Abstract: A flowmeter has a variable area, vertically-oriented duct through which flows fluid whose flow rate is to be determined. A float in the duct assumes a position in the duct that depends on the flow rate of fluid in the duct. A window is located at an end of the duct in alignment with a longitudinal axis of the duct. A transducer unit projects a signal beam comprising either light in the ultraviolet, visible, or infrared spectrum, or ultrasound energy. The signal beam propagates in a beam through the window and along the axis toward the float. The transducer includes a sensor that detects the signal energy returned by the float by reflection or some other mechanism to the transducer unit. The intensity or delay time in the returned signal energy indicates the position of the float in the duct, from which the fluid flow rate may be determined.

Abstract: A flowmeter has a variable area, vertically-oriented duct through which flows fluid whose flow rate is to be determined. A float in the duct assumes a position in the duct that depends on the flow rate of fluid in the duct. A window is located at an end of the duct in alignment with a longitudinal axis of the duct. A transducer unit projects a light beam through the window and along the axis toward the float. The transducer includes a light sensor that detects light returned by the float by reflection or some other mechanism to the transducer unit. The intensity or other characteristic of the returned light indicates the position of the float in the duct, from which the fluid flow rate may be determined.

Abstract: A flowmeter has a variable area, vertically-oriented duct through which flows fluid whose flow rate is to be determined. A float in the duct assumes a position in the duct that depends on the flow rate of fluid in the duct. A window is located at an end of the duct in alignment with a longitudinal axis of the duct. A transducer unit projects a light beam through the window and along the axis toward the float. The transducer includes a light sensor that detects light returned by the float by reflection or some other mechanism to the transducer unit. The intensity or other characteristic of the returned light indicates the position of the float in the duct, from which the fluid flow rate may be determined.