For demonstrating Bernoulliâs principle that any restriction in ï¬uid ï¬ow results in increased speed and decreased pressure. Comprised of borosilicate glass tube 18cm (7in) long and 18mm (3/4in) in diameter with a constriction in the centre and three vertical openings in different sections. Includes three glass manometer tubes and rubber connecting tubes for measuring pressure at three locations. Ends are ï¬ared. 3450-00 Note: Venturi tubes of other dimensions and speciï¬c wall thickness can be supplied.