Butterfly valve, also known as flap valve, is a simple regulating valve that can be used for switching control of low-pressure pipeline media. Butterfly valve refers to a type of valve in which the closing element (disc or disc) is a disc that rotates around the valve axis to achieve opening and closing.

Butterfly valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil products, liquid metals, and radioactive media. It mainly serves as a cutting and throttling function on pipelines. The butterfly valve opening and closing component is a disc-shaped butterfly plate that rotates around its own axis inside the valve body to achieve the purpose of opening and closing or adjusting.

The butterfly plate of the butterfly valve is 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 a rotation angle between 0 ° and 90 °. When it rotates to 90 °, the valve is fully open. Butterfly valves have a simple structure, small size, and light weight, and are only composed of a few parts. And it can be quickly opened and closed by rotating 90 °, with simple operation, and 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 through the valve is very small, and it has good flow control characteristics.

Valves with metal seals generally have a longer lifespan than those with elastic seals, but it is difficult to achieve complete sealing. Metal seals can adapt to higher working temperatures, while elastic seals have the defect of being limited by temperature. If a butterfly valve is required for flow control, the main thing is to choose the correct size and type of valve. The structural principle of butterfly valves is particularly suitable for making large-diameter valves. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, and water treatment, but also in cooling water systems of thermal power plants.

There are two commonly used butterfly valves: wafer type butterfly valve and flange type butterfly valve. The wafer type butterfly valve is connected between two pipeline flanges using double headed bolts. A flange butterfly valve is a valve with a flange, which is connected to the pipeline flange by bolts at both ends of the valve.