Suitable for short straight lengths and low permanent pressure drop
The venturi tube has a convergent inlet, a throat and a divergent outlet. It is a differential pressure flow meter well known to create a low permanent pressure drop; thus, it is suitable for measuring, for example, a low pressure flow rate. More over, it requires short upstream and downstream straight lengths.
There are different types of venturi tubes : the machined venturi made from a solid round for small size parts, the rolled welded venturi made from sheet metal for larger pieces up to 1200 mm diameter and the venturi "as cast" allowing a better accuracy up to 800 mm diameter.