Watson McDaniel Company Air Pilot-Operated Regulating Valve 1" HDA1

The HD or D Regulator with the “A” Air Pilot is used for reducing steam pressure on steam mains and process equipment. The “A” Air Pilot can also be used in conjunction with the PTR and PTL Pneumatic Controller for controlling temperature in process applications. The significant advantage of the “A” Air Pilot over standard spring-loaded pilots is that pressure adjustments to the regulator can be made from a remote location. A regulator placed in a difficult to reach or inaccessible location can now be adjusted by a control panel board placed in a convenient location. When air pressure is applied to the upper chamber of the air pilot it exerts a downward force on the air pilot’s diaphragm. The lower chamber of the air pilot is connected to the outlet side of the regulator using a sensing line. The purpose of the sensing line is to sense the pressure on the outlet side of the regulator. When the intended set pressure is reached the pilot valve closes which then closes off the flow path of steam to the underside of the diaphragm chamber in the regulator body. The regulator modulates maintaining the desired downstream pressure regardless of the amount of steam being used.