Butterfly valve (also known as flap valve) is a kind of regulating valve with round disc or disc as its closing part, which is mainly composed of valve body, valve rod, butterfly plate and sealing ring. The valve body is cylindrical with short axial length and built-in butterfly plate. The butterfly plate of theis installed in the diameter direction of the pipeline. In the cylindrical channel of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, with the rotation angle between 0 ° and 90 °. When it rotates to 90 °, the valve will be fully open.
Butterfly valve is simple in structure, small in volume and light in weight, and only consists of a few parts. Moreover, the valve can be opened and closed quickly with only 90 ° rotation, and the operation is simple. At the same time, the valve has good fluid control characteristics. When the butterfly valve is in the fully open position, the butterfly plate thickness is the only resistance when the medium flows through the valve body, so the pressure drop generated by the valve is very small, so it has better flow control characteristics. Butterfly valve has two types of seal: elastic seal and metal seal. Elastic sealing valve, sealing ring can be inlaid on the valve body or attached to the periphery of butterfly plate.
The life of butterfly valve with metal seal is generally longer than that with elastic seal, but it is difficult to achieve complete seal. The metal seal butterfly valve can adapt to higher working temperature, while the elastic seal butterfly valve has the limitation of temperature.
If butterfly valve is required to be used as flow control, the main thing is to correctly select the size and type of valve. The structure and principle of butterfly valve is especially suitable for making large diameter valve. Butterfly valve is not only widely used in petroleum, gas, chemical industry, water treatment and other general industries, but also in the cooling water system of thermal power station.
There are two kinds of butterfly valves commonly used: wafer butterfly valve and flange butterfly valve. The double clip butterfly valve is connected between two pipe flanges with stud bolts. The flange butterfly valve has flange on the valve, and the flange on both ends of the valve is connected to the pipe flange with bolts.