Valves are control components in fluid systems and possess functions such as cutoff, regulation, diversion, prevention of backflow, pressure stabilization, flow division, or overflow pressure relief. For valves used in fluid control systems, the varieties and specifications range from the simplest stop valves to various valves used in extremely complex automatic control systems, which are quite numerous. Valves can be used to control the flow of various types of fluids, including air, water, steam, various corrosive media, mud, oil products, liquid metals, and radioactive media.
A valve is a device in a fluid system that controls the direction, pressure, and flow rate of the fluid. It is a device that enables the medium (liquid, gas, powder) in piping and equipment to flow or stop and can control its flow rate. A valve is a control component in a pipeline fluid system. It is used to change the cross – sectional area of the passage and the flow direction of the medium and has functions such as diversion, cutoff, throttling, check, flow division, or overflow pressure relief. For valves used in fluid control, from the simplest stop valves to various valves used in extremely complex automatic control systems, there is a wide variety of varieties and specifications. The nominal diameter of valves ranges from extremely small instrument valves to industrial pipeline valves with a diameter of up to 10m. Valves can be used to control the flow of various types of fluids, such as water, steam, oil products, gases, mud, various corrosive media, liquid metals, and radioactive fluids. The working pressure of valves can range from 0.0013MPa to 1000MPa ultra – high pressure, and the working temperature ranges from – 269℃ ultra – low temperature to 1430℃ high temperature. The control of valves can adopt a variety of drive methods, such as manual, electric, hydraulic, pneumatic, turbine, electro – magnetic, electro – hydraulic, electro – hydraulic, pneumatic – hydraulic, spur gear, and bevel gear drive. They can operate as required under the action of pressure, temperature, or other forms of sensing signals, or simply open or close without relying on sensing signals. Valves rely on drive or automatic mechanisms to make the opening and closing parts perform lifting, sliding, swinging, or rotating movements, thereby changing the size of their flow channel area to achieve their control functions.
