The target meter combines in a single unit both a primary element and a force balance flow rate transmitter. A circular disc (or target) supported concentrically in the pipe carrying the flowing fluid results in an annular orifice configuration. Pressure difference developed by the fluid flow through this annular orifice produces a force on target proportional to the square of the flow rate. This force is carried out of the pipe through a rod passing through a diaphragm seal, and is measured by a pneumatic or electronic force balance system identical with the mechanism of the force balance D.P. cell.
The advantages of the target meter lies primarily in its single unit construction the primary device and responsive mechanism in a single structure. This eliminates the diff. pressure fluid connections in most heads meters. This is particularly used for sticky and dirty material which may plug up differential connections and for liquids which require elevated temperatures to avoid solidification, this elimination of liquid connection is useful.