KSB new waste water impeller combines efficiency and reliability

In an expansion of its range of pumps suitable for handling untreated waste water, the KSB group has developed a new radial multi-vane, open design impeller. The D-max impeller is for use in the Sewatec and Amarex KRT pump type series. These pumps handle fluids containing solid substances, long fibres, coarse solids as well as entrapped gas or air.

The D-max impeller is suited to handling untreated waste water, combined sewage, recirculated and heating sludge as well as activated, raw and digested sludge with a solids content of up to 8%. This impeller type is also suitable for transporting fluids with a high viscosity.

The new impeller’s efficiency is in the region of 84% and can be compared with the performance of closed multi-channel impellers. The impeller’s free passage of at least 76mm meets the requirements of many wastewater plant operators. KSB hydraulic experts employed computational fluid dynamics (CFD) to obtain knowledge about the complex flow processes inside the pumps using computer-aided simulations. In addition to the computer-aided development of impellers, KSB also conducted wastewater tests in the laboratory as well as field tests around the world. The results of the test were then incorporated in the impeller’s development programme.

All customers receive an impeller trimmed to match the specified operating point, which is also a common practice for multi-channel impellers. They are suitable for both 50Hz and 60Hz electric motors. The maximum head is approximately 90m and the maximum flow rate is approximately 2,800m3/hr. Depending on the composition of the wastewater, an operator can choose between the materials EN-GJS-400-15 and 1.4517 as well as EN-GJN-HB555.

The new D-max impeller serves to handle fluids containing solid substances and long fibres, coarse solids as well as entrapped gas or air (Image: KSB)