Patent ID: 8356623

Claim:
A mass flow meter comprising: a flow rate calculating section that obtains an output signal from a sensor section having a thermosensitive resistive element arranged in a flow channel where a sample gas flows, and that calculates a measured flow rate of the sample gas, a pressure measuring section that measures a primary side pressure in the flow channel, and a flow rate correcting section that corrects the measured flow rate obtained by the flow rate calculating section by the use of the primary side pressure obtained by the pressure measuring section and a gas coefficient determined by the sample gas, wherein the flow rate correcting section calculates a corrected flow rate Q offset based on a following expression: Q offset = Q raw × [ 1 - { ( a × Q raw + b ) × P i ⁢ ⁢ n - P base P i ⁢ ⁢ n ⁡ ( 0 ) - P base } ] [ Expression ⁢ ⁢ 8 ] where P in , is the primary side pressure, P base is a previously set reference pressure, each of constant a and constant b is a value determined by a gas physicality value of the sample gas and the primary side pressure, and the P in(0) is a primary side pressure at a time when the constant a and the constant b are obtained.