| 摘要 |
The breathing system comprises a canister carrying layered filtering material, including activated carbon granules, a dessicant, a catalyst for the catalyzation of carbon monoxide to carbon dioxide, optionally lithium peroxide, for conversion of CO2 to O2, and electrostatically charged filters between the layers of filtering material. A mouthpiece carrying a noseclip, and inhalation and exhalation check valves and a whistle is disposed within a flexible, substantially completely transparent hear-through hood, both the mouthpiece and hood being disposed in the canister between the filtering material and a cover for the canister. In use, the cover is removed, air inlet apertures are uncovered, and the hood is drawn about an individual's head and substantially sealed about the neck. With the mouthpiece in the individual's mouth, and noseclip closing off the user's nose, inhalation causes air to flow through the filtering material and the inhalation check valve and past the exhalation check valves. When exhaling, the exhalation check valves open to permit exhaled air to flow into the hood. The inhalation valve closes during exhalation to prevent backflow of air through the filtering material. By exhaling into the hood, a slight positive pressure within the hood is established to prevent noxious gases, smoke particles and the like from entering the hood through the neck opening. A chemical light is provided externally on the canister.
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