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Home / Products / Dryers / Membrane Dryers / FRL Modular Membrane Air Dryer

FRL Modular Membrane Air Dryer


The Donaldson FRL purification chain starts with a Filter-Water-Separator. It retains bulk particle contamination by a sieve effect and contains a cyclone separator to remove water and oil droplets from the compressed air.

The Filter-Water-Separator prevents the following high efficiency filter from bulk contaminants, and therefore avoids pollution related problems like short overall lifetime or high differential pressure.
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 semipermeable 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.