| 摘要 |
A device for the sampling and measuring of the concentrations of the gases expired by a person, comprising a "mediator" whose functioning may be overlapped, for what concerns the results, to the one that could be obtained by varying the capacity of a dynamic chamber, being (K)-times bigger, where (K=F/Fc), with (F) being the flow of the gas to be analyzed and (Fc) being the sampling flow. The sampling pump (4) is always in phase with the ventilation signal, and the capacity is always directly proportional to said ventilation according to a factor determined by amplifier (6) at variable gain and by power amplifier (5). When the ventilation signal increases, an integrator circuit (7) controls the gain of stage (6). This allows to vary the proportionality factor between ventilation and sampling flow of the pump. In this way the air volume passing through the mixing chamber (2) will be practically constant, and a functioning will be obtained being equivalent to the one of a dynamic chamber.
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