Conduit blowout preventer

Abstract

The invention provides a conduit blow out preventer utilizing movement of an annular piston to selectively effect the reduction of flow through the blowout preventer to a pre-determinable value or alternately, terminate flow therethrough altogether in response to the occurence of a pressure fluctuation in the fluid conduit to which the conduit is attached. An annular fluid conduit is defined between the interior bore of the annular piston and a support post. A discontinuous annular sealing element is provided in such fluid passage to provide an orifice, creating a pressure differential across the piston in the event of a biased flow surge. Axial movement of the annular piston results in closing of the outward fluid flow in the annular fluid passage and flow is then restricted to that permitted by a radially disposed orifice communicating with the annular fluid passage. A check valve in a fluid inlet is normally held off its seat by a connecting rod extending to the support post. The support post is movable by the annular piston at the end of the annular piston movement to shift the support post sufficiently to permit the check valve to come into close proximity to its mating seat. The connecting rod may incorporate a mass of eutectic material which will melt in response to the temperature generated by a fire to permit the check valve to contact this mating seat to effect shut off of a biased fluid flow.