a question regarding HI Pump Intake Design requirement

[QQstuff]

I have a question regarding a requirement specified in Centrifugal/Vertical Pump Intake Design Centrifugal/Vertical Pump Intake Design 9.8-1998. In example 2 on Page 12, the min distance between the vortex suppressor and top of the horizontal pipe is 3D. In my application, the vertical pipe D = 36”, which could be 26” but it is sized to 36” due to the size of the diffuser bowl is 36”, which results in the velocity in the donut area of the 36” vertical pipe is 1.63 fps. If I comply with HI’s requirement of 3D, I cannot meet the NPSHr. I guess the 3D requirement is mainly to minimize the turbulence caused by the entrance velocity in the vertical pipe. Since the velocity is 1.63 fps, and the Max TDH in the system is 78 ft @ 4167 gpm, if it is possible for me not to comply with 3D requirement in order to meet NPSHr?

 

[Artisi]

I don't have access to a copy of the HI's data so your posting is not clear. Can you be a little more specific with the description of your installation.

Naresuan University
Phitsanulok
Thailand