Frostproof backflow preventer
US4117856A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 27, 1976 |
| Grant date | Oct 3, 1978 |
| Priority date | — |
| Expiry date | Sep 27, 1996 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T137/9029
- WIPO fieldMechanical elements
- WIPO sectorMechanical engineering
Abstract
A backflow preventer in a fluid conduit permits flow from the inlet to the outlet of the preventer when the inlet is pressurized and prevents reverse flow upon termination of flow through the preventer. An apertured diaphragm between the inlet and outlet closes a valve seat between the outlet and a vent passage when the inlet is relatively pressurized. A check member upstream of the diaphragm closes the diaphragm aperture if the outlet is relatively pressurized and maintains the diaphragm aperture closed upon pressurization of the inlet until after closing of the vent valve seat. A second vent communicates with the interior of the preventer and is closed by a portion of the diaphragm upon pressurization of the interior. A relief port in the chamber includes a temperature responsive element that opens the relief port once ambient temperature reaches a preselected level. The inlet includes an internally threaded sleeve within the housing that may be secured to an externally threaded fluid hydrant. The sleeve allows the preventer to be attached to a hydrant, but prevents its removal after a key in the sleeve is removed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.