The problem is that we don't know how to figure out how much pressure drop or liquid velocity is required in order to effectively shear this powder into the liquid. I'm guessing that as your pressure drop decreases, the suction of powder into the pipe is going to decrease as well, but I'm wondering if there is some sort of relationship that will give more details on this. One thing that is important to know as well is that as the starch powder comes in contact with brine, it will form fish eyes or clumps of starch powder that are hard to disperse or mix. Therefore it is desirable to obtain the best shear as possible in order to prevent these fish eyes from forming as soon as the powder contacts the brine.

Here is some more info on the setup:

Pipe inlet: 4"
Orifice size: to be determined
Brine specific gravity: 1.2
Brine viscosity: 2 cp
Final brine/starch solution viscosity: 200 cp
Desired Flowrate: 1000 gpm (this could be changed)
The pump we have currently can put 120 psi on the line, but this could be changed as well if required.