| 摘要 |
Backflow preventer apparatus for preventing backflow of fluid in a fluid flow line includes an improved relief valve which drains fluid backflow from a zone between upstream and downstream check valves if the normal flow is shut off and downstream check valve fails to seal drip tight. During normal flow, the relief valve is closed. The relief valve includes a "peel seal" formed by a flexible diaphragm which peels to open the relief valve orifice for backflow therethrough from the downstream check valve to the ambient atmosphere.
|
