Hankison Compressed Air Treatment: Filters, Dryers and Drain Selection
Image from Hankison.com
Q: My compressed air keeps wrecking air tools and clogging instrument air lines. Where does water and oil actually come from?
From compression itself. Squeezing air to 7–8 bar concentrates whatever moisture and oil aerosols were in the intake, and the aftercooler only removes part of it. Everything downstream — filters, dryers, drains — exists to strip the rest before it reaches your tools, valves and gauges. Hankison builds exactly these three layers.
Q: How do I know which filter grades I need, and in what order?
Order is always coarse to fine to carbon, in series. General purpose elements (<1 µm, <0.5 mg/m³) take out bulk particulate and water slugs; coalescing elements (0.01 µm) handle the aerosols that instruments and air bearings care about; activated carbon catches oil vapour where taste, smell or sensor contamination matters. Skipping straight to a fine element without a prefilter is the classic mistake — the element loads in weeks instead of a year.
Q: Refrigerated dryer or desiccant dryer — which one do I actually need?
Depends entirely on where the air ends up:
| Pressure dew point | Technology | Use it when |
|---|---|---|
| ~3 °C | Refrigerated | Indoor plant air, general pneumatics, no freezing lines |
| -40 °C or lower | Desiccant / membrane | Outdoor or unheated lines, instruments, freeze-risk circuits |
Size both to actual free-air delivery at working pressure — not nameplate compressor output — and leave margin for growth.
Q: Any installation details people get wrong?
Fit the treatment train after the receiver and before the points of use. Mount bowls vertically with access for checking. Route condensate drains into a sealed trap, never an open pipe — and prefer zero-loss electronic drains, which dump water without dumping the compressed air with it. Watch the pressure differential across each filter: a rising drop is the element telling you it is loaded. Elements typically go 12 months; dryer service follows the unit's running hours.