How to filter hydraulic oil for recycling?

Filtering hydraulic oil for reuse is an important measure to extend the life of the oil, reduce costs and reduce waste. Hydraulic oil will be mixed with pollutants such as water, gas, solid particles and oxidation products during use. Appropriate filtering and purification methods can effectively remove these pollutants and restore the performance of the hydraulic oil. The following are detailed steps and methods for filtering hydraulic oil:

1. Preparation

- Check the oil status:

- Take samples to test the degree of contamination of the hydraulic oil, including water content, solid particle concentration and acid value.

- ｓｅｌｅｃｔ appropriate filtering equipment:

- According to the type and degree of contamination of the hydraulic oil, ｓｅｌｅｃｔ suitable filtering equipment (such as vacuum oil purifier, centrifugal oil purifier, pressure oil purifier, etc.).

- Prepare tools and materials:

- Filter element, filter paper, adsorbent, heater, oil storage tank, etc.

2. Filtration steps

(1) Preliminary filtration

- Purpose: Remove large solid impurities.

- Method:

- Use a coarse filter or filter (filter accuracy is generally above 25 microns) to perform preliminary filtration on the hydraulic oil.

- Equipment:

- Plate and frame oil purifier or simple filtration device.

(2) Heating dehydration

- Purpose: Remove moisture from the hydraulic oil.

- Method:

- Heat the hydraulic oil to 50°C-70°C to reduce the viscosity of the oil and facilitate the evaporation of moisture.

- Use a vacuum oil purifier to evaporate and separate moisture under a vacuum environment.

- Equipment:

- Vacuum oil purifier.

(3) Fine filtration

- Purpose: Remove tiny solid particles.

- Method:

- Use a high-precision filter element (filter accuracy is 1 micron to 10 microns) to perform fine filtration on the hydraulic oil.

- Equipment:

- Pressure oil purifier or centrifugal oil purifier.

(4) Adsorption purification

- Purpose: Remove oxidation products, colloids and acidic substances in the oil.

- Method:

- Use adsorbents (such as activated alumina, silica gel, molecular sieves) to absorb harmful substances in the oil.

- Equipment:

- Adsorption tower or online adsorption device.

(5) Degassing treatment

- Purpose: Remove dissolved gases in the oil.

- Method:

- Remove air and other gases from the oil through a degassing device under vacuum.

- Equipment:

- Vacuum oil purifier.

3. Testing and evaluation

- Test items:

- Cleanliness (ISO 4406 standard).

- Moisture content (ASTM D6304 standard).

- Acid value (ASTM D664 standard).

- Viscosity (ASTM D445 standard).

- Evaluation criteria:

- Ensure that the filtered hydraulic oil meets the use requirements of the equipment manufacturer.

4. Storage and use

- Storage:

- Store the filtered hydraulic oil in a clean, dry container to avoid contamination.

- Use:

- Re-inject the purified hydraulic oil into the hydraulic system and monitor the oil status regularly.

Common filtration equipment

1. Vacuum oil purifier:

- Suitable for removing moisture and gas.

2. Pressure oil purifier:

- Suitable for high-precision filtering of solid particles.

3. Centrifugal oil purifier:

- Suitable for separating moisture and solid impurities.

4. Coalescing separator:

- Suitable for removing emulsified water.

5. Adsorption device:

- Suitable for removing oxidation products and acidic substances.

Precautions

1. Safe operation:

- Pay attention to high temperature and electrical equipment safety during filtration.

2. Environmental protection requirements:

- Comply with environmental regulations when handling waste oil and wastewater.

3. Regular maintenance:

- Regularly ｒｅｐｌａｃｅ filter elements and adsorbents to ensure filtration results.

4. Oil compatibility:

- Ensure that the filtered hydraulic oil is compatible with the equipment material.

Through the above methods, hydraulic oil can be effectively filtered and made to meet the standards for reuse, thereby reducing operating costs and reducing environmental pollution.