Pressure Fluctuations In Mixing Head

Hello.

I am a chemical Engineer working for a polyurethane foam manufacturer. I have acome across a situation where I need help. can you help in giving answer or direction to the following situation ?

CASE STUDY"
I am pumping high viscosity resin (about 30000 cps) from a tank into a mixing head. Along with this resin, there are several other (5 to 10) feed streams coming into the mixing head. I have a pressure gauge after the pump in the line feeding the mixing head. The pressure on this gauge is very steady (fluctuates about 1 psi and operates at about 220 to 250 psi) when I am mixing at about 4000 rpm for a given through put rate. For the same throughput rate, when I increase the mxing speed, the pressure is not constant and keeps fluctuating as much as 12 to 30 psi. ( The operating range increases by about 20 psi). This fluctuation in pressure is the cause of inconsistent product coming out of the mix head. What causes this fluctuation and how can I minimize it? The mixer is driven by a 50 HP hydrulic drive.

Thank you for your help and look forward to some "direction" on where to seek the solution.

B. Patel
Plant Engineer

email: RMPIntL@aol.com