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Time：2025-04-02 11:41:39 Reading volume：
After professional filtration and purification, lubricating oil can usually continue to be used, but whether it can be reused depends on the degree of oil contamination, purification technology, oil performance indicators and equipment requirements. The following is a specific analysis:
1. Whether the pollutants are completely removed
- Solid particles: After filtration, the cleanliness level required by the equipment must be achieved (such as ISO 4406 ≤15/13/10 or NAS ≤6).
- Moisture: The water content should be lower than the critical value (such as hydraulic oil ≤500 ppm, transformer oil ≤15 ppm).
- Oxidation products: sludge, colloid, etc. need to be removed by adsorption or centrifugal separation.
2. Whether the key performance of the oil meets the standard
- Viscosity: The change range is ≤±10% (compared with new oil).
- Acid value (TAN): ≤0.5 mg KOH/g (too high indicates severe oxidation).
- Additive content: Spectral analysis is used to detect whether additives such as zinc and phosphorus are exhausted.
- Flash point: If it is significantly reduced (e.g., it drops by more than 20°C), it may be mixed with light pollutants and needs to be scrapped.
3. Equipment requirements
- High-precision equipment (such as aircraft engines and CNC machine tools) may be required to use new oil, and reuse is not allowed even if it meets the standards after purification.
- Ordinary industrial equipment (such as gearboxes and hydraulic stations) is usually allowed to use purified oil.
| Purification method | Recoverable performance | Limitations | Applicable scenarios |
|--------------------|-------------------------------|-------------------------------|---------------------------|
| Vacuum dehydration | Water, dissolved gas | Cannot repair additive loss | Transformer oil, turbine oil |
| Precision filtration | Solid particles (1~30μm) | Does not solve oxidation or moisture problems | Hydraulic oil, gear oil |
| Centrifugal separation | Free water, large particle impurities | Ineffective for tiny particles (<5μm) | Pretreatment of waste oil with high water content |
| Adsorption treatment | Colloid, acidic substances, pigments | Adsorbent needs to be replaced after saturation, high cost | Regenerated waste lubricating oil |
| Electrostatic purification | Submicron particles, colloids | Need to cooperate with other technologies for dehydration | Precision machinery oil |
3. Risks and precautions for the reuse of lubricating oil after purification
1. Risks
- Additive depletion: Purification may not be able to replenish the consumed antioxidants, extreme pressure agents, etc., resulting in a decrease in lubrication performance.
- Residual contaminants: Tiny particles or moisture that are not completely removed may accelerate equipment wear.
- Oil compatibility: Mixing purified oils of different brands/models may cause chemical reactions (such as precipitation).
2. Precautions
- Oil testing: Key indicators (such as viscosity, moisture, and particle count) must be tested after purification and compared with the equipment manufacturer's standards.
- Use in stages: Purified oil can be used preferentially for secondary equipment or low-load conditions.
- Avoid mixing: Different batches of purified oil must ensure consistent composition before mixing.
Even after purification, the lubricating oil should be scrapped in the following situations:
1. Severe oxidation: The oil is black and viscous, and the acid value is greater than 1.0 mg KOH/g.
2. Additive failure: Spectral analysis shows that the content of key additives such as zinc and phosphorus is less than 50% of the new oil.
3. Irreversible pollution, such as mixing with fuel oil, coolant or heavy metal pollutants.
| Solution | Cost | Environmental protection | Recommended scenario |
|-------------------|-----------------------------|--------------------------|-------------------------|
| Reuse after purification | About 20%~50% of the cost of new oil | Reduce waste oil emissions | Medium and low pollution oil, non-precision equipment |
| Direct replacement of new oil | 100% new oil cost + waste oil treatment fee | Waste oil generated | High-demand equipment or oil products scrapped |
1. Power plant turbine oil: Through vacuum oil filter dehydration + precision filtration, the oil change cycle can be extended to 5~8 years (regular addition of additives).
2. Engineering machinery hydraulic oil: Centrifugal + coalescence purification and reuse, saving 30% of lubrication costs.
3. Waste oil recycling plant: Adsorption + distillation process is used to purify waste oil to a standard close to new oil (additives are required).
Whether the lubricating oil can be used after filtration and purification needs to be judged by data. If the key indicators are qualified and the equipment allows, reuse can significantly reduce costs; otherwise, new oil needs to be replaced. It is recommended to combine oil testing + equipment operating conditions to make scientific decisions to avoid small losses.
