Research Control® Valves Actuator, Pneumatic (Type 755)

The Type 755 actuator is a pneumatically operated, spring-opposed diaphragm actuator designed specifically to fit the Research Control Valve body-bonnet assembly. The unit is available in two sizes: one to fit the 1/4" valve and a larger version to fit the 1/2" through 1" valves. It provides smooth linear extension of the valve stem upon an increasing instrument signal. A decrease in instrument signal causes the stem to retract and open the valve. Downward closing force is generated by instrument air on top of the diaphragm. An increasing pressure in the diaphragm cavity opposes the force of the spring and extends the stem, closing the valve. The unit is designed to retract the stem, opening the valve, should the instrument signal fail.