| 摘要 |
PURPOSE:To enable measurement over a long period of time even under an adverse high temp. environment containing a large amount of dust in an inexpensive and durable system, by calculating the difference of the time constants of two thermometers different in responses while measuring a flow speed from the relation of the difference of time constants preliminarily calculated on the basis of the difference of said time constants and the flow speed. CONSTITUTION:The outputs of thermometers 10, 12 respectively having different constants T1, T2 are converted to temp. detection values Tm1(t), Tm2(t) by a temp. converter 4. When the temp. Tf(t) of a fluid shown by the arrow X is changed, the difference E of detection values caused by the difference of response speeds is generated between Tm1(t) and Tm2(t) and this differential pressure E is calculated by a subtractor 16. The linearity in the change in the temp Tf(t) of the fluid is judged by a linearity judging and detecting mechanism 18. When the change is linear, the gradient (a) of the straight line is calculated by an inclination operator 20. The gradient (a) of the linear change of the detected value is inputted to a dividing device 22 to operate time constant difference DELTAT=E/a. Vf is calculated from DELTAT on the basis of the relation of the preliminarily calculated difference of the flow speed and time constant by a flow speed operator 24.
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