what is a valve

A valve is a mechanical device 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 essential components of a piping system that conveys liquids, gases, vapors, slurries, etc. . They can be used to start or stop flow based on the valve state, regulate pressure or flow downstream, and operate on sophisticated automation systems. Valves can be classified into different types based on their characteristics and applications, such as check valves, ball valves, gate valves, globe valves, butterfly valves, and needle valves. Most valves have an inlet, an orifice or seat, a disk (or plug, seal, etc.) that seals against the orifice, and an outlet. Valves can be made of different materials, such as metal, plastic, or exotic alloys, depending on the process liquid and the valves function.