LHS743X low drag shape material backflow prevention device is the use of ductile iron, stainless steel 304; product structure: the front two automatic drain valve and the intermediate composition before and after the non-return valve in the leakage generated when the check valve in the front to automatically drain, blocking back, and strictly prevent backflow pollution, protect water quality upstream pipeline. One, LHS743X low resistance backflow prevention device following advantages: First, the use of low-drag design with low water loss, head loss is less than 0.03Mpa, so the product is very energy efficient; Second, to achieve the air cut off, self-draining operation in the project If reflux occurs when the main valve is closed, the drain can automatically open, intermediate chamber vent pressure is zero, the main valve can be achieved between the upstream and downstream partition or zero air pressure cut off, thereby blocking reliable performance; Third, due to product volume than small, the installation more flexible, smaller than HS41X antifouling cut off valve is very much in the project which can be installed horizontally or vertically; Fourth, the product material used: ductile iron coated inside and outside surfaces of powder coating spray paint thermoforming , the coating thickness is not less than 250μm. Two, LHS743X low resistance backflow prevention device Product parameters: Nominal pressure: 1.0Mpa; 1.6Mpa; opening pressure: ≤ 0.03Mpa; local head loss: ≤ 0.03 Mpa; partition forms: air partition or zero pressure cut off; Body Material: ductile cast iron, 304 stainless steel; Trim Material: 304 stainless steel; Suitable temperature: ≤ 65 ℃. Three, LHS743X low resistance backflow prevention device operating principle: LS743X low resistance backflow prevention device uses advanced structural design, is the use of hydraulic control (valve) principle, the use of pressure backflow prevention device with a completely different control methods, either air is cut off to ensure that the form of the highest security level of the partition, but also effectively reduce head losses in the flow velocity V = 2.5m / s, the head loss h = 2 ~ 3m; small dimensions, may be horizontal or vertical installation Basically, to achieve the ideal backflow prevention device requirements. Four, LHS743X low resistance backflow prevention device main application areas: LHS743X low resistance backflow prevention device is mainly used for: urban water supply network, water companies and the various types of pipe network users, or between the drinking water and in water (the product of their health Security meets drinking water standards GB/T5750, attached to drinking water safety product inspection reports), fire water, air conditioning, water, green water, water systems and other heterogeneous cross-connection between the effective partition, or vacuum equipment supporting the installation , can strictly prevent backflow contamination. Five, LHS743X low resistance backflow prevention device installed Analysis: 1 - before the control valve 2-Y-type filter 3 - Low resistance backflow prevention unit 4 - flexible rubber connector 5 - After the control valve 6 - drainage outlet 7 - floor drain 8 - Bracket