DP flow meter calculation

A cooling water system is operating at steady state condition. FT Shows 600 con with 50 psid across flow element. If flow increases to 900gpm what will be dp? Plz explain
Are you sure of your engineering units? a rather substantial 50 PSID drop across a flow element?

An increase in flow of 150% (900gpm/600gpm = 1.5 = 150%) will produce a corresponding increase in DP of 225%, an increase from 50PSID to 112.5 PSID.

sq rt of 225% DP (sq rt of 2.25 normalized) = 150% flow or 1.50 normalized
your pressure units are most likely "inches water column", as few flow meters are design to tolerate 50/150 psi pressure differentials.