Turing a non priming pump into a self priming/automatic priming pump

[DieselTwitch]

Hello,
I have never posted on this site before but find many answers to many questions i have on here.

No I have one to ask directly.

I have the need to install a pump for pond pumping and sump pumping. Im using 2" Motorized valves to select the source... not really part of my question i just wanted to give some background.

For a while I've been looking at 2HP Self Priming pumps.... Having that self priming is a very important thing however the pay off is a dramatic loss in pump efficiency. Best i can hope for with a Self Primer is 50% however with a regular centrifugal pump is 85%. So my idea is this. I want to use a bypass valve,

This valve

http://www.omega.com/Green/pdf/SV3500.pdf

to turn this pump:

http://www.wegotpumps.com/pdfs/87-88.pdf

into a self priming pump

Take a look at my drawing to see what I am thinking.

http://www.greenteksolutions.us/pumpidea.png

I need to know if this has any chance of working. the basic theory of this is that once the pump is primed i will see a dramatic rise in outlet pressure (measured by a pressure sensor) and the system will shut off the valve returning the pump to its high efficiency mode of operation.

Thank you for any help you have to offer.

 

[Artisi]

If water carry-over is a problem, use a water ring vacuum pump.