Rotary-Shaft Valves (Fisher V500)

Although they are less popular than sliding-stem control valves, a wide range of rotary-shaft control valves, including ball valves, butterfly valves, and rotary-plug valves, are also available. The components of a typical rotary-shaft control valve include the valve body and the trim as shown in Figure 4.

Valve Body – The valve body is the major fluid boundary and pressure-containing component. The valve body also supports and locates internal parts such as shafts, bushings, and seals. As Figure 4 indicates, many rotary-shaft valve designs do not include a separate bonnet.

Trim refers to all internal, process-wetted parts. Trim includes:
• A closure member in the form of a disk, ball, ball segment, or valve plug.
• A seal or seat ring that mates with the closure member to provide shutoff when the valve is in the closed position.
• A retainer that locates and secures the seal or seat ring in the valve body.
• A valve shaft that transmits torque to the closure member.
• Bearings and/or bushings that locate and support the valve shaft.
• Packing that prevents process fluid leakage along the valve shaft.

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