Center Axis of Elbows & Vertical Inline Pumps 1

[Oremus]

Can elbows be located in any orientation and any location when it comes to vertical inline pumps? All the requirements in '20 for restrictions on the orientations of elbows seem to only be applicable to horizontal splitcase.

Thx,

 

[TravisMack]

My understanding is that the orientation limits are only for Horizontal Split Case as well.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692

 

[Oremus]

Thanks Travis, I always just envisioned a vertical inline pump as being identical to a HSC but turned vertically. I guess I was wrong.

 

[skdesigner]

The key difference is that horizontal split case pumps utilize "double suction" impellers, where water enters the impeller from both sides of the eye. Vertical inline pumps use single-suction impellers, where water enters from only one side of the eye. For a horizontal split-case pump, water flows from the suction piping into the pump casing, splits evenly around the impeller and then flows into both sides.

When water flows through an elbow, the water travelling on the "outside" of the elbow has a longer distance to cover than water on the "inside". When the elbow is laid on the horizontal plane in close proximity to the pump suction flange, this creates an imbalance that is carried into the pump since the water is no longer flowing evenly into both sides of the impeller eye. The result is increased strain on the driveshaft and bearings, as well as the potential for cavitation.

To confuse you further, vertical split case fire pumps do actually exist.

R M Arsenault Engineering Inc.

http://www.rmae.ca

 

[TravisMack]

Thanks SKD...that is actually an explanation that I can understand and makes sense.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com

"Follow" us at

https://www.facebook.com/pages/MFP-Design-LLC/92218417692

 

[skdesigner]

Glad I could help Travis - love the facebook page!

R M Arsenault Engineering Inc.

http://www.rmae.ca