Butterfly valves have a simple structure. They are used for controlling the switch of the low-pressure pipeline medium. It mainly has two effects of cutting off and throttling in the pipeline. The ball valve with vertical mounting pad is used in the pipeline of conveying various corrosive and non-corrosive fluid medium in producer, natural gas, liquefied petroleum gas, chemical smelting, power environmental protection and other engineering system. Butterfly valves are usually classified as concentric 2PC ball valves, single eccentric butterfly valves, double eccentric butterfly valves and triple offset 1PC ball valves.
The concentric 2PC ball valve has a simple structure. Rubber lined butterfly valve belongs to this category. The single eccentric butterfly valve alleviates the excessive squeeze between butterfly plate and valve seat. The application range of single eccentric butterfly valve and concentric butterfly valve is nearly same; however, the single eccentric butterfly valve is not used often.
The double eccentric butterfly valve has the biggest application range.
The double eccentric effect is as follows. The reduction in the scratch phenomenon increases the application range of the 3PC ball valve BW in high temperatures. The triple offset 1PC ball valve is a torque seal. It solves the zero leakage problem of metal valve seat and the problems of resisting high pressure and high temperature.