Crew oxygen mask with pneumatic comfort adjustment

摘要

A respirator especially constructed for flight crews has a harness strap which can be inflated to a somewhat rigid, self-sustaining orientation to permit one-handed placement of the respirator over the wearer's head. Once the respirator is in place, release of a lever for inflating the strap deflates the latter to an orientation sufficient to cause the resilient strap to tightly press a peripheral seal of the respirator mask against nose and mouth areas of the user's face. A comfort adjustment to relieve strap tension permits selective reinflation of the strap to a somewhat smaller value than necessary for initial donning of the harness, and the limited reinflation pressure is sufficient for causing the mask to seal against the face during pressure demand breathing. In instances where pressurized breathing is needed, however, pressure within the strap is automatically released so that the strap presents sufficient bias to hold the mask against the face without oxygen leakage therepast.