Series 3000B Double Check Detector Assembly is designed exclusively for use in accordance with water utility authority containment requirements. It is mandatory to prevent the reverse flow of fire protection system substances, i.e., glycerin wetting agents, stagnant water and water of non-potable quality from being pumped or siphoned into the potable water line. The Series 3000B is ideal for use on non-health hazard fire protection systems to detect leaks or unauthorized water usage.