Fisher 657 and 667 actuators are designed to provide dependable on/off or throttling operation of control valves.These spring-opposed diaphragm actuators position the valve plug in the valve in response to varying controller or valve positioner pneumatic output signals. The 657 actuator is direct-acting, while the 667 is reverse-acting.
FeaturesThe integral mounting pad eliminates the traditional mounting bracket and reduces the number of parts required to mount.Incorporates an integral air passage that eliminates the need for external tubing and fittings when paired with a Fisher FIELDVUE™ instrument.Both 657 and 667 actuators are compatible with instruments that utilize traditional bracket-based mounting kits. The 667 can be externally tubed for instruments or accessories when required.Spring rates, travel stops, and manual operators are available for nearly any control valve application.A molded diaphragm travels in a deep diaphragm casing, minimizing area change throughout the travel.A shallow casing on the pressure side means reduced volume on that side, thereby minimizing response time.The molded diaphragm allows maximum thrust for given diaphragm size.Rugged thick-walled cast iron and steel construction provides increased stability and corrosion protection.
