Ewan Fraser, engineering manager, says it was the best solution – noting that lime is abrasive and viscous, causing problems for progressing

cavity and diaphragm pumps.
His chosen pump is abrasion-resistant and ensures smooth passage of the liquid. It also prevents settling, due to its peristaltic action. Further,

the lime can be mixed on site, as solids in the liquid stream present no problem. And, because of its linear flow characteristic, it is also ideal

for feedback speed control, which minimises chemical usage.
But there are a few other aspects worth attention. First, the Dura has a novel drive that Verder claims provides a 70% smaller footprint than

similar pumps. Secondly, it offers very good reliability, due to its rigid drive connection. Thirdly, the rotor is mounted directly over its

bearings, so there is no overhung load. Also, it doesn’t require any shims, so installation is simple and power consumption low.
And two more points. First, because this pump has a low operating temperature, hose life is claimed to be 40% better – helped by its reinforced

layer construction. Secondly, the bearing is sealed for life and positioned to centrally absorb forces – further enhancing durability of pump and

drive.