Category: Control Valve

Liquid Service – Sizing Information

The following section is based on ISA-S75.01, “Flow Equations for Sizing Control Valves.” The reader is referred to that standard for more complete discussion of these equations and methods. As that standard points out, these equations are not intended for situations involving mixed-phase fluids, dense slurries, dry solids, or non-Newtonion liquids. In these cases the […]

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Control-Valve Actuators

Pneumatically operated control-valve actuators are the most popular type in use, but electric, hydraulic, and manual actuators are also widely used. The spring-and-diaphragm pneumatic actuator (see Fig. 4-28) is commonly specified, due to its dependability and its simplicity of design. Pneumatically operated piston actuators provide integral positioner capability and high stem-force output for demanding service […]

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Control-Valve Bodies

The control-valve body (see Fig. 4-27) regulates the rate of fluid flow as the position of the valve plug is changed by force from the actuator. Therefore, the valve body must permit actuator thrust transmission, resist chemical and physical effects of the process, and provide the appropriate end connections to mate with the adjacent piping. […]

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