Fisher™ 656 Direct-Acting Diaphragm Actuator
Fisher 656 diaphragm actuators provide small to medium thrust output for bracket-mounted applications. Such applications include operation of Butterfly valves and built-in turbine valves, louvers, dampers, and other similar equipment.
The Fisher™ 656 Direct-Acting Diaphragm Actuator is a rugged, spring-opposed pneumatic actuator designed for precise linear valve control in demanding industrial applications. Manufactured by Emerson, the 656 actuator provides dependable, accurate, and smooth operation of sliding-stem control valves used in oil and gas, petrochemical, refining, power generation, and process automation industries. As a direct-acting actuator, the Fisher 656 uses air pressure applied to the diaphragm to move the actuator stem downward, while the spring opposes this motion—allowing fail-up (fail-open) operation upon air supply failure. This makes it ideal for control systems requiring a fail-open safety function. The 656 actuator features a rolling diaphragm design, providing excellent sensitivity, stability, and repeatability over its entire stroke range. Its heavy-duty spring and pressure-balanced construction deliver high thrust output while minimizing friction and hysteresis for accurate valve positioning. Built with durable steel components and a corrosion-resistant finish, the Fisher 656 actuator is engineered for long service life and reliable performance under harsh operating conditions. It integrates seamlessly with Fisher control valves, DVC digital valve controllers, and positioners, ensuring optimal performance in both modulating and on/off control applications.
Technical Specification of Fisher™ 656 Direct-Acting Diaphragm Actuator
- Actuation
- Spring-return, Linear
- Certifications
- PED, CUTR, ATEX
- Control Type
- On/Off, 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™ 656 Direct-Acting Diaphragm Actuator
- Maximum thrusts of up to 5.3 kN (1,200 lbf) can be produced, depending on construction.
- Depending on size, strokes of up to 105 mm (4 1/8 in) are available.
- Four tapped holes in the actuator base permit either bracket or plate mounting.
- A wide spring selection is available for nearly any control application.
- Rugged yoke and casings provide stability and corrosion-resistant protection.
- Available with a top-mounted handwheel for manual override control.