U-bend before pump suction inlet.

[danialzulkifli]

Hi,

I went for a site visit to an existing plant, and saw that there is this U-bend piping before the suction of a centrifugal pump for a sump pit. My question is, is this bending required and what is it for? Thank you.

 

[moideen]

It looks like an installation mistake. Why create a pressure drop in the suction line and resulting cavitation?

 

[goutam_freelance]

It introduces pressure drop as already been said. Which increases possibility of cavitation.

It introduces flow disturbances at suction increasing the propensity for cavitation again.

It provides a place for air to accumulate and thus may result in vapor lock and reduction of flow.

 

[pierreick]

Hi,
weird design, troubles for sure.
Pierre

 

[Compositepro]

It makes the pumps self-priming to some extent, in that it keeps water from draining completely out of the pump casing. There is a tee on the pump discharge with a ball valve for adding priming water (or pulling vacùum).

 

[TenPenny]

It looks like an attempt to help create a pseudo self-priming pump. It might actually work if the pumps are occasionally shut down, but I surely wouldn't rely on it.

 

[bimr]

It appears to be installed that way for 2 reasons:

1. To allow the drop pipe to be removed.
2. The drop pipe is not aligned with the centerline of the drop pipe. The piping allows the installation without elbows in the horizontal pipe.

The arrangement probably would cause operational problems with a larger pump.