I'm looking for a combiner to proportionally mix water with two other aqueous solutions.  looking at flowrates of about 15 gpm and pressures of about 150 psi with a mix ratio of 16% of A, 16% of B and 68% water.  The flow rate of the water will not be consistent in the application so a solution that works proportionally within a flow range would be ideal.  I would also like the pumped water to do all the work (ie. drive the pump that injects the liquids).  Initially I was looking at using a gear pump flow divider in reverse but am getting steered away from the idea by our supplier who is concerned about the low pressures and use of water (not enough lubrication).  I'm not entirely convinced that the idea is bad yet as we could use nylon gears with some clearance gaps seeing as our pressures are low and leakages would be internal and tolerated.

Does anyone have any experience mixing solutions in an application like this?

Thanks
Charlie