This 4 Inch Ames Deringer(Tm) 20X Low Head Loss Double Check Valve Backflow Preventer Assembly is Designed to Prevent Non-Health Hazard Pollutants From Entering The Potable Water Supply System Caused by Backflow Due to Backpressure And/Or Backsiphonage Conditions. Deringer 20X Features Extra Large Body And Checks For Lower Head Loss, Integral Eccentric-Seal(Tm) Butterfly Shutoff Valves For a Short Lay Length, Integrated Tamper Switches, And Dual-Action(Tm) Checks For High Performance at Low-And High-Flow Rates. It May be Installed Under Continuous Pressure Service to Protect Against Both Backpressure And Backsiphonage. Maximum Working Pressure is 175psi (12 Bar). | Apollo-Conbraco | D-4020X