In the event of negative supply pressure such contaminated fluids will not backflow to the supply source by backsiphonage. 万一存在这种污染流体的反压力，则要避免由于反虹吸而回流到供应水源中。
This series is normally used in health hazard applications to protect against backsiphonage and backpressure. 这个系列通常用在健康危害应用场合保护不受反虹吸和反压力的损坏。
