According to Walmec North America, the WNA AMD-035 Membrane dryer has a 4-stage pre-filtration that is critical to the longevity and function of the membrane dryer.
The first and second stage filters remove moisture, liquids, dust, rust, scale, and other contaminants to 5 microns. An automatic float drain under the second stage filter opens and expels all collected liquids whenever an ounce or more is present. It is fully automatic with no continuous air loss. The third and fourth stages remove any remaining particles down to .01 microns as well as absorbing any remaining moisture or oil vapors. The Membrane Dryer lowers the humidity level by venting it harmlessly into the surrounding atmosphere. A flexible input hose assembly eliminates the hazards of damage from vibrations in piped compressed air systems and allows the Membrane Dryer itself, to be installed in any position.