The function of the check valve is to allow the medium to flow in one direction only, and to stop the flow in the opposite direction. Usually this valve works automatically, the valve flap opens under the pressure of the fluid flowing in one direction; when the fluid flows in the opposite direction, the fluid pressure and the weight of the valve flap make the valve flap act on the valve seat, thus cutting off the flow.

Gate valve is an opening and closing member gate, the direction of movement of the gate is perpendicular to the direction of the fluid, gate valve can only be fully open and fully closed, not for regulation and throttling.When the valve is fully open, the entire flow channel is a straight passage, the pressure loss of the media operation is minimal. Gate valve is usually divided into several types according to the way of sealing parts, such as: wedge gate valve, plate gate valve, parallel duplex gate valve, wedge duplex gate valve. Different materials can be selected to convey water, steam, oil, natural gas, nitric acid, acetic acid, oxidizer and urea.

Ball valve was introduced in the 1950s, with the rapid development of science and technology, production process and product structure of the continuous improvement, the use of ball valves is rising year by year, ball valves are widely used in petroleum refining, long-distance pipelines, chemical, paper, pharmaceutical, water conservancy, electric power, municipal, steel and other industries. It has the action of rotating 90 degrees, and the plug body is a sphere with a circular through-hole or channel through its axis. Ball valve in the pipeline is mainly used to do cut off, distribution and change the flow direction of the medium, it only needs to use the operation of 90 degrees of rotation and a very small turning torque to close tightly. The ball valve is most suitable for on/off and cut-off valve. The ball valve has a compact structure and reliable sealing. Its sealing surface and ball surface are normally closed, which makes it resistant to the scouring of the medium and easy to operate and maintain.

The butterfly valve gets its name from the wing-like structure of the butterfly plate, which is installed in the diameter direction of the pipe. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis by only 90° to open and close the valve. The butterfly valve is simple in structure, small in size and light in weight. It consists of only a few parts. It can be opened and closed quickly by rotating only 90°, and it is easy to operate. The valve has good fluid control characteristics.