The GDHM Series Air Dryers use the proven
“Pressure Swing Adsorption” (PSA) method for drying wet compressed air. This requires having two identical towers containing hygroscopic desiccant. Incoming wet air enters the dryer through a shuttle valve where it is directed to the bottom of the tower containing dry desiccant. The desiccant in this tower removes 99.7+% of the water vapor from the air when operated at catalog conditions. The dried air leaving the top of the tower is directed to the outlet through a second shuttle valve. In this outlet shuttle valve a built-in orifice allows a portion of the dried air to flow into the other tower being regenerated.
The orifice reduces the high pressure air down close to atmospheric pressure which lowers the dew point of the dried air even further. The tower being regenerated/purged of moisture is connected to an energized solenoid valve for a controlled period of time. The electrical signal to the solenoid is monitored by an LED light on the solid state timer. After the desiccant is regenerated, the timer shuts off the power to the solenoid valve. Air continues to flow through the orifice to repressurize the regenerated tower to line pressure. The middle light on the timer indicates the repressurization function.
Next, the timer opens the valve on the tower containing the wet desiccant. This shifts the shuttle valve balls, and the tower with the wet desiccant is regenerated while the other tower continues to dry the air. Examining the flow schematic to the right demonstrates the air dryer process operation.