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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.
Fisher™ 685 Series Piston Actuators


Double-acting, Spring-return, Linear
PED, CUTR, ATEX, SIL capable
Control Type
Throttling, Positioning
Operating Temperature
Standard Temperature
Power Source
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.


  • 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.