| | | It is very clearthat blockage is still a major problem when handling wastewater In total, it accounts for more than 50 % of the site visits to a typical wastewater pumping station. Blockage can be caused by eithersoft items; rag and otherfibrous materials or hard items where a solid item becomes jammed in the impeller To achieve effective wastewater handling it is necessary to focus on all components of the blockage mechanism, the Contrablock system has been proven in more than one million installations the world over The main features of the Contrablock system are: | | |
| | | LARGE FREE SOLIDS PASSAGE Installation of eguipment with high hydraulic efficiency is one of the results of the increased focus on energy. However it is very important to be aware that in many cases higher efficiency is achieved by increasing the number of impellervanes, resulting in reduced free solids passage and therefore increasing the risk of hard blockage. The ABS Contrablock system focuses on achieving the best efficiencywhile still maintaining large free solids passage. This is achieved by optimizing impeller profiles using CFD technology and notjust adding more vanes. The end result is good efficiency levels without increasing the risk of blockage. SEAL PROTECTION FROM SPINNING FIBRES Pump blockage is not the only damage rag can cause passing through a pump. In many cases mechanical seal failure has been caused by rag becoming wrapped around the back on the impeller The ABS Contrablock system makes use of either a castellation and spiral or back vanes working with a spiral and sine-wave shaped home cutter to avoid this problem. The end result is no rotating fiber orsand accumulation at the medium side of the mechanical seal, greatly increasing reliabilityand reducing the risk of soft blockage or seal damageon the rearside of the impeller ADJUSTABLE SPIRAL BOTTOM PLATE FOR EFFICIENT RAG HANDLING AND EFFICIENCY REGAIf Looking at the causes of soft blockage the typical reason is that the rag gets hung up before being passed through the impeller The Contrablock system makes use of an adjustable spiral bottom plate with a spiral grove radiating from the centre to the outside edge of the plate. Any rag that is caught under the impellerwill therefore be pushed out back into the main flow of liguid and through the impeller, greatly reducing the risk of soft blockage. To maintain this efficient rag handling and regain efficiency loss due to wear, the bottom plate can easily be adjusted from the outside of the pump without the need to return the pump to a workshop. | | |