Morphling's has an article up!
 

Morphling's been busy!

Check it out!

A thing in this article about graph with 1 and 2 pumps shoked me a little...

I have do the pic below to explain :

http://membres.lycos.fr/roscool/forum/pic2L.gif

Morphling has put a pressure drop equal for 1 and 2 pumps but more flow is more pressure drop, it isn't linear at all ! Pressure drop for a bloc is "similar" to a parabolic curve like in my mod pic.

There aren't ONE green line but TWO, at different pressure drop according to flow rate so the variation between the two different flowrate is less than in the original pic...The 2 flow rate are different in each tests so pressure drop is different too.
So what do you think?

I'm not sure if I understand what you're saying, but putting two identicle pumps in series does'nt increase flow rate does it?, just pressure...

True ! But more pressure pump give more flow rate (you are closer than theorical maximum flow rate of one pump, if you have a pressure head very very high your flow rate will be maximum of one pump in series) and so more pressure drop in the block. It's is the first goal to have more flow rate and to keep a decent flowr rate putting 2 pumps in series to "fight" again pressure drop of the block. But difference between one or 2 pump is not high.

Pressure drop curve of the block don't change only pump curves...There will be a equilibrium between the 2 curves at the common point of the pump curve and block curve and only that..


(Sorry for english :p )

Yeah Roscal, I think you're right (though I had to read your post twice to figure out what you were right about ;) ).