Patent ID: 6012339
Filing Date: 2000-01-11
Classification: G01F

Abstract:
A flow meter for measuring rate of flow of a fluid, comprising:(a) a single unit housing having a first chamber and a separate second chamber with a dividing wall separating the chambers, the first chamber having an inlet and an outlet for fluid flow through a passageway extending therethrough;(b) a fluid flow sensing member mounted within the first chamber and at least partially disposed within the fluid flow passageway, comprising a rotor rotatably mounted on a shaft having an axis that is tangential to the fluid flow; the rotor having at least two blades each having a tip portion, and a signalling element in the form of a magnetic member mounted within the rotor; the rotor being rotatable by contact of fluid flowing through the passageway;c) a magnetically-operated sensor mounted within the second chamber in proximity to the signalling element in the rotor such that for each rotation of the rotor, the signalling element causes the sensor to produce a first signal; and(d) a signal-conditioning circuit housed within the second chamber and including linear circuitry operable to receive the first signal from the sensor and convert the first signal into a second 4-20 mA output signal that indicates the flow rate of the fluid through the passageway such that an amplitude of about 4 mA is equivalent to an about zero flow value and an amplitude of about 20 mA is equivalent to a predetermined maximum flow value;the rotor being configured and dimensioned to continuously rotate during fluid flow through the flow meter and provide a linear relationship between the rate of fluid flow through the meter and the output signal, the rotor having a depth of about 11-12 mm, and each blade having a width of about 5-7 mm and a length of about 8-10 mm, with the length being about 11/2 times the width; andthe circuitry being operable to allow direct connection of the flow meter to an analog processor without connection to an external conditioning circuit.