On Monday, May 29, 2017 at 1:04:44 PM UTC-4, wrote:

u
Thanks, Dan. I read that -- and maybe 100 more pages over the past few days. None of them really explain it. To say that the energy is derived from the impeller is axiomatic. It doesn't explain what's going on inside the second stage.

Rather than try to go through it in detail, I'll post something if I find a good explanation.

--
Ed Huntress

Try not to make it complicated. Say you have a centrifical pump rated at 5 gal per minute at 10 psi pressure. Well the pump when used really has a input pressure of about 14.7 psi. That is just atmospheric pressure. Now add a second pump with the same specs. Put the two pumps in parallel and you get 10 gal per minute at 10 psi output pressure. Put them in series and you have 5 gal per minute at 20 psi. It really does not depend on them being centrifical pumps. The same applies to gear pumps , turbine pumps, diaphragm pumps, etc.

What goes on in the second stage is exactly what goes on in the first stage..

Dan