Actually it did sink in after being drilled into me multiple times, but only while having it in the back of my mind while looking at axial and radial pump curves at the same time did it explain (or more likely "click") why axial pump curves tended to show less power required at greater flow...
I agree, this is more of a physics teacher question the get the answer I'm looking for in the way I was originally asking.
I did find that site illuminating, I found it after 1gibson mentioned axial pumps. It was a good idea to post it because it does help and made even more sense to see it...
I was quickly trying to say that comparing the pump curves of axial and radial pumps is what best helped me understand that it's just a difference in pump characteristics and tell people thanks. Yes, I forgot to mention increased flow due to reduction in head. In general I would say it is...
Learning about axial pumps using less power at higher flow rates did the most to help me understand that it is all just a difference in how radial pumps work. Thanks guys!
Thanks everyone, I am convinced! Is there a good site for calculating how much feet of head a 90º elbow in 1.25" PVC is equivalent to. At this point I'm going to upgrade my intake from 1.25" to 1.5" because I already cut it, but leave the rest of it alone.
cvg, mine is single-speed: voltage constant => motor stays same speed => pipe size increases reducing resistance => flow increases from less resistance => surprisingly more amps. That is what doesn't make sense to me, in every field less friction/resistance reduces power requirements not...
Let's say you have an impeller that is 4" diameter and the vanes start at 1" from center and extend to the very outer edge. What happens to the pump performance curve if you take .25" of the vane off the outside and put it on the inside, thus keeping the vane the same length? Will peak HP...
DubMac, I tried to think about what was going on at the flanges and thought my idea that the outer flanges had to do the majority of the work at higher flow rates would explain the higher power requirement. Apparently it makes no difference.
I have read the posts and appreciate them. They refer to system and pump performance curves. What is not explained is "why" more power is required at high flow rate. There has also been no analogy where resistance to work has been removed but removal of that resistances REQUIRED more power.
Wow, thanks for the detailed replies everyone! I am convinced if not from reasoning, then from sheer opposition to my opinion! I would like to know the true reason that explains why less resistance to work requires more power because it goes against pretty much everything I know... However...
In regards to pool pumps, I was told that if I increased the pipe size from 1.25" to 1.5", my 1hp pump would draw more power because of the increased rate of flow. They backed up that claim with "head curves" from pool pump manufactures showing an increase in HP required for low-head...