RPZ backflow preventervs double-check valve

Apollo 4ALF-20A-03 - 4", Stainless Steel, Backflow Preventer, Reduced Pressure Zone (RPZ) Assembly with OSY Gates, Lead Free

Apollo 4ALF-207-A2F - 1-1/2", Bronze, Backflow Preventer, Reduced Pressure Zone (RPZ) Assembly w/ Ball Valves, Lead Free

RPZ Backflow preventerdiagram

Apollo 4ALF-20G-03 - 10", FDA Epoxy Coated Ductile Iron, Backflow Preventer, Reduced Pressure Zone (RPZ) Assembly with OSY Gates, Lead Free

Apollo 4ALF-20C-03 - 6", Stainless Steel, Backflow Preventer, Reduced Pressure Zone (RPZ) Assembly with OSY Gates, Lead Free

Apollo 4ALF-200-03 - 3", Stainless Steel, Backflow Preventer, Reduced Pressure Zone (RPZ) Assembly with OSY Gates, Lead Free

Apollo 4ALF-209-03 - 2-1/2", Stainless Steel, Backflow Preventer, Reduced Pressure Zone (RPZ) Assembly with OSY Gates, Lead Free