parts.

　　Okay, the editor has said so much about the points to note when performing freezing interference fit with -150℃ cryogenic equipment. I hope the above content will be helpful to everyone.

Nuoruida (Tianjin) science and Technology Co., Ltd. is committed to research, development, and sales of liquid nitrogen freezer. Using European technology, we provide a variety of equipment. The main equipment is liquid nitrogen Cryogenic treatment equipment, cryogenic freezer, liquid nitrogen cabinet freezer, liquid nitrogen tunnel freezer,sub-zero processing equipment, low temperature cold assembly equipment, cryogenic freezing equipment, and so on.