MASS FLOWMETER AND MASS FLOW CONTROLLER

摘要

PROBLEM TO BE SOLVED: To improve the measurement accuracy of a mass flowmeter by correcting measurement flow rate, using not only a coefficient which is determined in accordance to gas species, but also correcting the measurement flow rate by using the primary-side pressure.

SOLUTION: This flowmeter includes a flow rate computing part 42 or computing the flow rate Qrawof a sample gas G, by acquiring the output signal from sensor parts 411, 412 having thermosensitive resistors 41a, 41b set at the flow passage where the sample gas G flows; a pressure-measuring part 43 for measuring the primary side pressure Pinat the flow passage 2; and a flow rate correcting part 44 for correcting the measurement flow rate Qraw, obtained by the flow rate computing part 42 by using the primary-side pressure Pin, obtained by the pressure measuring part 43 and a gas coefficientαwhich is determined by the constant pressure specific heat Cpof the sample gas G.

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