| 摘要 |
PURPOSE:To always keep a blend ratio of both gases at a prescribed value by converting a detecting pulse of a low frequency to a high frequency of some multiple times so that a volume deviation of both fluids can be brought to a measurement control instantaneously. CONSTITUTION:When frequencies of the respective output pulses from detectors 12, 22 are denoted as f1 and f2, respectively, flow rates Q1, Q2 of the first and the second fluids are shown by Q1/Q2=f1/f2. Also, periods T1, T2 in period measuring parts 45, 46 become T1=1,000n/f1 and T2=1,000n/f2, respectively, and a difference DELTAf between a pulse f(+) of a (+) side of a reversible counter 49 and a pulse f(-) of a (-) side becomes DELTAf(+)-DELTAf(-)=f0(f1.X-f2)/1,000n, when a set value of a blend ratio setting device 42 is made X%. In this case, f0 is an oscillation frequency of an oscillator 41. In this way, a pulse of a low frequency generated from the detectors 12, 22 is converted to a pulse of a high frequency and measured, by which an operation of a counter 49 is executed quickly, and a responsiveness of a blend becomes quick. |
