Venturi tubes are welded structures of steel or stainless steel, mainly with round cross-section. They consist of an inlet cylinder, an inlet cone, followed by the cylindrical throat and the outlet cone. Classic venturi tubes are designed as different types according to the manufacturing method of their inner surfaces. A distinction is made between venturi tubes with treated inlet cone, inlet cylinder and throat, as well as a rough inlet cone welded of sheet steel.
Classic venturi tubes have very low remaining pressure drops according to the manufacturing of the inlet cone and the angle of the outlet cone due to good flow control. Plus and minus pressure tappings are carried out in the tube wall on the inlet and at the constricted area in the throat by one or several single bores. It is recommended to connect them by a ring line in case of larger diameters.