máscara de respiração com redução do consumo de oxigênio

Embodiments of the invention provide a breathing mask for aircraft crewmember. The breathing mask includes an on-demand regulator with an inlet connected to a source of breathing gas and an outlet to exhaust the breathing gas. The outlet has an aperture controlled by a movable valve having an open position when the crewmember breathes out and a closed position when the crewmember breathes in. The breathing mask also has a latch member operable by a crewmember to latch the valve in the open position, the latch member including an unlocking member to release the valve when the cabin pressure is below a predetermined value.