Help!!

What is on the discharge side???? Open ended or partial flow or is it variable? What is the design of the pump?

These are but a few of the questions that must be answered first.

Is this homework, or idle curiosity or work related?

If it's homework, that should be disclosed up front.

You will most likely get help either way.

I think this homework. Leaving the unknowns aside, I think you should read up on the continuity equation. You also need to use the momentum equation based on the properties of the pump.

I suggest the following book:

http://www.amazon.com/Transport-Phenomena-2nd-Byron-Bird/dp/0471410772

sorry guys, i just want to know if i let the bypass valve(in the middle) open or close, will there be any change on pressure and flow?? they told me that this can increase the pump capacity thats why they design it like this.. this has to supply water in a pipe 3" with a distance of 300meter, and need a working pressure of 3BAR. is there any chance you know a site that can help me with this one?? Thanks guys

Assuming the valves either side of the pump are both open:

• If the valve in the middle is closed, then there will be an increase in flow and pressure, though it is not possible to calculate it without knowing what is happening downstream of the arrangement, pipe sizes, branches, etc.
• If the valve in the middle is open, one might as well turn off the pump, as it ain't bringing much to the party and one could save a load of power.
• If the valve in the middle were to be a non-return valve arranged for flow from left to right, and a pressure sensor were to be installed downstream on the right, then one has the basis of a drinking water booster station, widely used throughout the UK!

If you can cram 200 gpm through that 1" discharge line, I'm pretty sure it will take more than 4.8 bar, no matter what sort of valve is implied by the symbol.