FORM -2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL
Specification
(See section 10 and rule 13)
SUMP PUMPS
KIRLOSKAR BROTHERS LIMITED
an Indian Company
of Udyog Bhavan, Tilak Road, Pune 411 002,
Maharashtra, India,
THE FOLLOWING SPECIFICATION DESCRIBES THE INVENTION.

This invention relates to sump pumps.
In addition this invention relates to pump intakes.
Sumps are used as intake to pumps. The basic purpose of a sump is to supply water with uniform velocity at the entry of impeller. As the pump capacity increases, the sump dimensions also increase proportionately.
An ideal sump must provide uniform, smooth and swirl free flow to pumps. The most critical part of a system involving pumps is the suction approach. A centrifugal pump that lacks proper pressure or flow pattern at its inlet will not respond properly or perform to its maximum capability. Uniformity of flow and flow control to the point of pumped fluid contact with the impeller inlet vanes are the most important.
A minimum submergence level is needed for the inlet port i.e. the draft tube of the pump below the level of the water or fluid in the pump.
When the submergence level, is less than this surface vortices or cones, are created, produced by the localized eddies on the surface of the water. These surface vortices may get converted to strong a submerged vortex leading to air entrainment at the inlet port of the pump. The vortices that form near the pump bell may be classified as free surface vortices (which could transform into air-entainment) and wall attached vortices (submerged vortices). If these vortices in the form of disturbance continue, the flow of water will carry the underwater part of the vortex down toward the pump suction bell and ultimately into the pump.
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Poor pump intake can results in an approach flow with a high swirl levels, while an inappropriate geometrical layout near the pump bell may lead to strong boundary attached sub surface or submerged vortices. These vortices ultimately introduce air into the impeller and affect the mechanical radial balance of the impeller by interrupting the normal solid- liquid flow pattern. This type of disturbance produces hydraulic pulsations in the pump flow and mechanical overloading of bearings and impeller guides.
Thus problems associated with this air entrainment lead to vibrations, impeller damage / wear due to cavitation, deteriorated performance and a significant increase in operational and maintenance costs.
An object of the invention is to provide smooth flow over the entire flow range of pumps and in all the combinations of pumps.
The air entrainment in sumps is a commonly observed phenomenon at low water level. Centrifugal pumps in intake pumps therefore must be submerged deeply enough to have sufficient prevention of vortexing/formation of air entrainment all the time of pump's operation.
Any reduction in the required submergence provides a lot of financial gain. There is always a search for a device / method, with which requirement of submergence can be reduced.
This invention in one aspect of it teaches that to attend to this air entrainment when there is indication of the entry of air bubbles through the draft tube of pumps, is to minimise the formation of air bubbles at the
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entrance of draft tube, by extending the draft tube inside the pump chamber and hence the back wall is also shifted up to the end of extended draft tube.
The provision of extension in the draft tube eliminates the formation of air entrainment.
The device to this invention helps to work the pumps without formation of air entrainment with lower submergence than normally required and therefore permits operation of pumps in relatively shallow water levels less than the minimum submergence level.
In accordance with another aspect of the invention, there is provided as canopy over the intake tube leading to pump, thereby effectively blocking the pathway of the air bubbles from the surface and therefore blocking air entrainment.
Dated this 24th November2006.
Mohan Dewan
of R. K. Dewan & Co
Applicants' Patent Attorneys
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