The Type 766 actuator with integral top-mounted positioner.
A pneumatically operated, spring opposed diaphragm actuator. Designed to fit the Research Control Valve body-bonnet assembly.
The unit is available in two sizes: one for the 1/4″ valve and another larger version for the 1/2″ through 1″ valves. When equipped with the model BLRA positioner it functions as an air-to-open actuator. Retracting the stem and opening the valve on an increasing instrument signal. The unit is designed to extend the stem, closing the valve, on a decreasing or loss of instrument signal.
A force-balance system utilises the full force of the supply air. This positions the stem precisely and with a high degree of repeatability.
This type actuator is useful when the application calls for high positioning accuracy. When greater force is required over the standard actuator such as in the case of high shutoff pressures or excess packing friction.