1.Viscosity of frozen oil:The frozen oil has a certain viscosity to keep the friction surface of the moving parts in good lubrication state, so that it can take part of the heat from the compressor and play a sealing role.
The oil works at two extreme temperatures:Compressor exhaust valve temperature can be more than 100 degrees, and expansion valve, evaporator temperature will be as low as -40 degrees.If the viscosity of the frozen oil is not enough, it will lead to increased wear and noise of the compressor bearing and cylinder, and at the same time reduce the cooling effect and shorten the service life of the compressor.Even in extreme cases, the compressor may be burned.
2.Pour point of frozen oil:Pour point is also an indicator that may lead to the burning machine.The operating temperature of the compressor has a wide range of variation. Therefore, in order to ensure the function of lubricant can be performed normally, it is generally required to maintain good activity at low temperature.Therefore, the pour point should be lower than the freezing temperature, and the viscosity and temperature should be good, so that the frozen oil can smoothly return to the compressor from the evaporator in the low temperature environment.If the pour point of frozen oil is too high, It will cause the oil to come back too slowly that very easy occurrence machine burned.
3.Flash point of frozen oil:There is also a danger that the flash point of the frozen oil is too low.Because of the high volatility, the low flash point will increase the amount of oil in the refrigeration cycle.Increasing wear and tear adds to the cost. What is more serious is the increased risk of combustion during compression and heating, which requires that the flash point of the refrigerated oil is more than 30 degrees higher than the refrigerated exhaust temperature.
4.Chemical stability:The chemical composition of pure frozen oil is stable, does not oxidize, does not corrode metal.If inferior frozen oil contains refrigerant or moisture, it will cause corrosion. When the oil oxidizes, it will produce acid and corrode metal.When frozen oil is at high temperature, there will be coke and powder, if this substance enters the filter and throttle valve easily caused blockage.Enter the compressor and possibly punch through the motor insulation film. That very easy occurrence machine burned.
5.Excessive mechanical impurities and moisture content:Excessive mechanical impurity and moisture content: if frozen oil contains moisture, it will aggravate the chemical change of oil, cause oil deterioration, cause corrosion to metal, and also cause “ice block” at the throttle or expansion valve.The lubricating oil contains mechanical impurities, which will aggravate the wear of the friction surface of the moving parts and cause damage to the compressor.
6..High content of paraffin:When the working temperature of the compressor drops to a certain value, paraffin begins to separate out from the frozen oil, making it turbid.
The freezing oil exhales paraffin and accumulates at the throttle to block the throttle or may accumulate on the evaporator’s heat transfer surface, affecting the heat transfer performance.
How to tell if it is bad frozen oil
The quality of the frozen oil can be judged by the color of the oil.The normal color of mineral frozen oil is transparent and slightly yellowish, if cloudy or color is very deep in the oil, the impurity content and paraffin content are high.The normal color of ester synthetic frozen oil is transparent belt yellow, slightly darker than mineral oil. The higher the kinematic viscosity is, the darker the color is. When the viscosity reaches 220mPa.The color is brilliant yellow with reddish brown.
We can take a clean sheet of white paper, take out a little bit of the frozen oil, drop it on the white paper, and then watch the color of the oil .If the oil drops are light and evenly distributed, that means the frozen oil is of better quality,If dark dots or circles are found on the white paper, the frozen oil has deteriorated or is inferior frozen oil.
Post time: Dec-14-2018
