| 摘要 |
A method and means for accurately regulating the rate of flow of supply gas to the burner or torch of a spectrometer. The flow rate is controlled by a valve having a closure member which is movable between a position at which it provides maximum obstruction to gas flow, and a position at which it provides minimum such obstruction. The closure member movement is controlled by a pulsed electrical signal so that the closure member moves rapidly and repeatedly between each of the two positions. Gas flow rate through the valve is therefore dependent upon the aggregate of the times the closure member spends in either of the two positions referred to, and that flow rate is changed by varying the frequency and/or pulse duration of the pulsed signal.
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