Valve  is the control component in the fluid conveying system, with the functions of cutting-off, regulation, diversion, upstream current prevention, pressure stabilization, diversion or overflow pressure relief. Valves used for fluid control systems, from the simplest stop valves to the extremely complex automatic control systems used in the various valves, their varieties and specifications are quite wide. Valves can be used to control the flow of various types of fluids, such as air, water, steam, various corrosive media, mud, oil products, liquid metals, and radioactive media