What is a valve closure member?

A valve closure member is a mechanical component used in valves to control the flow of fluids. It is typically a movable part that opens or closes a passageway within a valve to regulate or shut off the flow. The closure member is usually actuated by an external force, such as a manual lever, a spring, or an actuator, and can be made of various materials depending on the valve's specific application and the fluid being handled. Some common types of valve closure members include:

1. Disc: A flat or round-shaped closure element that moves perpendicularly to the flow path. It can be used in various valve designs such as ball valves, butterfly valves, and diaphragm valves.

2. Ball: A spherical closure element that seals the flow passage by rotating within the valve body. Ball valves are known for their quick quarter-turn operation.

3. Gate: A wedge-shaped closure element that moves linearly across the flow path, blocking or opening it. Gate valves are commonly used for full bore flow control.

4. Plug: A cylindrical or tapered closure element that is turned or inserted into the valve body to control the flow. Plug valves offer good sealing performance and are suitable for abrasive or viscous fluids.

5. Diaphragm: A flexible membrane or sheet that flexes or bends to control the flow. Diaphragm valves do not require a precise seal between moving parts, making them suitable for corrosive or high-purity applications.

6. Flapper: A hinged or pivoted closure element that opens and closes by swinging around a pivot point. Flapper valves are commonly used in check valves to prevent the backflow of fluids.

The selection of a specific valve closure member depends on factors such as valve type, pressure rating, temperature range, fluid compatibility, and desired flow control characteristics.