Lubricating oil purification temperature range reference

The purification temperature range of lubricating oil needs to be determined comprehensively according to the oil type, purification equipment and target pollutants (water, impurities, gas, etc.). The following are typical temperature ranges and precautions corresponding to different purification technologies:

1. Vacuum oil filter (dehydration/degassing)

- Temperature range: 50~70℃ (60℃ is commonly used)

- Reasons:

- Temperature is too low (<50℃): low water evaporation efficiency and poor vacuum degassing effect.

- Temperature is too high (>70℃): may accelerate oil oxidation and destroy additives (such as antioxidants).

- Special oil adjustment:

- Synthetic ester oil: ≤65℃ is recommended (high temperature is easy to hydrolyze).

- High viscosity oil (such as ISO VG 460): can be raised to 70~75℃ to reduce viscosity.

2. Pressure oil filter (plate and frame)

- Temperature range: 40~60℃

- Reason:

- Too high a temperature will reduce the mechanical strength of the filter paper and cause it to break.

- Too low temperature (such as <30℃) will affect the filtration speed due to high viscosity.

3. Centrifugal oil filter

- Temperature range: 50~65℃

- Reason:

- It is necessary to maintain the fluidity of the oil (reduce viscosity), but too high a temperature will reduce the centrifugal separation efficiency (reduce density difference).

4. Adsorption oil filter (silica gel/molecular sieve)

- Temperature range: 30~50℃

- Reason:

- High temperature (>50℃) will reduce the adsorption capacity of the adsorbent (such as silica gel) for water.

- Low temperature (<30℃) may affect the speed of oil passing through the adsorption bed.

5. Electrostatic oil filter

- Temperature range: 20~50℃

- Reason:

- High temperature may interfere with the stability of the electrostatic field and increase the risk of oil oxidation.

General precautions

1. Oil characteristics priority:

- Mineral oil: high temperature resistance (up to 80℃, but recommended ≤70℃).

- Synthetic oil (such as PAO, ester): must strictly follow the manufacturer's recommendations (usually ≤65℃).

2. Safety restrictions:

- Flash point requirements: The purification temperature must be at least 20℃ lower than the oil flash point (such as oil with a flash point of 200℃, the temperature must be ≤180℃).

3. Oxidation control:

- If long-term heating is required (such as >8 hours), it is recommended to be carried out under nitrogen protection.

4. Viscosity matching:

- High viscosity oil (such as gear oil) can increase the temperature appropriately, but the acid value changes need to be monitored.

Typical standard references

- ISO 4406: The particle level after purification is recommended to reach ≤15/12/9 (NAS level 6).

- Water requirements:

- Industrial gear oil: ≤500ppm (general purpose) or ≤100ppm (precision equipment).

- Turbine oil: ≤100ppm (ISO 6743-5).

It is recommended to adjust the temperature parameters according to the technical manual of the specific oil and the guidance of the equipment manufacturer.