Structural principle and application analysis of butterfly valve

Butterfly valve is a kind of regulating valve with round disc or disc as the closing part, which is mainly composed of valve body, valve stem, butterfly plate and sealing ring.The valve body is cylindrical, with short axial length and built-in butterfly plate.The butterfly plate of the butterfly valve is installed in the diameter direction of the pipe.In the cylindrical channel of the butterfly valve body, the disc shaped butterfly plate rotates around the axis with a rotation angle of 0°~90°. When the rotation angle reaches 90°, the valve is fully open.


The butterfly valve is simple in structure, small in volume and light in weight, and only consists of a few parts.Besides, the valve can be opened and closed quickly with only 90°rotation, which is easy to operate. At the same time, the valve has good fluid control characteristics.When the butterfly valve is in the fully open position, the thickness of the butterfly plate 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 good flow control characteristics.There are two sealing types of butterfly valve: elastic seal and metal seal.For elastic sealing valves, the sealing ring can be embedded on the valve body or attached to the periphery of the butterfly plate.
 
The service life of butterfly valve with metal seal is generally longer than that of butterfly valve with elastic seal, but it is difficult to achieve complete sealing.The metal seal butterfly valve can adapt to higher working temperature, while the elastic seal butterfly valve has the defect of being limited by temperature.
 
If the butterfly valve is required to be used for flow control, the main thing is to correctly select the size and type of the valve.The structure principle of butterfly valve is especially suitable for making large diameter valves.Butterfly valves are not only widely used in petroleum, gas, chemical, water treatment and other general industries, but also used in the cooling water system of thermal power plants.
 
There are two kinds of butterfly valves commonly used: wafer type butterfly valve and flange type butterfly valve.Wafer type butterfly valve uses stud bolts to connect the valve between two pipe flanges. Flange type butterfly valve has flanges on the valve, and bolts are used to connect the flanges on both ends of the valve to the pipe flanges.