Safety valve

Claim 1

In a safety valve, the combination of a valve body defining a valve chamber having a fluid inlet and also having a fluid outlet port, a main valve member movable in said chamber and resiliently biased to a position wherein said outlet port is normally open, said main valve member being movable into engagement with the outlet port to close off the same from said chamber when a substantial fluid pressure differential across the valve exists, said main valve body also being provided with a restricted bypass passage extending from said chamber into said outlet port, a by-pass valve provided in said body and normally closing said bypass passage, said by-pass valve being manually openable to effect a substantial balance of fluid pressure across the valve and return said valve member to its position in which said outlet port is open, and means for preventing removal of said by-pass valve from said body when the by-pass valve is opened, said valve body having an outer surface and being formed with a bore extending inwardly from said outer surface to an intersection with said by-pass passage, said bore having a screw-threaded outer end portion, said by-pass valve comprising a screw adjustably engaging the threaded outer end portion of said bore, said screw being adjustable between a screwed-in position wherein it closes said by-pass passage and a screwed-out position wherein the by-pass passage is open, said removal preventing means being effective to prevent screwing-out of said screw from said bore, and said removal preventing means comprising a keeper screw threaded into said valve body at a point adjacent said bore, said keeper screw having an enlarged head the underside of which overlaps said bore and prevents screwing-out of said by-pass valve screw from the bore.