FLOW RATE MEASURING DEVICE

PURPOSE:To make the title device highly accurate in measuring a flow rate in a full flow zone while allowing the use of general-purpose pressure sensors, which are easily obtainable, by a method wherein said device is provided with an arithmetic and control unit which corrects a value actually measured by each sensor on the basis of an error approximate value, computes the calculated value of a flow rate from the value obtained by this correction and outputs a signal of the calculated value. CONSTITUTION:In a case where an approximate value for each of sensors 3, 6, 7, which is calculated by applying an error approximation formula, becomes larger than a predetermined value, an arithmetic and control unit 8 produces an alarm signal or corrects the value actually measured by each of said sensors on the basis of the approximate value, and the calculated value of a flow rate is computed every moment from the value obtained by this correction, whereupon a signal of the calculated value is outputted. In addition, the arithmetic and control unit 8 has a control function for controlling a flow rate, or for controlling a pressure difference or an opening degree of a variable throttle means 5 to a predetermined value, and sends an opening degree control signal to a variable throttle driving means 4 to regulate the opening degree of the variable throttle means 5.