Horizontal Split Case - Straight Pipe Requirement at Suction

[IBechir]

Greetings

This is regarding clear water application for building chilled water pumping station.

I understand that an end-suction pump requires a straight pipe at its suction. What about a horizontal split case? Some volutes include an elbow/turn on the suction and discharge sides, so pump suction and discharge connections are pointing vertically. Other volutes don't include an elbow/turn and have the suction and discharge connections horizontally, in the same line.

Its better to always consult the manufacturer about pump requirements but is it necessary in this case? Is there a rule for all horizontal split case suction pipe connections? If its not needed for one pump of the same type why would it be needed for another pump from a different manufacturer? I have not seen a suction diffuser used for horizontal split case.

Much obliged for any information

 

[HPost]

Centrifugal pumps work better with minimal disruption to the inlet flow stream. where possible, it is always better to have an axial pump inlet. Adding any device to change the flow direction will affect the pump performance. NPSHa and energy efficiencies suffer.

Split case pumps cannot have axial inlets, so the flow is brought in radially and channelled towards the impeller inlet eye through the casting.

Do what you can to facilitate an axial inlet, if you cannot do so, then use a radial inlet. However, make allowances for the losses.

It is always a good idea to consult the manufacturer as they will be able to give you a heads up on the anticipated pump performance with both radial and axial inlets. If you are using a split casing pump, you can't change it anyway...so just connect to the inlet flange.

Cheers

HPost CEng MIMechE