Diaphragm for a breath-controlled dosaging valve

Claim 1

In a breath-controlled dosaging valve for use in gas mask and respirators of the type having a housing defining a chamber, a diaphragm, flexibly mounted to the housing, extending across the chamber and dividing the chamber into a first compartment open to the medium surrounding the housing and a second compartment, the second compartment having a first connecting socket for connecting the second compartment with a source of breathing gas and a second connecting socket for connecting the second compartment with a breathing circuit, shutter valve means for opening and closing a fluid communication path between the first connecting socket and the second compartment, a connecting lever connecting the diaphragm and the shutter valve means, and the shutter valve means being operative to open and close the fluid communication path responsive to the movement of the diaphragm, the improvement wherein the diaphragm is flexible and impermeable to gas in the temperature range of -70° C. and 80° C., and comprises an insert which is coated on each of its sides, an outer layer overlying said insert adjacent the first compartment and facing the surrounding medium comprising a silicone elastomer material, and an inner layer overying said insert adjacent the second compartment in a gas-tight relationship and facing the interior of the housing and exposed to the breathing gas, comprising a polypropylene oxide rubber material.