This 4″ Sch 80 PVC Butterfly Valve, VITON, (FLANGE x FLANGE) opens and closes to stop flow with a quarter turn of the handle. The disk inside the valve remains inside the flow path causing a larger pressure drop than copmarable ball valves. Butterfly valves are installed between a pair of flanges with falnge bolts. No gaskets are required, they are built into the valve face. Sch 80 PVC is robust and durable, perfect for commercial and industrial applications. VITON seals provide increased temperature resistance than EPDM seals and recommended for exposure to oils, gasoline and aggressive chemicals. Have a question? Check our technical resources section or give us a call and take advantage of our years of experience.