I have a 3" line with 125 PSIG well water being used as makeup water to a cooling tower to help prevent foaming. I would like a restricting orifice to limit that flow to approximately 80 GPM.

 

Hi Dan,

Use this formula to get the plate orifice internal diameter D1
http://www.pipeflowcalculations.com/orifice/theory.htm

For fluid application (water, for example) the e - expansion coefficient will be 1, but you have to select maximum allowable differential pressure deltaP or pressure loss.

Or you can download this sizing tool but only with trial version.