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Gorman-Rupp self priming pumps and a self cleaning wet-well

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article image Gorman-Rupp self priming pumps and a self cleaning wet-well

Is the cleaning of a wet-well just a costly and troublesome fact of life? Or is there truly an effective, cost efficient alternative?

The typical wet-well consists of a pair of submersible pumps sitting at the bottom of a wet-well (or pit) that could be between 1.5m and 3.0m in diameter. The pumps are fitted to guide rails, which guide the pumps onto discharge elbows located at the base of the well.

The pumps cycle alternatively during inflow periods (generally heaviest around meal times), and pump between the “on” and “off” levels in the well. These levels are generally determined by the level of the gravity influent line (invert level) and the level equivalent to the top of the pumps.

The best solution is prevention (that works), rather than a cure (cleaning after fat build up). Gorman-Rupp self priming pumps, when used for the main pumps at the station, can be “set up” to provide a “self-cleaning” function: 

  • without adding one extra piece of mechanical equipment to the station 
  • without adding a single electrical component to the control system 
  • and without having to enter the wet-well or even open the wet-well lids.
The answer lies in taking advantage of the air handling capabilities of the Gorman-Rupp self-priming centrifugal pumps.

Provided suction conditions are right (and Gorman-Rupp Super-T series and Ultra-V series pumps are designed to be able to prime to 7.5 metres), suction lines can be set very close to the bottom of the well, and pumps run until they lose prime (are basically ”sucking air”).

This means that virtually all of the contents of the wet well are removed (including the oil and fat) with each and every pump cycle, not giving greases a chance to build up at all. To achieve this result, pumps can be retrofitted to existing wet wells with conical shaped bases, or older style rectangular wet wells, as well as purpose-built new ones.

In all these cases, because self-primers only need a small amount of space for the suction lines to fit into, they can be positioned at the deepest and narrowest part of the well to ensure that the surface area of un-pumped fluid after the pumping cycle is much smaller than the maximum diameter of the well. In some cases, the surface area remaining can be as little as one tenth the surface area of the main chamber of the wet well, so at the very least, in this instance, fats will take up to ten times as long to build up.

There are numerous other benefits to using self-priming pumps in wastewater applications which include: 

  • Lower maintenance costs 
  • Longer service life 
  • Greatly improved O. H. & S. conditions 
  • Safer operation 
  • Virtual elimination of Confined Spaces issues

Gorman-Rupp self priming pumps are available from Hydro Innovations .

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