This larger actuator is used on the larger valve sizes to provide the heavier operating forces desirable for driving these longer travel valves far enough for adequate flow capacity. A much larger area bellows is used to develop the thrust necessary per unit of temperature change. The frame is cast iron and a knurled wheel is used to adjust the spring force to balance the pressure differential across the valve and to balance the valve at the travel required by the flow necessary to maintain the system load (heat transfer).

This bellows requires a larger bulb due to the bellows volume. Refer to the bulb dimensions table for the type valve needed to determine the required bulb size. Wells for these bulbs have a 1 1/2" NPT male thread.

These units are recommended only when the preferable pneumatic control valves are not acceptable.

© Pneumatic Control, Inc. 1999/2000