Butterfly butterfly valve installed in the pipe diameter direction. In the butterfly valve body cylindrical channel, the disc-shaped disc rotates about the axis, the rotation angle is between 0 ~ 90 ~, when rotated to 90 ~, the valve is fully open state. Butterfly valve structure is simple, small size, light weight, only a few components. And just turn the 90 & # 176; to quickly open and close, easy to operate, while the valve has good fluid control features. When the butterfly valve is fully open, the thickness of the disc is the only resistance to the flow of the medium through the valve body, so the pressure drop across the valve is small and therefore has good flow control characteristics. Butterfly valve seal and metal seal two types of seal. Flexible sealing valves, seals can be embedded in the body or attached to the butterfly plate around. Valves with metal seals generally have a longer life than elastomeric valves, but are harder to seal completely. Metal seals can adapt to higher operating temperatures, while flexible seals have temperature-limited defects. If the butterfly valve is required to be used as a flow control, the main choice is the correct size and type of valve. The structural principle of the butterfly valve is especially suitable for making large diameter valves. Butterfly valve not only in the oil, gas, chemical, water treatment and other general industry has been widely used, but also used in thermal power station cooling water system. Commonly used butterfly valve clamp butterfly valve and flange two. Butterfly Valve with the valve head bolt connection between two pipe flanges, flange type butterfly valve is a valve with a flange, both ends of the flange bolts with the valve connected to the pipe flange. Valve strength performance refers to the ability of the valve to withstand medium pressure. Valves are mechanical products subject to internal pressure and must therefore have sufficient strength and rigidity to ensure long term use without rupture or deformation.