(Minor–loss can be minimized by slowly or gradually expanding the diverging section. That is why, the venturimeters are long, bulky, and expensive)
(without loss)
For Venturimeters,
or actual flowrate is calculated as, where is called the discharge coefficient and accounts for minor–loss or viscous–loss, because of non- uniform flow– patterns in the converging–diverging sections and at throat. The supplier of the instrument provides a plot to calculate :
(Neglecting minor-loss)
(without loss)
or actual flowrate is calculated as, 
where 
is called the discharge coefficient and accounts for minor–loss or viscous–loss, because of non- uniform flow– patterns in the converging–diverging sections and at throat. The supplier of the instrument provides a plot to calculate 
