| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a backflow prevention device capable of preventing backflow water from reaching a water supply source side even when a reverse jet flow is generated in a check valve on a downstream side. <P>SOLUTION: A backflow prevention device 10 related to this embodiment includes a first check valve 11, a negative pressure destruction valve 15 and a second check valve 13 installed in order from a primary side on a flow path 19. The negative pressure destruction valve 15 has a function of being opened to the atmosphere as a pressure on the primary side of the first check valve 11 lowers and discharging backflow water flowing back through the second check valve 13, and further includes a partition 18 formed between the first check valve 11 and the second check valve 13 such that, even when a reverse jet flow which is the jet flow of the backflow water is generated from the second check valve 13, the reverse jet flow does not directly reach the first check valve 11. The first check valve 11 is installed at an upper part so that the backflow water by the reverse jet flow does not reach the first check valve 11 even when it further flows to a lower part by gravity. <P>COPYRIGHT: (C)2013,JPO&INPIT |
