Flow meter for measuring the flow rate in a conduit

Abstract From the Canadian patent

The flowmeter includes a piston that is biased by a spring to a neutral position within an encircling collar, and the piston is movable relative to the collar by and in the direction of the fluid flow to be measured. Movement of the piston relative to the collar increases the fluid flow through one or more slots provided in one of such components. A Hall device senses movement of a magnet connected to the piston, and produces an output signal. A linear relationship between the output signal and the rate of flow of the fluid can be achieved by utilization of a magnetic member whose magnetic intensity or crosssectional shape varies along its length or by causing, the magnet to move along a …