Dual-seal sprinkler system

Claim 1

In a sprinkler comprising a frame formed at one portion with a fluid passage terminating at an annular seat, a closure disposed across said passage adjacent said seat, an annular seal having a pressure-impacted side and another side exposed to ambient pressure and being disposed between said closure and said seat, and means disposed between another portion of said frame and said closure so as to hold said closure with said seal when said means is at ambient temperature and adapted to release said closure and said seal when said means is at elevated temperature, an improvement wherein said seal comprises a sealing membrane of deformable sheet-like film material and having its periphery lying against said seat and also having an annular portion adjacent the periphery trasversing a portion of the passage and lying against the closure, and a compressibly elastic sealing ring disposed between a portion of said closure and the periphery of said sealing membrane, the closure bearing against said elastic sealing ring which resiliently presses the periphery of said annular sealing membrane against said seat to require the film material of the membrane to conform to the contour of the seat and seal thereagainst, said sealing membrane forming the pressure-impacted side of the seal and the annular portion of the membrane also traversing the elastic sealing ring and isolating the ring from the passage and the fluid therein.