This 4″ Sch 80 PVC Pneumatic Butterfly Valve, VITON, Single Acting, (FLANGE x FLANGE) is a butterfly valve with a pneumatic actuator on top for automatic control when compressed air is applied. the penumatic actuator opens when compressed air is applied to it but closes due to internal springs. 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.