Critical Technical Advantages
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Seismic-Ready Structural Integrity: The 667NS2 is built with thick-walled cast iron and steel, offering a high-mass, rigid construction. This design is specifically engineered to maintain precise valve modulation during seismic events, providing the stability and corrosion protection essential for long-term nuclear service.
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Tubeless Fluid Power Integration: Innovation meets safety with the 667NS2’s integral air passage. When paired with Fisher FIELDVUE™ instruments, the need for external tubing and fittings is eliminated. This tubeless setup removes potential leak paths and protects the air signal from mechanical vibration and accidental damage.
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Rapid-Response Casing Design: In critical control loops, every millisecond counts. The 667NS2 features a shallow pressure-side casing that reduces internal air volume. This specialized geometry minimizes response time, allowing the actuator to react instantly to controller signals for superior process stability.
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Linear Thrust through Molded Diaphragms: A deep diaphragm casing houses a precision-molded diaphragm, ensuring the effective area change is kept to a minimum throughout the entire travel. This results in maximum thrust delivery and highly predictable, linear stem positioning across the valve’s full stroke.
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Streamlined Installation and Maintenance: The integral mounting pad eliminates traditional, multi-part mounting brackets. This reduces the number of components that require inspection and ensures perfect alignment between the actuator and the positioner, simplifying both initial setup and periodic maintenance.
Technical Performance Matrix
| Feature | Engineering Specification |
| Action Type | Reverse-Acting (Air-to-Push Up) |
| Qualification | Nuclear Service Tier 2 (NS2) |
| Mounting System | Integral Pad (reduces part count) |
| Pneumatic Interface | Internal Air Passage (Tubeless) compatible |
| Housing Materials | Heavy-duty Cast Iron and Carbon Steel |
| Customization | Supports manual operators and adjustable travel stops |
Primary Applications in the Nuclear Sector
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Auxiliary Feedwater Control: Ensuring consistent water supply to steam generators.
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Component Cooling Systems: Precise temperature management for safety-critical equipment.
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Chemical Volume Control Loops: High-accuracy dosing for reactor coolant chemistry.
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Emergency Isolation Service: Dependable failsafe operation for containment barriers.
