Product Critical Technical Advantages
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Streamlined Mounting & Tubing: The 657 features an integral mounting pad, which removes the need for traditional brackets and reduces the parts required for assembly. When used with Fisher FIELDVUE™ instruments, an integral air passage eliminates external tubing, significantly reducing the risk of leaks and mechanical damage.
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High-Response Design: By utilizing a shallow casing on the pressure side, the internal volume is minimized. This design ensures faster response times to signal changes, making it ideal for precision throttling applications where process stability is critical.
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Linear Thrust Delivery: The actuator employs a molded diaphragm that travels within a deep casing. This architecture minimizes the change in effective diaphragm area throughout the stroke, ensuring consistent thrust and linear movement across the entire travel range.
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Industrial Durability: Constructed from thick-walled cast iron and steel, the 657 provides superior stability and corrosion protection. This heavy-duty build is specifically engineered to withstand the vibration and harsh atmospheric conditions of refineries and chemical plants.
Key Specifications
| Feature | Technical Specification |
| Actuation Type | Pneumatic Direct-Acting (Air-to-Close) |
| Sizes | 30, 34, 40, 45, 46, 50, 60, 70, 80, 100 |
| Materials | Cast Iron and Steel |
| Travel Range | Up to 102 mm (4 inches) depending on size |
| Operating Temp | -40°C to +82°C (Standard); higher with special diaphragms |
| Manual Override | Top-mounted or side-mounted handwheels available |
Field of Application
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Refining and Petrochemical: Used for throttling control in high-pressure steam and hydrocarbon lines.
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Power Generation: Automating feedwater and cooling water systems where failsafe reliability is paramount.
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Oil & Gas Production: Integrated into skid-mounted equipment for pressure regulation and fluid separation.
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Pulp & Paper: Managing chemical additive flows and steam drying processes.
