Verderflex Supplies Solution for Yorkshire Water's Lime Dosing Problem

Yorkshire Water is one of the largest water treatment companies in the UK, treating water and wastewater for millions of homes. Yorkshire water approached Verder to provide a pumping solution for them as they were having problems with their lime dosing pumps at their Ruswarp water treatment plant near Whitby.

Durable Pump

Hydrated lime and lime milk is added to the water supply and has several beneficial effects. The lime removes the hardness from drinking water, balances out the pH level of the water aiding the purification process and also draws out heavy metals such as insoluable hydroxides. Hydrated lime is completely safe to use and conforms to BS EN 12518: Class 1 Type A. Yorkshire water needed a durable pump that could accurately dose abrasive material and would be simple to maintain.

Verder have a great deal of experience providing pumps for dosing abrasive materials and have supplied similar water industry installations.

The original pumps used for dosing Kalic Liquid Lime at Ruswarp were solenoid driven diaphragm pumps. When used at low flow rates these pumps could easily become clogged with the viscous material. This would cause long periods of downtime for maintenance and repairs. Verder recommended replacing these pumps with peristaltic pumps.

Self Contained Pumps

These self contained pumps use a natural pumping principal, similar to how a throat works, to provide consistent performance. A rotating shoe compresses along the length of the hose forcing the material forward. When the compression is released the vacuum created causes more fluid to be drawn along the hose. As the material only ever comes into contact with the hose, none of the moving parts of the pump can be effected by the pumped material. To increase longevity the hose is incredibly durable and comprises of an inner layer, up to 6 layers of reinforcement and a tough outer layer. Measuring and dosing can be adjusted by changing the diameter of the hose and the speed of the rotating shoe. Maintenance is simple as only the hose needs to be replaced. These pumps are also able to self prime up to a depth of 9.5 metres and are specially designed to prevent clogging.

Water Treatment Pumps

Five Verderlfex peristaltic pumps were installed at the Ruswarp plant under the instruction of consultant engineers Earth Tech/Morrision. The installation includes two VF15's for pre Kalic lime liquid pumping, two VF10's for post Kalic lime liquid pumping and a VF25 re-circulates the solution to the storage tanks. The new water treatment pumps are still controlled by the original site PLC and the existing inverters allow variable speed and flow control. The separate controls for speed and stroke needed for the old pumps were also replaced. The installation was carried out without interrupting the water supply and since their installation there has been a marked reduction in downtime for maintenance work.