This 3 inch double check detector assembly prevents the backflow of fire protection system substances from being pumped or siphoned into the potable water supply. It consists of a compact construction and short lay length, ideal for retrofit installations. It features a lightweight stainless steel body, thermoplastic and stainless steel check valves, and low head loss. It has outside stem and yoke shutoffs and a gallons per minute meter. It can be installed in a horizontal or vertical flow-up position. It is designed for installation on applications identified by local authorities as non-health hazard, such as on fire protection systems. The maximum working pressure is 175 PSI (12.06 BAR).