KLAPPENVENTILANORDNUNG UND VERFAHREN ZU DEREN HERSTELLUNG

摘要

A butterfly valve assembly of plastic material for use in a plastic piping system. The valve body is made from thermoplastic wherein the valve seat has a hard core of phenolic or another plastic and a resilient cover. The plastic valve body utilizes a retainer ring in its construction to maintain pressure on the valve seat which aids in sealing the valve closure thereagainst. The closure disc may be of metal or plastic depending on the service contemplated. The closure disc is retained in the valve body by a lower valve stem which is affixed in the valve body to permit free rotation of the closure disc thereon and an upper valve stem which includes a central retainer ring and is supported by a housing on the valve body. The housing has a bushing that seats against the retainer ring and a tubular plug which seats in the housing exerting pressure against the bushing, and thus, against the central retainer ring to assist in blow-out protection. The tubular plug is sealed by an internal o-ring to the upper valve stem. The upper and lower valve stems are sealed to the hard core body of the valve seat. The valve seat is sealed in the valve body by a pair of o-rings on opposite sides of the valve stems. The upper valve stem is keyed to rotate the closure disc by a handle arrangement. The valve is operable through 360 DEG range and has a locking pin to hold the valve fully open, or fully closed, or at various intermediate positions. The valve may be installed in either direction in a piping system.