Energy grade line for a pump system

[theone]

Homework Statement

http://postimg.org/image/lb6hsi843/

I am trying to draw an energy and hydraulic grade line for this system. The gauge pressure is supposed to be 0 at the points shown and those are centrifugal pumps. What I don't know is how flow and pressure vary throughout

Homework Equations

The Attempt at a Solution

I think velocity increases at the discharge of the pipe in each section. But I don't know how the pressure changes along the suction and discharge lengths of the pumps.. Also, how does the pressure at the pump discharge reduce to 0 at the points shown

 

[mfb]

Assuming your fluid is incompressible, the same amount that flows in has to flow out. How can velocity increase?

Which kind of pressure change do you expect within the pipe sections, and between the sides of the pumps?