Fisher 667NS Diaphragm Actuator｜The Gold Standard in Nuclear-Grade Reverse-Acting Actuators｜Fisher supplier

Product Critical Technical Advantages

• Seismic Resilience by Design: Unlike standard industrial actuators, the 667NS is built with thick-walled cast iron and steel. This heavy-duty construction provides the necessary rigidity to maintain valve control during and after seismic events, ensuring critical systems remain operational when they are needed most.

• Leak-Proof, Tubeless Integration: By incorporating an integral air passage, the 667NS allows for a seamless connection with Fisher FIELDVUE™ digital valve controllers. This eliminates external tubing—a frequent source of leaks and a vulnerability in high-vibration nuclear environments—streamlining both installation and long-term maintenance.

• High-Performance Response Times: Efficiency in nuclear thermal-hydraulic loops depends on speed. The 657NS utilizes a shallow pressure-side casing to minimize air volume, enabling the actuator to react almost instantaneously to control signals for superior throttling accuracy.

• Maximum Thrust, Minimum Area Change: The use of a molded diaphragm in a deep casing ensures that the effective area stays consistent throughout the stroke. This provides a linear and powerful thrust profile, allowing the 667NS to overcome high process pressures while maintaining precise positioning.

Engineered for Nuclear Safety: Key Specifications

Critical Nuclear Service Applications

• Emergency Cooling Loops: Dependable modulation for reactor and auxiliary cooling water.

• Primary Containment Isolation: Rapid-response on/off service for safety-critical barriers.

• Steam Control Systems: High-stability actuation for secondary-side steam distribution.

• Chemical & Volume Control: Accurate dosing for maintaining reactor coolant chemistry.