GB488666A - Improvements in and relating to regenerative breathing apparatus for protection against fumes, powders and noxious gases - Google Patents

Abstract

488,666. Breathing apparatus. REGNAULT, H. A. M. Jan. 19, 1937, No. 1643. [Class 81 (ii)] In regenerative breathing-apparatus, wherein a regenerator cartridge, replaceably held in a casing, contains oxygen-generating material, such as a mixture of oxylith and pumice powder, and also carbon dioxide absorbent such as soda-lime, means are provided for passing a predetermined proportion of the exhaled air through the first material and subsequently through the second, and for passing the remainder through the carbon dioxide absorbent only. As shown, the cartridge 18, Fig. 8, enclosed in a casing 13 and having oxylith-pumice mixture enclosed between gauzes 24, 25, and soda-lime above the gauze 25, is provided with a tube 29 immediately beneath, but spaced from the cartridge inlet 7, by an amount fixed by soldering the tube to the gauzes, a dual path, respectively through both materials, and through the soda-lime only, being thus provided, to the exit tube 8 for the respired gases. Gauzes 31, 32 surround the tubes 7, 8. The casing 13 is open at the bottom for the insertion of the cartridge and is perforated on its upper surfaces and provided with a corrugated metal liner at 17 to assist cooling. The cartridge is sealed by metal discs 33, ruptured by teeth 15 on the tubes 7, 8, on insertion into the casing, and is held in place by a bail 19 engaging a bridge piece 14a, one of these being resilient. The cartridge may also be held before unsealing in a lower position by a lug on the front wall thereof engageable with an indentated leaf spring mounted on the inner wall of the casing and retractable by an external knob. The apparatus described is used in connection with a gas-proof upper garment 1, Fig. 1, having a windowed head covering 2 mounted over a wire frame 3 resting on the shoulders, and sealed at waist and wrists. The tube 8 communicates with a breathing- bag on the back or with the interior of the garment which serves as a breathing-bag, and in the latter case contains a spring closed valve with a tail-rod 35, Fig. 8, engaged by the canister on insertion to hold the valve open. Alternatively the tube 8 contains a handoperable cock 37, Fig. 1. Tube 7 receives exhaled air through a tube 12 within the garment, connected to the mouth and containing a non-return valve. The garment carries near the mouth an air-filter 6 communicating with the atmosphere. When the canister is not in operative position tube 8 is closed by the spring valve or by the cock 37, and the wearer can inhale through the filter 6, and exhale through the valve in tube 12, and tube 7.