Runner Areas

Of primary concern for an effective runner system is the Volume to Surface ratio.  Minimizing the surface area of the runner reduces the cycle time and pressure drop.

Equivalent Hydraulic Runner  Diameter calculations  can be  performed to compare various runner cross sectional shapes.  Hydraulic Diameter (Hd) is an index of the resistance of flow, The higher the Hd the lower the resistance to flow.

The formula :    4 A /P = Hd

               where:    A = cross sectional area
                                P = perimeter
                                Hd = Hydraulic Diameter