The Deringer 20 (DC) 2″ Double Check Backflow Preventer is a reliable and efficient solution designed to protect potable water supplies from contamination caused by backflow. Engineered with precision and built to meet stringent industry standards, this backflow preventer ensures the safety and purity of water in various applications.

This total rubber parts kit is used for replacing or repairing the relief valve assembly on a 4 inch lead free reduced pressure zone assembly series 909 used to prevent the reverse flow of polluted water from entering into the potable water supply due to backsiphonage and or backpressure. This kit consists of a diaphragm, two molded disc assemblies, two seat O-rings, RV O-ring, two piston O-rings, RV stem O-ring, flow tube O-ring and cover O-ring.