This 4 Inch Ames Deringer(Tm) 30 Double Check Detector Type II 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 30 Features 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. The Type II Bypass is Used to Monitor Unauthorized Water Usage, is Primarily Required on Fire Sprinkler Systems, And Comes With a Gpm Meter. Maximum Working Pressure is 175psi (12 Bar). | Apollo-Conbraco | AMD-4030-GPM