GB854194A - Improvements in or relating to warning devices for giving an audible signal when thepressure in a fluid pressure line has fallen to a predetermined level - Google Patents

Abstract

854,194. Respiratory appliances. SIEBE, GORMAN & CO. Ltd. Feb. 16, 1959 [May 7, 1958]. No. 14619/58. Class 81 (2). An audible warning device which operates when the gas supply pressure in a breathing apparatus has fallen below a predetermined level, includes an audible signal operated by gas from the supply under the control of a valve operable by a plunger responsive to the gas pressure, a first portion of the plunger being located in the pressure supply line, a second portion of the plunger being located exteriorly of the pressure line and being engaged by a loading spring, and a shank portion of the plunger between the first and second portions extending through a bore which is sealed by a joint ring at the surface of the shank portion. A body 1 with an axial bore 2 is connected at one end by a screw thread 3 to the gas supply and at the other end by a union 5 to a pressure gauge. The head 21 of a piston projects into the bore 2 from one side of the body, the shank 20 of the piston extending through a bore 19. The pressure of gas in the bore 2 presses the piston against a spring 27 which engages the shank 20 and is sealed from the bore 2 by a joint ring 23 surrounding the shank, the compression of the spring being adjustable by a threaded plug 29. Push rods 31 are supported by the piston and are located with large clearance in bores 13 which extend from the other side of the bore 2 into a space defined by a cap 36. In the event of the pressure of the gas supply falling below a predetermined amount the piston is pressed by the spring 27 so that the push rods 31 lift a valve member 32 in the cap 36 from its seat 33 against a spring 35. Gas from the bore 2 then flows to a whistle 37 by way of bores 13, the space in the cap and bores 15, 16 which are opened by lifting the valve member 32.