Best Methods for Filtering Industrial Oils: Selection Guide

Choosing the best industrial oil filtration method for lubricating oil, hydraulic oil, turbine oil, or transformer oil depends on contamination type, operating conditions, and budget. This guide outlines high-efficiency oil filtration technologies and how to ｓｅｌｅｃｔ the optimal solution.

Core Objectives of Industrial Oil Filtration

• Remove contaminants: Solid particles, moisture, air, colloids, oxidation byproducts, and acids

• Extend oil life: Restore oil performance and ensure reliable equipment operation

Main Industrial Oil Filtration Technologies

1. Physical Filtration (Solid Particles)

Depth Filter Cartridge Filtration

• Accuracy: 1–30 μm

• Applications: Routine lubricating and hydraulic oil maintenance

• Note: Requires regular element replacement

Surface / Absolute Filtration

• Accuracy: 0.1–5 μm

• Applications: High-precision hydraulic systems and turbine oils

• Equipment: Plate-and-frame or membrane filtration systems

2. Dehydration and Degassing (Water & Air)

Vacuum Dehydration

• Function: Removes dissolved and free water under vacuum

• Performance: Moisture <100 ppm (down to 10 ppm for transformer oil)

• Applications: Turbine oil, transformer oil, water-contaminated hydraulic oil

Coalescing Separation

• Function: Separates free and emulsified water

• Performance: Typically <500 ppm

• Applications: Lubricating oil, cutting fluids, diesel fuel

3. Adsorption Purification (Acids & Aging Products)

• Function: Removes acids, colloids, and color using activated clay or silica gel

• Applications: Severely aged or darkened oils

• Note: Possible additive removal; oil testing recommended

4. Electrostatic Oil Purification (Ultra-Fine Contamination)

• Removal range: 0.01–1 μm

• Advantages: No filter elements, low operating cost

• Applications: High-end turbine oils, synthetic and insulating oils

How to Choose the Right Oil Filtration Method

Step 1: Analyze Oil Condition

Key indicators: ISO 4406 particle count, moisture (ppm), acid number (TAN), dielectric strength

• High particles → Physical filtration

• High moisture → Vacuum dehydration or coalescing

• Oil aging/acidity → Adsorption or electrostatic purification

• Multiple issues → Combined filtration system

Step 2: Match Equipment to Application

• Portable systems: Oil filtration carts

• Large or continuous systems: High-flow vacuum oil filters

• Ultra-clean requirements: Electrostatic or membrane filtration

• Cost-focused maintenance: Cartridge-based filters

Step 3: Follow Industry Standards

• Hydraulic oil: ISO 4406 ≤ 15/13/10

• Turbine oil: Moisture <200 ppm, ISO ≤ 14/12

• Transformer oil: Breakdown voltage >40 kV, moisture <15 ppm

Recommended Multi-Stage Filtration Process

For moderate to heavy contamination, a combined approach delivers the best results:

1. Coarse filtration (~50 μm)

2. Vacuum dehydration + fine filtration (1–5 μm)

3. Optional adsorption or electrostatic purification

Typical solution: Integrated vacuum oil filtration system

Operation, Maintenance, and Cost Benefits

• Online filtration: Enables purification without shutdown

• Oil analysis: Every 3–6 months

• Temperature control: ≤65 °C to prevent oxidation

Economic advantage:
Oil filtration typically costs 20–50% of oil replacement and can extend equipment life by over three times.

Quick Reference: Best Filtration Method by Contamination Type

Final Recommendation

For best results, work with a professional oil testing laboratory or experienced oil filtration equipment supplier to design a solution based on oil analysis data.