Suction side versus high pressure discharge drying technology

Higher concentration of water vapor per volume of gas, caused by high compressor discharge temperatures, affects the adsorption efficiency of desiccant dryers which are installed on the pressure discharge side. Oil vapor found at the outlet of the oil-lubricated compressor can contaminate the desiccant and cause dew point collapse. Lower temperatures and oil vapor free gas on the suction side result in better dryer performance and lower maintenance cost.

Allowing "wet" gas to enter the compressor is undesirable, as most reciprocating compressors are extremely sensitive to liquid water entering the compression cylinders, which can have catastrophic results on the entire compressor.

Pressure swing dryers use 10 - 15% of the dry gas from their outlet to regenerate the off-line tower. This used gas must then be recovered on the suction side of the compressor, increasing its size and decreasing the output to the storage vessels and dispensers. This is not an economical solution as compared to the suction side dryer which does not utilize any purge gas.