| 摘要 |
The oxygen breathing system with programmed oxygen delivery comprises a breathing circuit which a user exhales into and inhales from and a source of oxygen which delivers oxygen to the breathing circuit at a programmed rate. The oxygen is supplied at a high rate during the initial period of operation and at a low rate during the remaining period of operation. An overpressure relief valve in the breathing circuit opens during the initial time period because of the high oxygen delivery rate thereby flushing from the breathing circuit the nitrogen initially residing in the lungs of the user and in the breathing circuit. As a result of the flushing, the oxygen content in the breathing circuit approaches 100 percent at the end of the initial period and remains near this level during the subsequent time period. The source of oxygen can be a chemical reaction which occurs when a chemical compound is combined with a liquid in which case the programmed oxygen delivery is achieved by metering the liquid that is added to the chemical compound. Alternatively, the source of oxygen can be a storage container of oxygen or a contained chemical reaction and the programmed oxygen delivery is accomplished with a valve having a programmed flow rate.
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