GB964787A - Improvements in or relating to breathing equipment - Google Patents

Abstract

964,787. Respiratory appliances. R. GALEAZZI. Oct. 27, 1960 [Oct. 28, 1959], No. 37015/60. Heading A5T. Breathing equipment comprises a plurality of cylinders containing different gases at the same pressure, the capacity of each cylinder being related to that of the other cylinder(s) in a predetermined ratio corresponding to the volumetric ratio of each gas in a breathable mixture to be formed and the cylinders being connected through conventional valves to a common conduit in which the breathable mixture is formed and which leads to a two-stage gas pressure reducer, and a breathing unit connected to the low-pressure side of the two-stage reducer. As shown, Fig. 1, nitrogen and oxygen are discharged respectively from cylinders 1 and 101, 201 into a mixing conduit 2 connected to a two-stage pressure reducer 4. The first stage, in which pressure is reduced to 18-22 atmospheres, comprises a nozzle 11 discharging into a chamber 12 into which a bored piston 14 extends. The unperforated lower end of the piston is urged towards the nozzle 11 and acts as a throttle valve when the pressure of gas on the upper face of the piston exceeds that of a spring 18 and of water entering the piston chamber at 17. A hole 117 in a second stage similar to the first stage may be closed by a plug 217. When the gas supply in the cylinders is nearing exhaustion, the pressure of gas through a by-pass 21 is insufficient to hold a valve 303 in the dotted line position against the pressure exerted by a spring 400 and by reduced pressure gas flowing into the valve chamber from an outlet 307. This gas therefore flows through a tube 24 to a bubble nozzle 124 near the user's face. In an alternative valve construction omitting the tube 306, the gas entering the by-pass 21 itself passes into the tube 24 when its pressure drops below a predetermined value. Low pressure gas is fed through a cock 6 with a passage 21 and an under-passage (not shown) to a distributing chamber 7 and mouthpiece 8. The chamber 7 through hoses 9, 109 is in communication with casing 10 in which carbon dioxide is removed from exhaled gases. To prevent the user breathing only re-circulated gases an extension 127 of the gas cock plug 27 carries an arm (not shown) which when the cock is closed, closes the valve 125 through which the re-circulated gases enter the chamber 7. In an embodiment, Fig. 7, in which there is only one hose connection between the chamber 7 and the casing 10, the gas cock comprises a chamber 6 having a valve seat 620 with one or more ports 626. A valve member 614 on a stem 606 may be rotated to bring a port 617 into register with the port 626 and returned in that position by engagement of a pin 602 in a groove 604. To prevent the user breathing when the cock is closed the mouthpiece 8 opens into a sleeve valve (not shown), closed when the gas cock is closed, against spring pressure, by a projection 623 on the stem 606. Liquid collecting in the chamber 7 may be blown out through a valve 706. Specification 964,788 is referred to.