Annular flow meters are **differential pressure flow meters**, annular meters are introduced to overcome the defects the problems in orifice flowmeters. Such flow meters are listed below:

## Annular Orifice:

Annular orifices were developed to overcome the problems of dirt built up in front of the orifice plate in liquid streams and liquid buildup in the moist gas stream. The total pressure tap and rearward facing taps produce a high differential pressure.

## Target flowmeter:

The target flowmeter has the feature of the annular meter without the disadvantages of freezing or plug lead lines. The primary element consists of sharp-leading-edge disk fastened to a bar. The differential pressure produced by the annular creates a disk drag force. This force is transmitted through secondary force measuring bar. And the flow rate is calculated as the square root of the output using **square root extractor**.

## “V” cone:

The V cone is differential pressure meter, the fluid accelerates through the annular cone. The differential pressure produced across the V cone is measured. The Dp created by a V-Cone flow meter will increase and decrease exponentially with the flow velocity. The square root of measured differential pressure is the flow measurement.

The V-Cone flow meter is similar to other differential pressure (Dp) meters in the equations of flow that it uses. V-Cone flow meter geometry, however, is quite different from traditional Dp meters. The V‑Cone constricts the flow by positioning a cone in the centre of the pipe.