The valve is a control component in the pipeline fluid conveying system. It is used to change the cross-section of the passage and the direction of the medium flow. It has the functions of diversion, cut-off, adjustment, throttling, check, shunting, or pressure relief.

       Valves for fluid control, ranging from simple globe valves to various valves used in extremely complex automatic control systems. There are many varieties and specifications. The nominal diameter of the valve ranges from extremely small instrument valves to industrial ones with a diameter of up to 10m. Valves for pipelines. The valve can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals and radioactive fluids. The valve's working pressure can be ultra high pressure from 1.3х10MPa to 1000MPa, working temperature From ultra-low temperature of -269 ℃ to high temperature of 1430 ℃. The valve can be controlled by various transmission methods, such as manual, electric, hydraulic, pneumatic, worm gear, electromagnetic, electromagnetic-hydraulic, electric-hydraulic, pneumatic-hydraulic, spur gear, bevel gear drive, etc. ; It can act according to the predetermined requirements under the action of pressure, temperature or other forms of sensor signals, or simply open or close without relying on the sensor signals. The valve relies on driving or automatic mechanisms to make the opening and closing parts rise and fall. Move, rotate or swing, so as to change the size of the flow channel area to achieve its control function.

       A valve is a kind of pipeline accessory. It is a device used to change the cross section of the passage and the direction of medium flow and control the movement of the conveying medium. It has diversion, cutoff, adjustment, throttling, check, shunting, or pressure relief. Features. Specifically, the valve has the following uses:

       Shut-off valves: Connect or cut off the medium in each section of the pipeline. Such as gate valve, globe valve, ball valve, plug valve, diaphragm valve, butterfly valve, etc.

       Regulating valves: regulating the flow and pressure of the medium in the pipeline. Such as throttle valve, regulating valve, pressure reducing valve, safety valve, etc.

       Shunt valves: change the flow direction of the medium in the pipeline, used to distribute, separate or mix the medium. Such as distribution valves, three-way plug valves, three- or four-way ball valves, traps, etc.

       There are many types of valves. With the continuous improvement of the technological process and performance of various types of equipment, the types of valves are still increasing, but in general can be divided into two categories:

       Automatic valve

       A valve that relies on the ability of the medium (liquid, gas, steam, etc.) to act on its own. Such as safety valves, check valves, pressure reducing valves, traps, hydraulic control valves, emergency shut-off valves, exhaust valves, etc.

       Actuated valve

       Valves operated by manual, electric, hydraulic and pneumatic. Such as gate valve, globe valve, throttle valve, butterfly valve, ball valve, balance valve, plunger valve, plug valve and so on.

       The valve relies on an automatic or driving mechanism to make the opening and closing member move up, down, swing, or swing, thereby changing the size of its flow channel area to achieve its control function.

       In addition, the valve has the following classification methods.

       Divided by structural characteristics

According to the moving direction of the closed-opening member relative to the valve seat, it can be divided into:

       Gate-shaped: The closed-opening piece moves along the center line of the valve seat.

       Gate shape: The closed-opening piece moves in a direction perpendicular to the center line of the valve seat.

       Plugs and spheres: The headstock is a plunger or sphere that rotates around its own axis.

       Swing shape: The opening and closing piece rotates around the axis outside the valve seat.

       Butterfly: Disc of opening and closing parts, rotating around the axis inside the valve (center line type) or the axis outside the valve seat (eccentric type)

       Spool type: The opening and closing member slides upward in a direction perpendicular to the passage.

       Divided by manipulation method: According to different manipulation methods, it can be divided into:

       Manual valves-with the aid of a handwheel, handle, wrench, lever or sprocket, etc. Manually operated valves can be equipped with reduction gears such as worm gears and gears when large torque needs to be transmitted.

       Electric Valves-Valves operated by means of electric motors, solenoids or other electrical.

       Hydraulic or Pneumatic Valves-Valves operated by means of liquid (liquid media such as water, oil) or gas.

       Automatic valve-A valve that relies on the ability of the medium (liquid, gas, vapor) to act on its own.