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|1. (WO2018141185) REDUCED-PRESSURE TYPE BACKFLOW PREVENTER|
|Applicants:||GUANGDONG YONGQUAN VALVE TECHNOLOGY CO., LTD
|Title:||REDUCED-PRESSURE TYPE BACKFLOW PREVENTER|
Disclosed is a reduced-pressure type backflow preventer, comprising a valve body (1), two check valves (2) which have the same structure and a drain valve (3). A cavity is formed in the valve body, and a water inlet, a water outlet and a drain opening are formed in a valve wall of the valve body; the two check valves are fixedly mounted in the valve body by means of a support pieces (4) and are located at the water inlet and the water outlet respectively; the drain valve is mounted outside of the valve body and is located at the drain opening; each check valve comprises a valve seat (201), a valve clack (202), a rocker (203) and twin torsional springs (204); one side of each valve clack is hinged to the upper end of the valve seat, and a roller (205) is mounted on the other side thereof; the rockers are connected to the lower ends of the valve seats by means of pin shafts (206); the rollers abut against the rockers and slide on the rockers; the pin shafts are sleeved thereon with the twins torsional springs; and the spring forces of the twin torsional springs act on the rockers to keep the valve clacks in a normally-closed state, and the rollers on the valve clacks are enabled to roll on the rockers by means of external forces so as to open the valve clacks. Owing to the twin torsional spring and rocker structures of the check valves, the reduced-pressure type backflow preventer achieves a better flow prevention effect.