Patent GB-739823-A (GB)
Title: Improvements in or relating to breathing apparatus slide valves
Inventor: HAMILTON WILLIAM CRAIG
IPC: A62B9/02
Filed: 1954-01-18
Abstract: 739,823. Respiratory apparatus. MINE SAFETY APPLIANCES CO. Jan. 18, 1954, No. 1472/54. Class 81 (2). Respiratory apparatus is arranged so that the movement of a sliding member to release the regenerating cannister short-circuits the inhalation and exhalation passages and prevents the entry of the surrounding atmosphere. In the apparatus shown in Fig. 1 in which a face-piece 1 is connected via exhalation and inhalation tubes 4, 3, to a breathing bag 9 with associated removable air-purifying cannister 13 and slide valve means 11, exhaled air passes from the tube 4 through the valve means via its inlet 21 to the cannister where carbon dioxide is removed and oxygen added, the resulting gas mixture then rising through the valve means to the valve outlet 23 for passage into the breathing bag from whence it is inhaled through tube 3. On removal of the cannister 13 the valve means are as shown in Fig. 2, air entering the inlet 21 being diverted to the outlet 23. The valve means comprise an inverted cup-like housing 16 with inlet and outlet connections 21, 23, securely attached to an open-bottom annular shaped member 17, 29, the tubular part 29 being disposed longitudinally within the valve means and integrally attached to the ring-like part 1 by spokes 31. A valve seat 18 is formed on the upper surface of part 17 whilst slidable over the part 29 is a sleeve 28 formed with a lower outwardly-directed flange 27 and an upper inwardly directed flange 33, both sides of the latter flange being covered by sealing gaskets whilst the lower side only of the former flange is so covered. Slidable within the part 29 is a tubular member 43 pointed and provided with apertures 54 at its lower end. This member carries a spring 38 at its upper end and a valve disc 37 which carries a rod 39 slidable within a boss 41 depending from a spoke-like structure within the inlet 21 and which may engage the lower sealing gasket of flange 33. The upper sealing gasket of flange 33 may engage a valve seating 22 formed around the inlet 21. The sleeve 28 is pushed upwards against the action of a spring 32 by a funnel-shaped member 50 provided with four finger portions 57 which engage the lower surface of the sealing gasket below the flange 27, the member 50 being attached to the part 17 by a resilient ring 51. On attaching the new or newly-charged cannister, which has to be a particular type having concentric inlet and. outlet ports and depending tube 47, to the apparatus it is pushed upwards against the pointed member 43, the point rupturing the metal foil which generally seals it. The neck 48 of the cannister pushes member 50 upwardly causing the fingers 57 to press sleeve 28 against the valve seating 22. At the same time boss 41 arrests the upward movement of disc 37, thus opening the air connection between the inlet 21 and the cannister via member 43, apertures 54 and tube 47. Purified air then may pass from the cannister to the bag 9 through the member 50, the spokelike structure connecting 17 and 29, and the outlet 23. Connected between outlet 23 and inlet 21 is a diaphragm and valve structure such that if excess pressure should build up within the cannister it will be communicated by pipe 68 (see Fig. 3) to a diaphragm 67 which will cause a spring-loaded valve 73 to move from its seat 72 and let exhaled air pass from the tube 4 directly to the atmosphere through tube 63 and apertures 75.