| 摘要 |
PROBLEM TO BE SOLVED: To secure a backflow prevention function over a long period, by preventing electric erosion of a constituting member such as a backflow preventing float in a drain pipe, in a floor drain funnel used under an environment n which a waste liquid and a backflow liquid include an electrolyte such as seawater, for example, in a nuclear power plant building.SOLUTION: A cutoff member 21 having a valve seat member 8B is provided in a drain pipe 6 of the floor drain funnel, and a communication hole 8a is formed in the valve seat member 8B. A float 14 is provided inside the drain pipe 6 on the lower side than the cutoff member 21. The valve seat member 8B include a rubber layer and a resin layer such as Teflon (Registered Trademark) superposed on the upper side of the rubber layer. |
