SAO nozzles consist of an inlet venturi nozzle followed by a cylindrical throat as well as an outlet cone with a full angle of 8 – 15°. If the throat diameter is equal to the outlet tube diameter, an outlet cone is not required. SAO nozzles are mostly turned and welded of aluminium or stainless steel.
The plus pressure measurement is taken in the atmosphere. The minus pressure tapping is carried out in the throat in the tube wall by one or several single bores. It is recommended to connect them by a ring line in case of larger diameters.