| 摘要 |
PROBLEM TO BE SOLVED: To provide a backflow prevention device which smooths a motion of a valve body by suppressing resistance of contact between the valve body and a guide part and which does not structurally cause a malfunction even when rapid back-flow water abuts on the valve body.SOLUTION: A backflow prevention device 1 includes a valve body 11 which is operated by drainage and the like from a downstream side. A guide part 4 for guiding a motion of the valve body 11 is suspended from the center of an undersurface of a body part 2. In the guide part 4, a total of four protrusions 5 is provided on an outer periphery from its midpoint to a lower end. During the operation of the valve body 11, since the valve body 11 and the guide part 4 abut on each other only via the protrusions 5, the valve body 11 can be operated without being disturbed by resistance, even when the resistance such as surface tension occurs on the valve body 11. |
