GB266858A - Improvements in self-closing valves - Google Patents

Abstract

266,858. Blakeborough, R. A., Brotherton, C., Broadhead, J. B., and Edwards, G. T. Jan. 9, 1926. Valves controlled by pilot or relay valves. - A valve device adapted to close automatically with abnormal flow in either direction is controlled by the pressure or pressures derived from one or more Pitot tubes arranged in the main conduit but adapted to be withdrawn clear of the bore to permit the passage of a scraper. The main valve comprises a sluice valve with an eye to complete the conduit when the valve is in the open position, and is actuated by a double acting piston controlled by a four-way cock. The cock spindle c has a resetting handle j and a weighted arm c<3> adapted to rotate the cock and reverse the connections to the actuating cylinder when a projection c<4> on the lever normally engaged by a catch d<1> is withdrawn. The catch d<1> is formed on a weighted lever d having an arm e bearing on a diaphragm f. The chamber h beneath the diaphragm is connected to a Pitot tube pointing up stream while the chamber i above the diaphragm is connected to a corresponding tube pointing down stream. The Pitot tubes may be fitted with valves or connected to chambers provided with valves so that the chamber i is always connected to the downstream tube and the chamber i to the upstream tube whichever direction the fluid is flowing in the main conduit. The tubes enter the conduit through a member rand are adapted to be withdrawn into a housing s to leave the main conduit unobstructed. The tubes may carry a curved plate u to complete the conduit when these are withdrawn. The housing may be fitted with a shut-off valve t and carry a thumb screw v adapted to engage a slotted plate v<1> to hold the tubes in their raised position. A single Pitot tube with the orifice pointing either upstream or downstream may replace the double Pitot tube.