Key Factors for Refrigeration Oil Selection

Choosing refrigeration oil is much like finding the right partner—compatibility matters more than just initial fit. Due to varying compressor operating conditions and refrigerants, the selection of refrigeration oil must be tailored to specific equipment. Below are the key factors to consider:

Viscosity A critical property: different refrigerants require matching oil viscosity. Excessively high viscosity increases friction power, heat generation and starting torque; overly low viscosity fails to form an effective oil film, compromising lubrication and cooling. Low-viscosity oils are recommended for reduced friction and improved compressor efficiency, though they may cause noise in aging equipment due to insufficient lubrication.

Cloud Point The temperature at which paraffin precipitates and the oil turns cloudy. Must be lower than the refrigerant’s evaporation temperature to avoid throttle valve blockage or impaired heat transfer.

Freezing Point: The temperature at which the oil stops flowing. The lower the better—high freezing points hinder refrigerant flow, increase resistance and reduce heat transfer efficiency. Critical for extreme temperature/pressure lab environments or ultra-low temperature cold storage.

Flash Point: The minimum temperature at which oil vapor ignites on contact with flame. Must be 15–30℃ higher than the compressor’s exhaust temperature to prevent oil combustion and coking.

Other Factors: Including chemical stability, oxidation resistance, water/mechanical impurity content, and insulation performance.