How to get from pump flow rate to pressure change

[zzinfinity]

Hi,
Essentially what I need is a pump that will pump 40 gallons of water per hour to a height of 8 feet. Ignoring pressure losses in the lines (for now) I used the bernouli equation to determine that I need a pressure change of 3.44 psi in my pump. I found these pumps that look suitable but all list a max head far lower than the 8 feet I need. http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=21414

I was thinking maybe just use one with a higher volume flow to compensate for the head loss. Maybe the 100 gph one? Is there a way to determine exactly what I need? Thanks!

 

[SteamKing]

If the pump cannot deliver a head greater than 8', increasing the flow will not compensate. Find a pump which can deliver at least 8' of head, or re-design the piping system to reduce the head loss.

 

[zzinfinity]

Fascinating. Fluid mechanics has always baffled me. Thanks!

 

[huntoon]

http://www.drsfostersmith.com/pic/article.cfm?acatid=285&aid=282

here is their product comparison including head values.

 

[zzinfinity]

Out of curiosity, is there a fundamental reason why a pump that can pump 200 gph to a height of 5 feet, can't also pump 100 gph to a height of 10 feet?