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Modular Compressed Air Purification
Ultrafilter FRL

Authorized Distributor of:

Modular Compressed Air Purification

FRL modular dryers utilize VarioDry membrane modules and include integrated prefiltration and pressure regulation. Where required, an integrated activated carbon filter can be added for hydrocarbon vapor removal.

Bundled Advantages

The use of a membrane compressed air dryer integrated in the Ultrafilter FRL-unit combines several unique advantages in a single device:

  • almost silent operation allows direct workshop installation
  • no power supply required
  • inherently safe device, applicable in hazardous areas
  • no oxygen depletion, suitable for
    breathing air application

Membrane Dryer VarioDry FRL

Cross section of the hollow membrane
fibers. Taken with extreme magnification by
means of a scanning electron microscope.
The membrane wall thickness is approx.
150 micrometer.

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Technical Data

Superior Concept:
Integrated Membrane Dryer

The integration of a dryer in the FRL-unit itself offers some major advantages like

  • Tuned to form a complete package
  • No additional fittings required
  • Identical housing design guarantees lowest differential pressure
  • No danger of leakage since external adapters or interconnecting devices are not used

Air coming from the prefilters enters the integrated dryer and is fed through the center of a bundle of hollow fibers with semi permeable membranes. Moisture diffuses across the semi permeable membrane as air moves through the centre of the hollow fiber bundle. The dry air produced leaves the system in order to drive the application or to enter the next purification step respectively with a portion of it fed back over the outside of the fiber bundle and vented to atmosphere via outlets.

A throttle nozzle controls the continuous volume of sweep or purge air. No condensate is generated during the drying process since dehumidification takes place in the gas phase completely.

Performance of the integrated membrane dryer for a given application will be a function of inlet conditions to the system. Varying inlet conditions will produce varying outlet conditions, although a discrete Pressure Dew Point (PDP) reduction within the dryer takes place.


Leaving the last filtration stage the compressed air is free of dirt particles oil and water but far away from being dry. A temperature drop of only 34 °F will result in water vapor condensing again – a fact which cannot be prevented by any filtration technology.

The reason behind is the natural process that air at a relative humidity of 100% condenses and water is set free with falling temperatures of the air.

A fact that illustrates best the necessity of a FRL integrated dryer because only drying the air reliably prevents condensate from forming downstream of the filters. All FRLunits benefit from Ultrafilter’s long-standing experience in manufacturing air dryers.

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JPL Air Compressor Service specializes in industrial air compressor in California and across United States.