| 摘要 |
An oxygen system and mask (9) for use in parachuting are described. The system supplies either 100% oxygen to a demand valve (6) in the mask (9) or pulsed delivery of oxygen to the mask (9). Switching is achieved automatically during a descent, thus conserving gas and at the same time reducing the likelihood of error. The system includes a valve manifold (3) that is responsive to ambient pressure such that at low pressures it is configured to deliver gas from either an oxygen cylinder (1) or an aircraft supply line (10) to the mask demand valve (6) and at higher pressures it is configured to deliver gas from the cylinder (1) to a pulse gas delivery system (212). The mask also includes an inhalation valve (7) that is closed if oxygen is supplied to the demand valve (6). Otherwise, the inhalation valve (7) opens to allow ambient air to be drawn in and the pulse gas delivery system (212) delivers a pulse of oxygen in response to a pressure drop inside the mask, which indicates the onset of inhalation. |
