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Fisher™ 785C Piston Actuator
Fisher 785C
The 785C is a piston actuator that provides accurate, high thrust output for a wide range of travel applications.
This actuator can be single- or double-acting and spring-return or springless with a selection of spring-fail options available. The 785C family is designed for use with a variety of Fisher sliding-stem control valves. It is available in several configurations to cover a wide range of application requirements.
Fisher™ 785C Piston Actuator


Single-Acting or Double-Acting, Spring-Return or Springless
PED, ATEX, CUTR, SIL 3 Capable
Control Type
On/Off, Throttling, Positioning
Operating Temperature
Standard Temperature
Power Source
Process Control
On/Off, Throttling, Positioning
Valve Type
Angle Valve, Globe Valve
Max Operating Pressure (PSI)
12 bar (174 psig)


  • High Thrust Capability — Thrusts of up to 1600 kN (359,000 lbf) for double acting springless and 540 kN (121,000 lbf) for spring-return can be produced.
  • Broad Application Coverage — Standard constructions offer travels of up to 203 mm (8 inches) and cylinder diameters of up to 685 mm (27 inches). Special constructions offer travels up to 610 mm (24 inches). For travels greater than 610 mm (24 inches) consult your Emerson sales office.
  • Double-Acting Springless Construction — Pressure on both sides of the piston results in stiff, precise positioning.
  • Single-Acting Spring Return — Allows for full ANSI/FCI 70-2 CL V shutoff upon loss of air without use of a volume tank.
  • Low Friction — Low friction piston seals and electroless nickel plated cylinders reduce sliding friction and wear.
  • Wide Temperature Range — Standard constructions offer a temperature range of -20 to 100C (-4 to 212F), however lower temperatures are possible. Low temperature constructions offer ranges of -40 to 100C (-40 to 212F) or -60 to 100C (-76 to 212F). High temperature constructions offer ranges of -20°C to 200°C (-4°F to 392°F).
  • Mechanical Fail Mode — Depending on construction, an internal bias spring will force the piston rod to retract or extend upon a loss of supply pressure.
  • Manual Override — An optional top-mounted handwheel or side-mounted handpump is capable of extending or retracting the actuator manually.