| 摘要 |
<p>PURPOSE: To inform the generation of backflow in a distribution system connected to a drinking water source and provided with the structure for preventing the pollution of the fluid source by the backflow of the dangerous liquid by providing an alarm unit to be operated when a discharge port of a relief valve is opened. CONSTITUTION: A housing 12 is provided with an inlet 14 connected to a fluid source in the upstream, an outlet 16 connected to a distribution system in the downstream, a discharge port 18, a first check valve 20 for opening and closing a flow passage between the inlet 14 and the outlet 16, and a second check valve 22 for opening and closing a flow passage between the first check valve 20 and the outlet 16. Furthermore, a relief valve 40 to be switched between the closing condition and the opening condition is provided between the first and the second check valves 20, 22, and the outlet 16 and the discharge port 18 are communicated with each other when the relief valve 40 is opened. In the condition that the relief valve 40 is opened, an alarm means including a plunger 80, a switch 82 and an audible alarm unit 92 and connected to the relief valve 40 is operated so as to inform the generation of backflow.</p> |
