Non-obstructive thermodynamic flow meter

Abstract From the Canadian patent

A non-obstructive thermodynamic flow meter is disclosed which mounts substantially flush with the inside wall of a pipe and uses thermal techniques to measure the rate of flow of the fluid passing through the pipe. Two resistance temperature detectors are mounted flush with the inside wall of the pipe and are utilized as sensors. These two sensors are connected into a bridge circuit with a heater heating one of the two of them. The bridge circuit is balanced with no fluid flowing in the pipe. As fluid flow increases the heated sensor cools and changes resistance to unbalance the bridge circuit. The unbalance voltage across the bridge circuit is amplified and causes more power to be applied …