Two families, two dew points
A refrigerated dryer cools the air and condenses moisture, reaching a pressure dew point a little above freezing. An adsorption (desiccant) dryer passes air through a regenerating bed and reaches much lower dew points, at the cost of purge air and energy. Our refrigerated range covers 1.5 to 25 m3/min with a dew point band of 2 to 10 C; the twin-tower adsorption range covers 1.2 to 55 m3/min for duties that need a drier line.
| Requirement | Refrigerated | Adsorption |
|---|---|---|
| General workshop air | Suitable | Over-specified |
| Outdoor or unheated pipework | Risky in winter | Appropriate |
| Laser cutting and optics | Marginal | Usual choice |
| Pharmaceutical and food contact | Depends on the standard | Common |
| Energy and purge air | Low | Higher - purge consumes dried air |
Why nominal flow is not enough
Dryer capacity is quoted at a reference inlet temperature and pressure, often around 35 to 45 C inlet air and 7 bar. A compressor running at 10 bar delivers hotter air, and a dryer asked to handle that inlet temperature at full flow will not reach its rated dew point. Sizing has to use the actual inlet temperature, the actual pressure and the actual flow - which is why the dryer, not the compressor, is often the component that is quietly undersized.
Placement
- After the aftercooler - always; a dryer fed with hot air is being asked to do the aftercooler's job.
- After the receiver - allows bulk condensate to drop out before the dryer sees it, in most layouts.
- Before the filters - so the filters are not loaded with water.
- With a working drain - a dryer without a functioning drain is a very expensive pipe.
Matching to the compressor
The dryer should be sized for the compressor's flow at the working pressure with margin, and its pressure rating must exceed the system pressure. A 16 bar system needs a dryer and filters rated for 16 bar, not a 10 bar unit with a higher relief setting.
Browse the range on the air dryer collection page.
Tell us the working pressure, flow and site conditions and we will propose a configuration. Contact OPPAIR.