THERMAL TYPE MASS FLOW METER, AND THERMAL TYPE MASS FLOW CONTROL DEVICE

The present invention provides a thermal type mass flow meter and a thermal type mass flow control device which can lower a measurement error caused by an influence of a thermal siphon phenomenon so as to intend to improve a flow rate measurement precision while it is possible to construct a whole compactly and inexpensively with a simple structure, without using any flow path converting block. The present invention has a CPU for correction computing process which works to cancel a measurement error caused by an influence of a thermal siphon phenomenon by calculating a correction value based on a measurement value at a time of depressurizing a fluid flow path in a block and a flow rate measuring conduit to an atmospheric pressure or less, a difference between the measurement value and a measurement value at a time of charging an actual fluid into the flow rate measuring conduit, a kind of the actual fluid, a pressure at a time of charging the actual fluid, and a flow ratio of the fluid flowing in the fluid flow path and the flow rate measuring conduit, storing the correction value, and correcting an actual measured output value by the correction value.