Critical Technical Advantages
-
Massive Thrust Capability: The 685 series is built for heavy-duty service, capable of producing maximum thrusts up to 354 kN (79,000 lbf). This immense power allows for the reliable modulation of very large valves against high differential pressures, ensuring tight shutoff and precise control.
-
Extended Stroke Ranges: To accommodate the long travel requirements of large globe and angle valves, the 685 series offers strokes up to 610 mm (24 inches). This makes it one of the most versatile choices for high-capacity flow control applications.
-
Stiff and Stable Positioning: The double-acting construction utilizes air pressure on both sides of the piston to create a mechanically “stiff” assembly. This rigidity is essential for preventing valve plug instability and vibration when handling turbulent or high-velocity process fluids.
-
Reliable Failsafe Options: For safety-critical loops, internal bias spring constructions are available. These springs provide a dependable mechanical fail-open or fail-close mode upon loss of supply air, protecting the plant and personnel during emergency shutdowns.
-
Advanced Friction Reduction: To ensure smooth, repeatable movement and reduce “stiction,” the 685 series incorporates low-friction piston seals and specialized cylinder coatings. These enhancements minimize mechanical wear and allow the actuator to respond to minute signal changes from the controller.
-
Dual Manual Override Solutions: For manual operation, all sizes can be equipped with a rugged side-mounted handwheel. For the massive size 28 actuator, a specialized hydraulic hand pump is utilized to provide the necessary mechanical advantage for manual override control.
Technical Performance Matrix
| Feature | Details |
| Actuator Type | Double-Acting or Spring-Return Piston |
| Maximum Thrust | Up to 354 kN (79,000 lbf) |
| Maximum Stroke | Up to 610 mm (24 inches) |
| Compatibility | easy-e™, HP, EH, FB, and 461 Valves |
| Failsafe Mode | Spring-to-Extend or Spring-to-Retract |
| Manual Override | Side-mounted Handwheel or Hydraulic Pump |
Primary Applications
-
Main Steam Isolation: High-thrust automation for large-bore steam valves in power generation.
-
Severe Service Throttling: Managing high-pressure drops in chemical and hydrocarbon processing.
-
Feedwater Control: Precise modulation of high-capacity water cycles in utility plants.
-
Emergency Shutdown (ESD): Utilizing spring-return variants for high-force failsafe isolation in large pipelines.
