Can the vacuum oil filter remove water?

A vacuum oil filter is one of the equipment specially designed for the efficient removal of water from oil, especially suitable for the dehydration of industrial oils such as lubricating oil, transformer oil, turbine oil, etc. Its dehydration principle and effect are as follows:

Principle of dehydration by vacuum oil filter

1. Heating viscosity reduction

- The oil first passes through the heater (usually heated to 60~70℃, the specific temperature is adjusted according to the flash point of the oil) to reduce the viscosity of the oil, making the water easier to evaporate and breaking the oil-water emulsification state.

2. Vacuum flash separation

- The heated oil enters the vacuum separation chamber (the vacuum degree is usually maintained at -0.08~-0.095 MPa), under low low-pressure environment:

- Free water and dissolved water in the oil are rapidly vaporized (the boiling point of water decreases with the decrease of pressure, such as the boiling point of about 45℃ at -0.09 MPa).

Water and volatile gases escape from the oil to form water vapor.

3. Condensation drainage

- Water vapor is pumped to the condenser by the vacuum pump, condensed into liquid water after cooling, and discharged automatically or manually through the drain valve.

- The dried oil continues to flow to the downstream fine filtration system.

4. Precision filtration (optional)

- The dehydrated oil may pass through a coalescing filter element or a particle filter to further intercept residual trace water or solid impurities.

Water removal capacity of the vacuum oil filter

- Types of water that can be treated:

- Free water (suspended large water droplets) → Efficient removal (more than 99%).

- Dissolved water (molecularly dispersed in oil) → Can be reduced to less than 10 ppm by vacuum evaporation (such as transformer oil requires a water content of ≤15 ppm).

- Emulsified water (oil and water mixed into an emulsion) → Demulsification technology is required (such as heating + vacuum + coalescence).

- Treatment effect:

- The water content of the oil after typical dehydration can reach ≤50 ppm (depending on the initial water content and equipment performance).

- For insulating oil (such as transformer oil), it can meet the IEC 60422 or GB/T 7600 standards.

Applicable oils and scenarios

1. Transformer oil: Remove moisture to improve insulation strength (such as breakdown voltage ≥60 kV).

2. Turbine oil (steam turbine oil): Prevent moisture from causing surface rust or oil film rupture.

3. Hydraulic oil: Avoid moisture from causing valve jamming or additive hydrolysis.

4. Lubricating oil regeneration: Dehydration of waste oil prolongs service life.

Vacuum oil filter vs other dehydration methods

| Dehydration method | Advantages | Limitations |

|--------------------|-----------------------------------|-------------------------------|

| Vacuum oil filter | Deep dehydration (can handle dissolved water), no pollution | High equipment cost, slow processing speed |

| Coagulation separation | Quickly remove free water, suitable for online processing | Ineffective for dissolved water, filter element needs to be replaced regularly |

| Centrifugal | No filter material required, suitable for high water content oil | Low precision (cannot handle tiny water droplets) |

| Adsorption | Can remove trace moisture (such as molecular sieve) | The adsorbent needs to be replaced after saturation, and the operating cost is high |

Precautions for use

1. Temperature control:

- The heating temperature must be lower than the flash point of the oil (usually leaving a safety margin of 15~20℃) to avoid oil oxidation or fire risks.

2. Vacuum adjustment:

- Too high a vacuum may cause excessive evaporation of the oil, and the parameters need to be optimized according to the characteristics of the oil.

3. Oil compatibility:

- Some synthetic oils (such as ester oils) may be corrosive to vacuum pump sealing materials and require special design.

4. Maintenance points:

- Regularly clean the vacuum pump oil and check the drainage function of the condenser to prevent system contamination.

The vacuum oil filter is one of the most thorough technologies for dewatering in the industrial field, especially suitable for oils with strict requirements on water content (such as transformer oil and turbine oil). For oils with extremely high water content, free water can be removed by centrifugal or coalescence pretreatment, and then combined with vacuum dehydration to improve efficiency. When selecting, the equipment parameters need to be matched according to the oil type, initial water content and target standard (such as ISO 4406, NAS grade).