The segmental wedge flow meter element has a V-shaped restriction cast or welded into a flanged meter body that creates a differential pressure.
Segmental Wedge Flow Meter
The functional principle of this measuring instrument is based upon the Bernoulli principle (continuity and energy balance equations). Using an wedge, a differential pressure is generated which can be equated with the mass or volume flow rate. The flow range is determined through the H/D ratio.
The restriction is characterized by the h/D ratio, corresponding to the β ratio of an orifice plate, where (h) is the height of the opening below the restriction (the only critical dimension) and (D) is the inside diameter of the pipe.
It can be used for a variety of corrosive, erosive, and highly viscous fluids and slurries. The discharge coefficient (Cd) is a stable for Reynolds numbers of less than 500 – allowing it to be used down to laminar flow regimes.
The upstream and downstream pressure taps are usually in the form of remote diaphragm seals eliminating the need for lead lines.
Wedge Flow Meter
Image Courtesy : controlplusinc
The differential pressure transmitter will be installed on the tapping points as shown in above figure. The wedge creates a differential pressure as like orifice and this differential pressure is measured using the DP transmitter and measures the flow rate.
Image Courtesy : Wika