Abstract: A flow meter having a float slideably mounted along a float rod centrally located within a flow meter body, the float assuming a height along the flow meter float rod representative of fluid pressure. The float preferably has a cylindrical-shaped through-bore. The float rod preferably has a polygonal-shaped perimeter over substantially its entire length permitting fluid flow between the float rod outer diameter (OD) and the float inner diameter (ID) to dislodge any particulate, thereby serving a self-cleaning function. The float rod is preferably hollow and closed at its upper end and having flow inlet and flow outlet openings near its lower end communicating with a flow chamber which conveniently provides the inlet and outlet flows at the lower end of the flow meter.

Abstract: A flow meter having a float slideably mounted along a float rod centrally located within a flow meter body, the float assuming a height along the flow meter float rod representative of fluid pressure. The float preferably has a cylindrical-shaped through-bore. The float rod preferably has a polygonal-shaped perimeter over substantially its entire length permitting fluid flow between the float rod outer diameter (OD) and the float inner diameter (ID) to dislodge any particulate, thereby serving a self-cleaning function. The float rod is preferably hollow and closed at its upper end and having flow inlet and flow outlet openings near its lower end communicating with a flow chamber which conveniently provides the inlet and outlet flows at the lower end of the flow meter.

Abstract: A device for converting a position of a float member in a rotameter in to an electrical output. Light from a light source is collimated into parallel light rays, at either or both opposing sides of a rotameter tube to greatly enhance accuracy of readings. The lightrays passing through the tube are detected by a linear optical array. A range of movement capable of being read by the linear optical array is extended by use of either a fiber optical array or a movable illumination device and linear optic array. The collimator(s) may be a linear array of one or two rows of cylindrical lenses sandwiched between a pair of plates. The linear optic array maybe arranged on opposite sides of the rotameter tube or may be on the same side there of. A light guide is used in the latter arrangement to guide light from the light source to a side of the rotameter tube opposite the linear optic array which may be a charge-coupled device(CCD).

Abstract: A movable piston is arranged within an open-ended cylinder, the piston having a peripheral groove for receiving liquid mercury to create a sliding gas-tight seal between the piston and the cylinder. The cylinder wall is provided with a plurality of openings, arranged to prevent mercury from escaping through said openings while permitting gas introduced into the interior of the cylinder to escape therefrom. When the piston reaches an equilibrium condition, the height of the piston represents the gas flow rate, which is determined by the flow rates through the total number of openings beneath the sliding seal. As an alternative embodiment, the flow rate is controlled by a downwardly moving piston. As another alternative embodiment, the piston is free to move up or down to compensate for fluctuations in pressure and/or flow rate within the cylinder.