What happens if the suction of a centrifugal pump is blocked?

[bgmalone]

I am using the rotating endplates of a submersible motor as rudimentary centrifugal pump surfaces to keep dirt out of the seal area of the motor. The endplates have radial slots cut in them as slingers. Filtered water is supplied at center of the endplates at the ambient pressure of the depth the motor is operating. The motor rpm is +/- 1000 rpm. To verify operation in all conditions I have allowed the filters to clog, using manometers and dye to characterize the flow characteristics has produced ambiguous results. Can a reference for centrifugal pumps be recommended that will help me understand the results of my tests?

 

[bgmalone]

To clarify what I am looking for with the pump suction question: Clearly the flow thru the pump reduces to zero, but without flow will the interior of the pump be negative of the output. For a given rpm, is this differential a limit based on geometry? Is it possible to predict this pressure differential? My empirical test results are ambiguous. When the "pump" plates are churning the water inside, the manometer readings appear to be influenced by dynamic effects. The manometers have very small orifices thru flat surfaces parallel to the pump plates but I do not get symmetrical data on both sides of the motor (the parts are symmetrical) or when reversing rotation.

Thanks!