Butterfly valve refers to the valve that the opening and closing parts (butterfly disc) are driven by the stem and rotate around the axis of the stem.
The butterfly valve consists of valve body, stem, disc and a sealing ring. The valve body is cylindrical, with a short structure length and a built-in disc-shaped.
The valve is driven by the valve stem and can rotate from 0 to 90 degrees. When it is 0 degrees, the butterfly plate is vertically closed with the axis of the valve body, and the butterfly plate is rotated 90 degrees.
When the axis of the butterfly plate is consistent with the axis of the valve body, it is all opened. By changing the deflection angle of the disc, the flow of the media can be controlled. Butterfly valve is a kind of regulating valve with simple structure, and it can also be used for switch control of low pressure pipeline. The butterfly valve pipeline is mainly used for cutting off and throttling. Its main advantages are short length and light weight. Compared with the gate valve, the butterfly valve has the advantages of short opening and closing time, small operating torque, small installation space and light weight, and the opening and closing of the butterfly valve is easy to be combined with various driving devices, and has good durability and reliability. The butterfly valve and the butterfly stem have no self-locking ability, so for the positioning of the butterfly plate, a worm gear reducer should be installed on the valve stem. The use of worm gear reducer can not only make the butterfly plate have self-locking ability, make the butterfly plate stop in any position, but also improve the operation performance of the valve. The industrial special butterfly valve is characterized by high temperature resistance, high pressure range, large nominal size of the valve, the valve body is made of carbon steel, and the sealing ring of the valve plate is made of metal ring instead of rubber ring. The large high temperature butterfly valve is made of steel plate welding, which is mainly used for flue duct and gas pipeline of high temperature medium. Generally speaking, the butterfly valve has the advantages of simple structure, small volume, light weight and easy adjustment; convenient opening and closing, labor-saving, low fluid resistance and convenient operation; it can transport mud and accumulate the least liquid at the mouth of the pipe; good sealing can be achieved under low pressure. The disadvantage of butterfly valve is: small range of operating pressure and working temperature, poor tightness. The butterfly valve is driven by manual, worm gear, electric actuator, pneumatic actuator and other ways, which can realize remote control and automatic operation. The driving mode of butterfly valve can be manual, electric or pneumatic, and turbine worm is often used in manual mode.
