Series 806YD DuraCheck In-Line Design Double Check Detector Assemblies prevent the backflow of pollutants that are objectionable but not toxic, from entering into the potable water supply. They are used primarily on fire sprinkler and standpipe systems requiring detection of unauthorized water use. They feature a ductile iron body and stainless steel spring assemblies for corrosion resistance. Maximum Working Pressure: 175psi (12.1 bar).