Importance

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Abstract

A flow meter has a body, an inlet operatively connected to a source of gas, and an outlet. A valve for opening and closing the outlet is provided which includes a valve seat, a valve shaft movable axially relative to the valve seat and a valve member on the valve shaft. The valve member movable by axial translation of the valve shaft between a first position in which the valve member engages the valve seat to close the outlet and a second position in which the valve member is spaced from the valve seat to allow gas to pass through said outlet. The flow meter further includes a sensor which senses the position of said valve member relative to said valve seat and generates a signal indicative of said position. In one embodiment, the sensor comprises an infrared light emitter and an infrared photo-detector positioned on opposite sides of the valve member, which is preferably conical. Depending on the axial position of the valve member, the amount of light which reaches the photodetector changes. In another embodiment, the valve shaft is operable connected to a potentiometer which is responsive to the rotational position of the valve shaft, and hence the axial position of the valve member. In a third embodiment, a magnet is placed about the valve shaft, and a magnetic field detector is placed within the magnets magnetic field. The sensor is responsive to the position of the magnet and hence the position of the valve member.

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First Claim