The GDHM Series desiccant air dryers use the proven “Pressure Swing Adsorption” (PSA) method for drying wet compressed air. This requires having two identical towers containing hygroscopic desiccant. The unique design of the GDHM Series allows for the dryer to start and stop with a compressor or point-of-use equipment to eliminate purge loss when off. The solid state memory feature allows the dryer to start where it left off in the drying cycle to prevent wet air downstream.