GB1297305A - - Google Patents

Abstract

1297305 Breathing masks; valve and speaking diaphragm unit MINE SAFETY APPLIANCES CO 6 March 1970 [29 April 1969] 10881/70 Heading A5T A breathing mask comprising an air inlet, and a nose cup having an air outlet is provided with a valve and speaking diaphragm unit in fluid communication with the said inlet through an inhalation valve, and with the said outlet through an exhalation valve. As shown, the nose cup 2 has an outlet 4, and inlet passages 6 of the mask are in communication with the inside of an open tube 10 via an opening 11 in the walls of the tube diametrically opposite a speaking diaphragm 16 in a second opening. A second tube 17 is sealed at one end around the diaphragm 16 and extends transversely to the tube 10 through the opening 11 and is spaced from the walls of a flange 12 mounted around the opening 11 but connected to the flange by walls 18, 20. The flange 12 has an opening 14, and the second tube 17, an opening 19 such that the inlet passages 6 are in communication only with one end of the tube 10, while the outlet 4 is in communication only with the other. An inhalation valve 23 is placed inside the end portion of the inlet portion of the tube 10 and an exhalation valve 22, inside the other end portion. Each of the valves comprises a generally cylindrical cup 25 with a base 26 with an opening 28 over which is placed a flexible flap 33, within the body for an exhalation valve and outside it for an inhalation valve. Ribs (35)-(37), Fig. 6 (not shown), are provided extending longitudinally over the surface of the cup 25 and are adapted to fit into grooves in the inside of the tube 10, the cups of either type of valve being initially identical. A rib of the exhalation valve 22 is removed prior to insertion and one of the inhalation valve 23 is also removed, this rib being in a different position on the body 25 to that removed from the valve 22, corresponding grooves of the tube 10 being placed so that the valves may not be inserted into the wrong ends.