Fisher™ 685 Series Piston Actuators
Fisher 685 series piston actuators provide medium to high thrust output for a variety of medium to very large Fisher sliding-stem valves, including the easy-e™, HP, EH, FB, and 461 valves. The double-acting design of the actuator results in stiff, precise positioning. Spring-return constructions are also available and offer a fail open or closed mode of operation when paired with a valve.
The Fisher™ 685 Series Piston Actuators, engineered by Emerson, are rugged and high-performance pneumatic actuators designed to provide precise linear motion for controlling sliding-stem valves in the most demanding process applications. Built for reliability, accuracy, and durability, the 685 Series delivers powerful thrust and rapid response for both on/off and modulating (throttling) valve operations. Using a piston-type pneumatic design, the 685 Series converts air pressure into linear motion with exceptional efficiency and control. These actuators are available in single-acting (spring-return) or double-acting configurations, offering flexible solutions for a wide range of industrial control systems. The compact, yokeless construction reduces side loading and friction, ensuring smooth valve operation and extended service life. Constructed from corrosion-resistant materials and designed for onshore, offshore, and corrosive environments, Fisher 685 Series actuators are ideal for oil and gas production, refining, chemical processing, and power generation industries. Their modular, field-serviceable design simplifies maintenance, while compatibility with Fisher control valves and accessories ensures seamless system integration and high operational reliability.
Technical Specification of Fisher™ 685 Series Piston Actuators
- Actuation
- Double-acting, Spring-return, Linear
- Certifications
- PED, CUTR, ATEX, SIL capable
- Control Type
- Throttling, Positioning
- Operating Temperature
- Standard Temperature
- Power Source
- Pneumatic
- Process Control
- On/Off, Throttling, Positioning
- Valve Type
- Angle Valve, Globe Valve
- Other Configurations
- Contact your local Emerson business partner or sales office to learn about additional specifications or options for this product.
Feature of Fisher™ 685 Series Piston Actuators
- Maximum thrusts of up to 354 kN (79,000 lbf) can be produced, depending on construction.
- Depending on size, strokes of up to 610 mm (24 in) are available.
- The double-acting construction allows for stiff, precise positioning.
- A side-mounted handwheel is available for all sizes except the size 28, which uses a hydraulic hand pump for manual override control.
- Internal bias spring constructions are available for applications requiring a mechanical fail mode.
- Low friction piston seals and cylinder coatings reduce sliding friction and wear.