| 摘要 |
526,792. Valves. GROENIGER, W. C. June 1, 1939, No. 16198. [Class 135] Siphoning back in water or other supply systems, due to the formation of vacuum therein, is prevented by a valve device comprising a flap valve 20 hinged at 21 so as to control the main supply passage 11, 17, 13, and a second valve 32 attached thereto and adapted, when the valve 20 is opened by the flow of water, to close an air vent 25. If vacuum forms, air enters past the valve 32, and the valve 20 is closed. |
