Pump Suction

Hello vishals

Take the argument to its logical conclusion:

1. If the inlet was totally blocked, there would be zero flow.
2. In between full blockage and no blockage, there would be degrees of flow, inversely proportionate to the blocked amount.
3. If the inlet was not blocked at all, there would be maximum flow.

The reason for having a pump, and for that pump to be useful, is to be in action, pumping.

So, by the very nature of a pump, it is more efficient, and useful, to have no restriction on the suction side.

In saying that, often there is a strainer or filter on the suction side, to keep out sand/river stones and the like, or in an oil pump, there may be a filter to keep metal and carbon particles out of the finely machined gears.

In the case of strainer or filter, the pump and driving motor are made large enough to allow for the (generally small) frictional losses in the strainer or filter.

Trust you feel assisted.

Kind Regards....

Restrictions on the inlet side of the pump are the precursor to a condition where the action of the pump pulls the pressure at the inlet connection down to the boiling pressure of the liquid at its current temperature. At that point a phenomenon called cavitation occurs, which manifests itself as the impeller causing the collapse of tiny bubbles of vapour that has boiled off the liquid at the restriction. Cavitation can damage an impeller in short order, depending on the nature of the fluid, and usually leads to an early grave for the pump if not attended to by removing the restriction.

Cavitation can normally be heard, as the collapse of all that vapour is accompanied by the emission of a lot of sound; the pump will let one know when it's in distress.

As an experiment, try coupling a small Kamikaze centrifugal pump (typically 1/2in inlet or 0.5hp?) into a pipe system, pump some water around, and slowly close the pump inlet valve. Once the pump starts making a rattle, that's cavitation happening, which is the phenomenon best avoided in all pumping systems.

You can only 'suck' to 1bar...but you can pump to many bar...Thus restrictions should be on the outlet rather than the inlet.

Generally the inlet pipe should be as short as possible.

Del

Hi Vishal,

Always suction side should be free from restriction because oil is suppliying to pump (gear body) from suction side to develops the flow at pressure side through the meshing of drive and driven shafts ( Gear pump). If restriction happens in suction side you will not get the required flow and cavitation will happen due to that pump will get damage.

If your not satisfied with this please let me know we will try to answer you again.

Thanks

Janardhan Hunusnale

Pune.INDIA.