At least as important as the removal of moisture is the removal of dirt and residual oil. This is achieved by classical filtration. The compressed air quality is classified by DIN ISO 8573-1.

ISO 8573-1 Quality classes
Quality classDust particle size (mm)max. concentration (mg/m³)Water max. pressure dew point (°C)Oil max. concentration (mg/m³)
1

 

0,10,1-700,01
2

 

11-400,1
3

 

55-201,0
4

 

158+35,0
5

 

4010+725
6

 

––+10–
Filtration

By filtration, particles and residual oil (liquid) are filtered from the compressed air.

  • Surface filter (dust filter): particles up to 1 µ (separation efficiency: 99.99 %) and residual oil up to 0.5 mg/m³
  • Depth filter (coalescence filter, micro filter): particles up to 0.01 µ (separation efficiency: 99.99999 %) and residual oil up to 0.001 mg/m³

Regular maintenance and replacement of filter elements is essential to ensure proper functioning.

Adsorption

Adsorption is necessary to reduce the oil vapor content of compressed air.

  • Activated carbon filters contain a filter fleece which has been vaporized with activated carbon. When using activated carbon filters, pre-filtration is necessary.
  • Activated carbon adsorbers contain a bed of activated carbon, which allows more oil vapor to be absorbed. They have a significantly longer service life and better adsorption behavior than activated carbon filters. However, a pre- and post-filtration is necessary.
Filter comparison
PrefilterFine filterUltra-fine filterSuperfine filter
Filter materialSinterbronze, Phase fleecePhase fleecePhase fleecePhase fleece
Degree of separation99,99 %99,9999 %99,9999 %99,99999 %
Filter fineness3 µ1 µ0,01 µ0,01 µ
Residual oil content–0,5 mg/m³ (Liquid oil)0,01 mg/m³ (Liquid oil)0,001 mg/m³ (Liquid oil)
Operating overpressure16, 50, 35016, 50, 35016, 50, 35016, 50, 350
Nominal volume flow [m³/h]30 – 30.00030 – 30.00030 – 30.00030 – 30.000
Purity class according to DIN ISO 8573-1 (particles: moisture: oil)3:-:-2:-:31:-:11:-:1
Applicationlarger quantities of solid or liquid, coarse contaminationMedium quantities of solid or liquid, fine contaminationSmall quantities of solid or liquid, very fine contaminationSmall quantities of solid or liquid, very fine contamination
Sterile filterActivated carbon filterActivated carbon adsorber
Filter materialPhase fleecePhase fleece vaporized with activated carbonActivated carbon fill
Separation efficiency99,99999 %––
Filter fineness0,01 µ––
Residual oil content–< 0,003 mg/m³ (Oil Steam)< 0,003 mg/m³ (Oil Steam)
Operating overpressure16, 50, 35016, 50, 35011, 16
nominal voume flow [m³/h]30 – 3.500 m³/h30 – 30.000 m³/h8 – 20.420 m³/h
Purity class according to DIN ISO 8573-1 (particles: moisture: oil)1:-:1-:-:0-1-:-:0
Applicationmicrobiological organisms with the option of sterilizationGaseous contaminants, especially oil vaporGaseous contaminants, especially oil vapor

Processing Technology