Valve is a device used to control the flow of fluids, pressure and flow direction, which is very widely used, and it has a close relationship with people’s daily life, such as faucets for tap water pipes and pressure reducing valves for liquefied petroleum gas stoves. Valves are also an indispensable part of various mechanical equipment such as internal combustion engines, steam engines, compressors, pumps, pneumatic transmissions, hydraulic transmissions, vehicles, ships and aircraft. The fluids that are controlled are diverse and can be liquids, gases, gas-liquid mixtures, or solid-liquid mixtures.
Valves are usually composed of valve body, bonnet, seat, opening and closing parts, actuation mechanism, seals and fasteners, etc. The control function of the valve is realized by the driving mechanism or the fluid driving the lifting, sliding, swinging or slewing movement of the hoist to change the size of the flow channel area.
