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Simplifying Complexity. Delivering Safety.
Simplifying Complexity.
Delivering Safety.

In-line Filter Units

Pre-filtration system for Expo motor purge and pressurization systems


  • Reduces contaminants in incoming purge air
  • Increases purge system up-time and service life
  • Filtration capacities up to 14,000 Nl/min
  • Parallel filters for continuous running
  • Stainless steel enclosure construction

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  • Description
  • Specifications
  • Downloads
  • Manuals


To ensure long, trouble-free service, Expo’s purge and pressurization systems require good quality instrument quality compressed air. Our specifications are as follows (In line with: BS ISO 8573-1: 2010):

Particles per m³:     0.5 micron: < 20,00;  0.5 – 1.0 micron: <400;  1.0 – 5.0 micron: < 10

Oil per m³:              <0.1mg

Humidity:                Dew point at least 10°C below ambient. Never greater than 3°C

In cases where the air supply cannot be guaranteed to continuously meet this specification, Expo recommends the use of an additional in-line filter unit to pre-clean the purge air.

The system comprises a stainless-steel enclosure with two parallel filter lines. Each filter line can be isolated and blown down for maintenance or change-out, while maintaining flow through the other line to ensure 100% purge system and motor uptime.


Air Inlet
System for Size 5 Motor Purge - 5 - 6 bar (73 to 232 psi)
System for Size 7 Motor Purge - 5.2 - 8 bar (75 to 116 psi)
Temperature range
-10°C to +55°C
System variants
ASU-0000-008 Size 5 system up to 6,000 Nl/min (212 SCFM)
ASU-0000-009 Size 7 system up to 14,000 Nl/min (494 SCFM)