Product category:
Waste-water handling, monitors + treatment
News Release from: Hidrostal | Subject: Hidrostal immersible pumps
Edited by the Processingtalk Editorial
Team on 31 March 2006
Sump cleaning system to avoid blockages
A Thames Water contract to supply dry weather flow sewage pumps has been awarded to Hidrostal: the two immersible pumps to be supplied will incorporate the Hidrostal pre-rotation sump cleaning system
A major flood alleviation scheme is currently being undertaken by Thames Water in the Thames Ditton and Claygates areas of Elmbridge Flooding of raw sewage had become an increasing problem in the area because of pump failures
This article was originally published on Processingtalk on 24 Aug 2004 at 8.00am (UK)
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Blocking of the pump impeller had resulted in a surcharge of the sewerage system causing flooding of domestic properties.
To solve the problem and to meet future pumping requirements up to the year 2016 the pumping station and pipework is to be upgraded.
The contract to supply the replacement dry weather flow sewage pumps has been awarded to Hidrostal, a Thames Water Framework supplier.
The two Hidrostal immersible pumps to be supplied will incorporate the Hidrostal pre-rotation sump cleaning system.
This will prevent the build up of solid material floating on the surface in the pumping chamber that can often form a floating raft and cause the pumps to block.
The pumps will operate at 990 rpm and each pump will give approximately 480 l/sec.
The pumps have screw centrifugal impellers offering high pump efficiency and due to the large free passage have a very low risk of blocking.
The Hidrostal pre-rotation flow matching/sump cleaning system will come into operation at low sump levels, typically occurring at night.
At this point two things will happen.
Firstly, all the flow into the pump will go over a broad crested weir, this induces the top water together with any floating debris into the pump cell which is then removed by the pump.
Secondly, and at the same time, swirl starts in the pre-rotation basin.
This swirl causes the output of the pump to reduce.
The benefit of the reduction in output is that it will keep the pump in its skimming solids removal phase longer, and closely match the lower night time inflow.
As the pump approaches its maximum pre-rotation, the flow into the pump is through the side channel, which enables the pump to take the well down to very low levels and so remove heavier solids such as settled grit.
Commenting on the contract Derek Jackson, Hidrostal Managing Director said 'By installing the Hidrostal solution not only will the sewage flooding problems caused by blockages be solved but also the costs for unscheduled maintenance arising from pumps blocking and the need for maintenance effort to remove floating and settled solids from the sump, will be eliminated!'.
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