| 摘要 |
There is disclosed an emergency breathing apparatus that provides a sustained life support for a period of time up to about 30 minutes and that is useful for fire fighters and the like in a hostile environment. The device comprises a harness with a backpack air supply cylinder provided with a shut-off valve and pressure regulator at the cylinder. The regulator has a bypass connection for attachment of a remote pressure sensor and a valve which opens when the pressure declines to a predetermined value and applies regulated air pressure to an audible warning device such as a whistle, buzzer, bell and the like. The device employs a pilot regulator on the mask which is a very compact and simple structure with only a few moving parts, and consequently, easier to manufacture and maintain than more bulky, complicated structures of the prior art. The pilot regulator is provided with a manual switch to change its operation from demand to pressure demand so that the mask can be donned in the demand position without a continuous loss of air and thereafter switched to the pressure demand mode to provide a continuous, regulated supply of air to the user.
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