Patent ID: 8215303

Claim:
A lung demand valve device for use with breathing apparatus, for delivering breathable gas from a pressurized supply to a user wearing a face mask, for inhalation, the device comprising: a body in which is housed a valve member, for controlling the rate of delivery of the breathable gas, a housing within which is mounted a movable diaphragm having a first face exposed to pressure within the body and a second face exposed to pressure outside the body, the diaphragm being responsive to the differential in pressure between its first and second faces to control an actuation arm of the valve member, wherein the housing comprises a base having at least one hole therein which is positioned away from the second face of the diaphragm, and a duct arranged to direct exhaled air past and around said second face of said diaphragm through the at least one hole in the base, wherein the duct comprises: a rigid duct portion attached to the housing and arranged to abut an outlet port of a face mask; and a flexible cover portion which extends between the housing and the rigid duct portion, and over the base, thereby preventing the ingress of dirt into the housing.