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| | Application: Sand Pumps for grid traps in STP's |
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| Vortex NiHard4 submersible pumps |
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Sand & Grid traps: the system
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Every sewage treatment plant, new or old, will have a sand and grid trap as part of the primary treatment stage. The most widely used design diverts the incoming flow over several grid channels in which the flow velocity is reduced, so that sand and other heavy abrasives will settle.
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Sloped walls guide the sand into a small gutter at the bottom in which sand pumps, suspended from a travelling bridge, are moved up and down.
Each grid channel has it's own small pump, irrespective of the size of the plant as they just lift the sand from the bottom into a side-channel alongside the main grid channel from where it is further moved by gravity.
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The RD 21 series wear resistant vortex pumps are specially developed for sewage treatment plants to remove sand and grid from the bottom of the grid channels. For over 25 years they prove their reliability and cost effectiveness in many plants worldwide.
All hydraulic components are from abrasion resistant NiHard4. This includes the impeller, pump casing and the special wear plate that protects the mechanical shaft seal and seal housing.
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NiHard4
NiHard 4 is a casted hi chrome nickel alloy that is naturally hard. With a Brinell hardness of over 500 it's harder than silica sand and yet strong enough to withstand shock impacts by rocks etc. as can be expected in pumps.
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5 Good reasons
for choosing Robot NiHard vortex pumps
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| Vortex pumps create that little extra turbulence just below the suction mouth needed to lift up the heaviest particles. | | | | | The NiHard4 material for the hydraulic parts proved to have a very good price / life rating. | | | | | Vortex pump show low to zero drops in performance over a long time without the need for impeller to liner re-adjustments. | | | | | Replacing the wear parts is very easy and fast. No specific skills are needed, again due to the lack of adjustments. | | | | | The vortex pumps are hardly affected by rags and other stuff that still floats in the grid channels. |
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The Robot BD series NiHard4 vortex pumps for dry installation are the equivalent of the submersible pumps. These pumps are used in the sand wash installations.
Where cast iron pumps show high wear rates the BD series NiHard4 pumps are a good alternative for circulating digester sludge.
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Products&Specifications
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