Flow meters - Import export

Differential pressure flowmeter with upstream pressure tap located at a distance of D from the upstream face of the orifice plate and downstream pressure tap located at a distance of 0.5D from the upstream face of the orifice plate.

The sonic state of the nozzle means that the flow reaches the speed of sound when going through the throat. Under these conditions, the flow rate depends mainly on the upstream pressure and the fluid temperature. This makes it possible to deliver a stable and perfectly known flow, independent of the downstream pressure conditions of the nozzle. This nozzle is thus used to provide a standard flow value when it comes to calibrating another type of flow meter.