How to deal with dehydration of lubricating oil filter?

Lubricating oil filter dehydration is a key step in removing water from the oil. The specific method must be selected based on the water content and type of equipment. The following are common treatment solutions and precautions:

Common dehydration methods

1. Vacuum dehydration method

- Principle: Use a vacuum pump to reduce the system pressure so that the water boils and evaporates at a low temperature.

- Applicable scenarios: medium and high water content (such as free water or emulsified water).

- Key points of operation:

- The vacuum degree is usually maintained at -0.08～-0.095 MPa, and the temperature is controlled at 60～70℃ (to avoid oil oxidation).

- Use a coalescing separation filter element or a molecular sieve to enhance the dehydration effect.

2. Coalescing separation method

- Principle: Coalesce tiny water droplets through hydrophilic materials, and then separate them by gravity or centrifugal force.

- Applicable scenarios: emulsified water or trace water (such as turbine oil, hydraulic oil).

- Equipment requirements: Two-stage filtration with a coalescing filter element and a hydrophobic filter element is required.

3. Centrifugal separation method

- Principle: Use centrifugal force to separate water (density is greater than oil).

- Applicable scenarios: large amounts of free water or heavily contaminated oil (such as gear oil).

4. Adsorption dehydration method

- Materials: silica gel, molecular sieve, or activated alumina.

- Applicable scenarios: trace amounts of water (such as insulating oil need to be reduced to ppm level.

Note: The adsorbent must be replaced or regenerated regularly.

5. Heating sedimentation method

- Simple operation: Heat the oil to 50-60℃ and let it stand for 24 hours, then drain the bottom.

- Limitations: Only applicable to free water, low efficiency.

Operation process example (taking vacuum oil filter as an example)

1. Pretreatment

- Detect the moisture content (such as the Karl Fischer method or visual inspection).

- If there is a large amount of free water, start sedimentation or centrifugal separation first.

2. System startup

- Turn on the heater (temperature ≤65℃) to avoid local overheating.

- Start the vacuum pump and gradually increase the vacuum degree to the target value.

3. Circulation filtration

- The oil circulation time is usually 4 to 8 hours (depending on the moisture content).

- Monitor the outlet oil sample until the moisture content meets the standard (such as ≤ 50 ppm).

4. Post-processing

- Turn off the heater and continue to vacuum for 30 minutes to cool the oil.

- Drain the condensed water from the equipment.

Precautions

1. Safety risks

- Fire prevention is required during high-temperature operation, and the vacuum system should be prevented from leaking.

- Some additives (such as ZDDP) may decompose due to high temperature, and the oil tolerance needs to be confirmed.

2. Oil compatibility

- Silica gel or molecular sieve may adsorb additives, and inert materials are preferred.

3. Efficiency optimization

- When the moisture content is high, mechanical dehydration (such as centrifugation) can be performed first and then vacuum treatment.

- Regularly maintain the filter element and vacuum pump oil to avoid secondary contamination.

4. Environmental protection requirements

- The collected wastewater must be treated according to environmental protection standards to avoid direct discharge.

Dehydration standard reference

- Industrial lubricating oil: moisture ≤ 0.05% (500ppm)

- Transformer oil: moisture ≤ 10-20ppm (depending on voltage level)

If the moisture content still exceeds the standard after treatment, it is necessary to check the equipment sealing, filter element status, or extend the treatment time. For stubborn emulsified oil, consider adding demulsifier to assist treatment (compatibility needs to be verified).