In comparison with orifice plates and flow nozzles, the venturi tube is expensive, because it is large and it has a complicated structure. However, it has many merits such as the extremely small pressure loss, less tendency of sludge and sediment deposition, high durability, and a short straight tube that is necessary. Venturi tube has the classical venturi tube and the venturi nozzle. Classical venturi tube with a machined convergent and with a rough-welded sheet-iron convergent are used commonly.
