It's been a looooooong time since I delved into fluid properties. I'm trying to predict flow based on a known static head. I have a water column which will result in 6 psig of static head. The height of the water column will not change during the flow. I know the downstream piping will flow at 51gpm with a 125 psig source throttled to 5 psig and 40 gpm when throttled to 3 psig. I don't need very many significant digits! Thanx for any help.