Flapcon® BV40 series Double Flanged type butterfly valves are manufactured from Ductile Iron, Steel and Stainless Steel castings. The BV40 Series with concentric design and vulcanized rubber gasket material options are manufactured to be compatible with many fluids . Vulcanized gasket design provides extra strength against granular abrasive fluids. Due to its high permeability, it is preferred over large diameter lines. It can be used at the end of line with one side flange connection.