A device used in a fluid system to control the direction, pressure, and flow of a fluid. A valve is a device that flows or stops and controls the flow of the medium (liquids, gases, powders) in the piping and equipment. Valves can be used to control the flow of fluids such as air, water, steam, various corrosive mediums, mud, oil, liquid metals and radioactive media.
Valves are the control parts of the piping fluid conveying system, which is used to change the direction of the passage cross-section and the medium flow, with the function of diversion, cut-off, throttle, check, shunt or overflow pressure. Valves for fluid control, ranging from the simplest cut-off valves to a variety of valves used in an extremely complex automatic control system, its variety and specifications are manifold, the nominal diameter of the valve is large from the tiny meter valve to the diameter reaches 10m of industrial piping valves.