A refrigerated air dryer cools compressed air to condense water, reaching a pressure dew point of about 3°C. Sizing it correctly depends on the actual flow, inlet temperature, pressure and ambient conditions, not only the compressor nameplate.
Sizing factors
- Compressor free air delivery at the working pressure
- Air inlet temperature to the dryer
- Ambient temperature of the dryer location
- Required pressure dew point
Higher inlet and ambient temperatures reduce dryer capacity, so the dryer must be de-rated for hot conditions. The manufacturer correction factors convert nominal capacity to the capacity at your operating point.
Practical guidance
Choose a dryer rated at least equal to the compressor output after applying correction factors, and consider the pressure drop through the dryer when setting system pressure. Oversizing slightly is safer than running a dryer beyond its rated point, which raises the dew point and lets moisture through.