Where the water comes from
Air contains water vapour in proportion to its temperature and humidity. Compressing it raises the pressure and the temperature; cooling it afterwards forces the vapour to condense. A receiver, a dryer and every low point in the pipework are places where that liquid collects. None of it disappears on its own.
The three collection points
- Aftercooler and receiver - the bulk of the condensate forms here, as the hot discharge air cools.
- Dryer - a refrigerated dryer condenses further and drains continuously; an adsorption dryer regenerates and releases moisture on a cycle.
- Filters and line low points - coalescing filters collect oil and water; drip legs collect what the pipework sheds.
Drains: the failure that looks like a dryer fault
A failed drain shows up as water at the tool, and the usual first reaction is to blame the dryer. Timer drains are the common cause: set too long and they waste compressed air, set too short and the bowl floods. Zero-loss drains avoid the air loss but have their own failure modes. Whatever type is fitted, drains need to be checked as part of routine maintenance, not discovered when a process fails.
Oil in the condensate
In an oil-injected compressor, the condensate contains oil. Discharging it to a surface drain is both a compliance problem and a wasted resource. An oil-water separator takes the condensate, separates the oil for collection and discharges water within the permitted limits. The separator element is a consumable and has to be replaced on schedule; a saturated element passes oil straight through.
Practical layout
| Point | Good practice |
|---|---|
| Receiver drain | Automatic, with a manual check point |
| Dryer drain | Continuous or frequent cycling, routed separately |
| Filter drains | Individual, so a failure is traceable |
| Low points | Drip legs with a drain, not a blind cap |
| Disposal | Oil-water separator before any drain connection |
Send us your working pressure, required flow and site conditions and we will propose a configuration. Contact OPPAIR.