| 摘要 |
PROBLEM TO BE SOLVED: To make a check valve smoothly open even when drain water in initial drainage flows down from an outer periphery of a drain pipe in a drainage system using the check valve, and to improve a drain flow rate in the drainage system using the check valve.SOLUTION: In a drainage system comprised of a drain pipe 2 and a check valve 3 provided with a valve body 34 structured and disposed in the drain pipe 2, always blocked-up, and opened when drainage occurs, a throttle mechanism 5 with a cross-sectional area narrowed by reducing the inner diameter of the drain pipe 2 is constituted on the upstream side of the check valve 3. |
