1. The backflow preventer is a device composed of non-return components that can prevent the backflow of water from the water supply pipeline.
2. Check valve refers to a valve whose opening and closing member is a circular disc and acts on its own weight and medium pressure to block the backflow of the medium.
1. The backflow preventer is divided into LHS743X low resistance backflow preventer and LHS743X backflow preventer according to the model. Divided according to the connection method: the flange connection has a decompression type backflow preventer, a low resistance backflow preventer (there is a dual-diaphragm low resistance backflow preventer, a single diaphragm low resistance backflow preventer); the threaded connection has Wire buckle type low resistance backflow preventer, miniature backflow preventer, water meter backflow preventer.
2. The check valve is divided into three types according to the structure: lifting check valve, swing check valve and butterfly check valve. Classified by material: cast iron check valve, brass check valve, stainless steel check valve, carbon steel check valve, forged steel check valve. According to function, DRVZ silent check valve, DRVG silent check valve, NRVR silent check valve, FSCV rubber flap check valve, DDCV double flap check valve.
1. The low-resistance backflow preventer is composed of two independent spring-assisted closed elastically-sealed check valves and an independent hydraulic differential drain valve in the middle decompression chamber. The pressure chamber of the drain valve is connected to the upstream water supply pressure. The three internal valves, except for the common valve body, have no mechanical connection (that is, no common related mechanical failures will occur at the same time), and ensure that each of them operates independently and strictly limits the pipeline. The pressure water in the medium can only flow in one direction.
2. Check valve This type of valve's function is to allow the medium to flow in only one direction and prevent the flow in the opposite direction. Usually, this kind of valve works automatically. Under the action of fluid pressure flowing in one direction, the valve disc opens; when the fluid flows in the opposite direction, the pressure of the fluid and the self-reclosing valve disc of the valve disc act on the valve seat to cut off the flow.