| 摘要 |
A respirator 1 having a plurality of internal masks 2, 3 within an external mask 4, the inner masks 2, 3 being linked by ducts 8, 9 so as to direct the inhaled air from the outside of the mask to the oronasal area via an ocular mask. The oronasal mask 3 has a secondary valve 12 that is sprung so as to operate within the timeframe of the exhalation part of the breathing cycle, the exhaled air being ejected into the hollow outer body of the mask 4.
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