Because the Model 110 typically controls the differential pressure, that particular parameter of the sizing equation is already defined. All that remains is to ensure the valve is large enough to handle the required flow within proper velocity limits.

    where:  Cv = valve coefficient
     where:  Q = Maximum flow rate, gpm
     where:  sg = Liquid specific gravity (water = 1.0)
     where:  dp = Differential pressure, psig

From the chart below, pick the smallest valve that has a Cv at least equal to the value calculated and where the velocity does not exceed 25 ft/sec.