A personal breathing system incorporating a phased-dilution demand oxygen regulator (PDDOR) includes a pressurized oxygen source and oronasal mask, a dilution valve for supplying ambient air and a demand valve for supplying pure oxygen. The PDDOR senses the mask pressure associated with the start of an inhalation cycle, maintaining pressure to the demand valve through an initial demand phase during which 100% pure oxygen is supplied through the demand valve. Control pressure within the PDDOR drops throughout the initial demand phase; when the pressure drops below a lower threshold the PDDOR main valve is closed, blocking the demand valve and cutting off the oxygen supply. Ambient air is provided to the mask via a dilution valve to preserve flow to the user.

There is disclosed a valve assembly for a lung demand regulator of a breathing apparatus. The valve assembly comprises a regulator valve apparatus for regulating a flow of breathing gas, the regulator valve apparatus being actuatable between a closed position in which no flow is permitted and an open position in which flow is permitted. The valve assembly further comprises a lockout mechanism configurable in: i) a lockout configuration in which the regulator valve apparatus is secured in the closed position, and ii) a release configuration in which the regulator valve apparatus is freely moveable. The lockout mechanism comprises an axially compressible spring element. The lockout mechanism is configured such that the spring element is axially compressed during movement of the lockout mechanism between the release configuration and the lockout configuration. Also disclosed is a lung demand regulator and a breathing apparatus comprising a lung demand regulator.

Disclosed is a modular serviceable cartridge assembly for a respirator exhalation unit that is simple in construction and that allows quick-connect of an exhalation valve cartridge in a mask to minimize the need for reconfiguration when changing personal protective equipment, and that allows for easy removal and breakdown for servicing and/or replacement of individual components of the exhalation valve without modifying or replacing other elements of the protective mask. The assembly may be convertible from a negative pressure valve assembly to a positive pressure valve assembly, and vice versa, and a grill may be provided on an outlet side of the cartridge assembly, the rotation of which converts the assembly from a negative pressure valve to a positive pressure valve.

A demand regulator (1) for aircraft breathing device (100) comprising: a respiratory chamber (9) supplied with respiratory gas comprising breathable gas and dilution gas, a breathable gas supply line (12, 13), a dilution gas supply line (14, 15), a first adjusting device (50, 60) of non-electrical type adjusting the pressure in the respiratory chamber (9), and a second adjusting device (22, 24, 40, 41-49) adjusting the rate of dilution gas in the respiratory gas supplied to the respiratory chamber (9), the second adjusting device comprising a dilution valve (24) disposed in the dilution gas supply line (14, 15), a sensor (41-49) and an electrical control unit (40) adjusting the rate of dilution gas in the respiratory gas by controlling the dilution valve (24).

Disclosed is a modular serviceable cartridge assembly for a respirator exhalation unit that is simple in construction and that allows quick-connect of an exhalation valve cartridge in a mask to minimize the need for reconfiguration when changing personal protective equipment, and that allows for easy removal and breakdown for servicing and/or replacement of individual components of the exhalation valve without modifying or replacing other elements of the protective mask. The assembly may be convertible from a negative pressure valve assembly to a positive pressure valve assembly, and vice versa, and a grill may be provided on an outlet side of the cartridge assembly, the rotation of which converts the assembly from a negative pressure valve to a positive pressure valve.

An oxygen system supplies either 100% oxygen to a demand valve in the a mask or pulses of oxygen to the mask. Switching is automatic during a parachute descent. The system includes a valve manifold that is responsive to ambient pressure such that at low pressures it is configured to deliver gas from either an oxygen cylinder or an aircraft supply line to the mask demand valve and at higher pressures it is configured to deliver gas from the cylinder to a pulse gas delivery system. The mask also includes an inhalation valve that is closed if oxygen is supplied to the demand valve. Otherwise, the inhalation valve opens to allow ambient air to be drawn in and the pulse gas delivery system delivers a pulse of oxygen in response to the onset of inhalation.

A diaphragm for a lung demand valve, including a CBRN layer which is sufficiently resistant to the permeation of at least some CBRN agents and a resilient layer which is resiliently deformable. The CRBN layer is arranged to restrict the permeation of at least some CBRN agents through the diaphragm, and the resilient layer is arranged to allow the diaphragm to be resiliently deformed.