Total Oil Classes
Oil in compressed air can contaminate products, damage sensitive equipment, and create safety hazards. ISO 8573-1 defines 5 classes (0-4) based on total oil concentration.
Classification Table
| Class | Maximum oil concentration |
|---|---|
| 0 | Per user specification |
| 1 | ≤ 0.01 mg/m³ |
| 2 | ≤ 0.1 mg/m³ |
| 3 | ≤ 1 mg/m³ |
| 4 | ≤ 5 mg/m³ |
Total Oil
Includes oil in liquid, aerosol AND vapor form. Coalescing filters alone are not enough; Class 1 requires activated carbon.
Interpretation
- Class 0: Special requirements defined by the user
- Class 1: Technically oil-free air, for pharmaceutical and food
- Class 2: Very clean air, for electronics and painting
- Class 3: Clean air, for demanding industrial applications
- Class 4: General quality for pneumatic tools
How to Achieve Each Class
| Class | Equipment needed |
|---|---|
| 1 | Coalescing filter + Activated carbon filter |
| 2 | High-efficiency coalescing filter |
| 3-4 | Standard coalescing filter |
Lubricated compressors
Lubricated compressors always introduce oil into the air. For Class 1 applications, consider oil-free compressors or comprehensive treatment.