Abstract: A flow meter for measuring the flow of fluid through a pipe. The flow meter has an elongate member attached to an interior surface of the pipe. The elongate member has a leading end, a trailing end, a longitudinal axis, a first side, and a second side. The first side extends from the leading end to the trailing end and defines a cylindrical cross-sectional shape with a radius of curvature corresponding to the radius of curvature of the pipe and extending along an arc of less than 180 degrees. The second side extends from the leading end to the trailing end and is exposed to the interior of the pipe. The second side forms a constriction in a cross-sectional area of the pipe. Pressure sensors determine a pressure differential caused by the elongate member which is used to determine the volume of fluid flowing through the pipe.