| 摘要 |
A U-shaped tube (12, 46) has an open end (18) and a closed end (20). An open-ended side tube (24, 48) communicates with the U-shaped tube (12, 46) adjacent the closed end (20), to establish a continuous passage (26) between the open end (18) and the side tube (24, 48). The device is used with a water cistern (30) having a tank (32), a siphon device (34, 50) and a ball valve (38) for establishing a normal water level (L). The open end (18) of the device (12, 46) is at a level below (L), and the side tube (24, 48) opens into the down-pipe (36, 56) at a level below (L). The U-shaped tube (12, 46) has its highest point positioned above the level (L). If the ball valve (38) fails, excess water passes through the U-shaped tube (12, 46) to be discharged into the down-pipe (36, 56). The water level is thereby regulated using no moving parts without effecting the efficiency of the flushing siphon. |
