I took you through this exercise to show you how the formulas we use in these papers are derived. We will re-write the flow and orifice diameter formulas again and maybe this time they will be simple enough for anybody to use. If you are making calculations for a liquid other than water you will have to factor in the viscosity of that liquid compared to water. There is another formula we use for a less restrictive orifice. The piping material and allowable wall thickness tolerances.
Solids buildup inside the piping.
Calcium in water applications and coke in hot oil applications are typical. Higher temperature usually hastens the solids buildup. The Mc Nally Institute 1986 S. Belcher Rd.