The Fisher 667-34 actuator is a spring-opposed diaphragm actuator designed for reliable pneumatic control of valves, particularly in throttling and on/off applications. It belongs to the 667 series, which is known for reverse-acting operation and robust construction.

Key Specifications of Fisher 667-34

• Actuator Type: Pneumatic diaphragm, spring-opposed
• Size: 34 (mid-range size in the 667 series)
• Action: Reverse-acting — air pressure pushes the diaphragm downward to open the valve
• Travel Range: Typically 19 mm (0.75 in) for size 34
• Maximum Supply Pressure: Up to 2.4 bar (35 psig), depending on spring configuration
• Bench Set: Adjustable spring compression to define travel span and fail-safe position
• Mounting: Top-mounted on compatible Fisher control valves
• Manual Override: Optional handwheel assemblies available for manual positioning
• Construction Materials: Steel diaphragm casing, corrosion-resistant components