Orifice Diameter
The orifice equation was used to determine the necessary area of the orifice that gives the correct amount of head and matches with an existing drill bit size. The flow rate used in this equation was the total plant flow rate divided by the number of orifices. The minor loss coefficient for an orifice is assumed to be 0.63. The head loss term in the equation is total head available less the head loss in the manifold pipe less the velocity component of head loss through the pipe.
This area was then converted into a diameter and rounded to the next smallest drill bit size (0.7541cm or 19/64").