The driving head protects the internal thread and the top of the solid copper earth rod from damage when being driven into the ground. These Wallis re-usable threaded driving heads are suitable for driving earth rods by hand or with a power hammer. The driving head screws into the threaded coupling to allow deep driving of the earth rods.
A common misconception by designers of stormwater treatment devices is to use the physical drop between inlet and outlet pipes, Elevation Head (∆z), as the Total driving head instead of the hydraulic drop between upstream and downstream water surface elevations, Driving Head(∆h).
This relationship between Elevation Head (∆z) and Driving Head (∆h) can be further explained in Figure 1 below. The physical drop (Δz) between inlet and outlet pipe inverts is shown as 240mm, whereas the driving head (Δh) at maximum treatment peak flow is shown as 750mm between the outlet invert and the internal bypass weir invert. This configuration will result in a minimum 510mm (Δh-Δz) surcharging headwater condition upstream of the inlet pipe.