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Globe valves are named for their spherical body shape with the two halves of the body being separated by an internal baffle. This has an opening that forms a seat onto which a movable plug[ 2] can be screwed in to close (or shut) the valve. The plug is also called a disc. [ 3]
Control valve. A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. [ 1] This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level. In automatic control terminology, a control ...
Control valves are normally fitted with actuators and positioners. Pneumatically-actuated globe valves and diaphragm valves are widely used for control purposes in many industries, although quarter-turn types such as (modified) ball and butterfly valves are also used. Control valves can also work with hydraulic actuators (also known as ...
Valve actuator. Electric actuator (blue cylinder) on a valve in a power plant. A black handwheel is visible on the actuator, which allows manual positioning of the valve. The blue valve body is visible in-line with the pipe. The valve actuator opens or closes the butterfly disc of the valve based on electrical signals sent to the actuator.
These water valves are operated by rotary handles. A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, but are usually discussed as a separate category.
Flow coefficient. The flow coefficient of a device is a relative measure of its efficiency at allowing fluid flow. It describes the relationship between the pressure drop across an orifice valve or other assembly and the corresponding flow rate . Mathematically the flow coefficient Cv (or flow-capacity rating of valve) can be expressed as. where.
Pinch valve, for slurry flow regulation and control. Piston valve, for regulating fluids that carry solids in suspension. Piston valve (steam engine) Plug valve, slim valve for on–off control but with some pressure drop. Solenoid valve, an electrically actuated valve for hydraulic or pneumatic fluid control.
The ASME B16 Standardization of Valves Flanges, Fittings and Gaskets Committee, which operates under ASME ’s Board on Pressure Technology Codes and Standards is responsible for standards covering valves, flanges, pipe fittings, gaskets and valve actuators for use in pressure services. The B16 Standards Committee currently meets once a year in ...