This 4" double check detector backflow preventer 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 a gallon per minute meter. The connections are grooved inlet x grooved outlet. 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).