The quality of filtration and dryness required of the air supply differs for each application. But generally, compressed air can be classified in terms of dryness and cleanliness: Shop Air, Plant Air, and Instrument Air. (Not standard industry terms).

Compressed air is dried in three ways — in refrigeration, regenerative desiccant, or deliquescent dryers. This application example pdf illustrates simply these processes.

The monitoring process begins at the plant distribution line, see graphic on the Application pdf, and typical installations of continuous monitoring consist of an AMT or PDT dew point transmitter and a single-channel Model DS1200 or DS4000 dewpoint analyzer. If multiple dryers require moisture/dewpoint to be monitored, then a transmitter and sensor holder/sample cell should be installed to each dryer. 

Alpha Moisture Systems are manufactures and global distributors of dew point instrumentation, and also provide a design service for sampling systems etc. – see website or contact us for more details.