Selection and mixing taboos of POE refrigeration oil for cold storage | Practical points for viscosity grade, oil return, and compatibility
Semi enclosed low-temperature piston and variable frequency refrigeration compressors commonly use POE synthetic refrigeration oil, which relies on polarity characteristics and HFC refrigerant solubility, and is brought back to the compressor crankcase along with the refrigerant circulation.
Low temperature cold storage mainstream POE oil viscosity: 40 ℃ kinematic viscosity 68 # is the most widely used, and 100 # is selected for quick freezing and deep freezing conditions; 32 # and 46 # POE oil can be used for medium and high temperature preservation conditions.
Xiteluo is filled with corresponding POE oil according to the refrigerant and model matching at the factory. R404A and R507 low-temperature units are equipped with 68 # POE as standard, and different grades and viscosities of POE are not allowed to be directly mixed.
POE oil has strong moisture absorption. After being exposed to air for more than 15 minutes after opening the cover, it will quickly absorb water. The oil that absorbs water is easily hydrolyzed and acidified, which is the main cause of corrosion in motor windings.
Many maintenance technicians try to save time by mixing mineral oil and PVE oil into POE systems, which leads to the failure of oil refrigerant compatibility, oil precipitation sticking to the walls of heat exchange tubes, and a sharp drop in heat exchange efficiency.
The difficulty of oil return is greater under low evaporation temperature conditions, and the lower the viscosity of POE oil, the poorer its low-temperature fluidity. Blindly selecting high-grade oil products will exacerbate the problem of oil accumulation in the evaporator.
The oil level of the oil separation drum and crankcase sight glass should be controlled within the range of 1/2 to 2/3; If the oil level is too low and the lubrication is insufficient to pull the cylinder, if the oil level is too high, it is easy to cause oil hammer and impact the valve plate.
Foreign trade export unit spare parts package, matched with original POE refrigeration oil of the same model, and labeled with storage requirements: sealed storage, away from light and dry. Long term storage is prohibited in overseas high-temperature warehouses.
Sampling and testing of oil products is a long-term maintenance method. If the acid value is greater than 0.1mgKOH/g and the moisture content is greater than 50ppm, it is recommended to change the oil directly and not continue to operate with problems.
The oil logic for POE in screw compressors is different from that of piston compressors, as high-speed rotors require higher load-bearing capacity. For screw compressors with the same cooling capacity, higher viscosity grades of refrigeration oil are usually used.
Implant 10 popular search keywords: POE refrigeration oil, semi closed piston compressor, R404A compressor, R507 compressor, screw refrigeration compressor, compressor return oil, compressor refrigeration oil model, refrigeration maintenance company, compression condensing unit, cold storage compressor selection
FAQ
1. What is the viscosity of POE refrigeration oil most commonly used in low-temperature cold storage? The mainstream is 68 # POE refrigerant oil.
2. How long does POE oil take to absorb water and deteriorate when exposed to air? Open the lid and expose it for no more than 15 minutes.
Can POE oil be mixed with mineral refrigeration oil? Mixing is strictly prohibited as it may cause oil phase separation.
4. What is the standard oil level control range for the crankcase? Maintain the position of the sight glass at 1/2 to 2/3.
5. Which indicators of oil products must be replaced if they exceed the standard? Acid value>0.1mgKOH/g, moisture content>50ppm.
6. Which grade of POE oil is generally selected for frozen and cryogenic models? Choose more 100 # POE oil.
What are the requirements for storing frozen oil? Store in a sealed, dark, and dry environment.
