| 摘要 |
<p>PURPOSE:To achieve highly accurate calibration by executing calibration only when the difference of two values of the flow rate continuously measured in the fluidic state is not larger than a predetermined value in the case where the to-be-measured flow rate is in the overlapping range. CONSTITUTION:The intermediate-large flow rate is measured by a fluidic oscillating device 1, while the small flow rate is measured by a thermal flow sensor 4. At the same time, there is arranged an overlapping range where the measuring ranges of the flow rate are overlapped. In the case where the to-be- measured flow rate is in the overlapping range, flow rates Qn-1, Qn of the first time and the second time are measured continuously by the fluidic oscillating device 1. The change of the flow rate is detected from the second measured value. Only when the difference of the measured values is not higher than a predetermined value, e.g. when the difference is not larger than 5%, the thermal flow sensor is calibrated. It is favorable that the calibration is completed within one minute. In this manner, the calibration with high accuracy is achieved even when the measuring time is shortened.</p> |
