GB827481A - An improved pressure relief valve - Google Patents

Abstract

827,481. Relief valves. LAMB PUBLICATIONS & INVENTIONS Ltd., J. March 18, 1958 [April 16, 1957], No. 12378/57. Class 135. A disc 4 of a relief valve for electric furnaces &c. is attached to a plunger 6 which is slidable within a cylinder 14 and has an extension 26 for operating a valve, such as a spring-closed ball valve 27, to control the admission of loading air to the cylinder to close the relief valve, and means, e.g. shuttle valve 23, sliding between shoulders 21, 22 on a hollow part of the plunger to control the radial ports 24, and radial ports 25 controlled by the position of the plunger in the cylinder are provided to delay the action of the loading air to enable the relief valve to fully open. An inner extension of the plunger may be guided by a spider 8, attached to the wall of the furnace, and may be shielded by tubular members 11, 12, 13. In the event of an explosion as the valve disc lifts, the shoulder 22 of the plunger abuts the shuttle valve 23 to allow air admitted to the cylinder by the plunger extension 26 displacing the ball 27 to escape freely to atmosphere via ports 24, the tubular part of the plunger and ports 25. When ports 25 are covered by the cylinder wall, pressure builds up in the cylinder at first to arrest motion of the valve disc and thus force it to its closed position: at this time the shuttle valve 22, due to friction with the cylinder wall, is abutted by shoulder 21 and the outlets 24 are closed until the valve disc again reaches the closed position shown. As described, the furnace works under vacuum and the valve disc is held closed by the pressure difference, but a spring of suitable strength may be added to hold the valve disc closed under normal working conditions where a positive pressure exists in the furnace.