Is the viscosity of the fluid critical? Could changing the surface tension of the foam bubbles with an alcohol work?
Viscosity is usually about 1cP @ 25 C. We'd rather not introduce an alcohol into the mix, because then the contents of an 'alcohol-free' formula would have to be re-labeled, as per FDA regulations. Our ( temporary ) solution has been to withhold agitation of the mixture, until the orifices of the mixing tube are at least 6 inches below ( 85 gal. ) the liquid's surface.
Normally, the mixing vessel would be pre-filled with approx. 100 gal. of water, then the first chemical would be added. As the second fill sequence/ line flush was started, the mixture would be recirculated through another line going through a diffusing tube, to ensure that the solution was thoroughly mixed. This recirculation continued for the duration of the chemical addition/ water fill sequences, and remained active, until an operator terminated the operation, so that the mixture would then be pumped to the remote containers.
This had never been a issue, because the mixing was done with mechanical agitators, not recirculating pumps. The pumps are more efficient, but they aerate the solution quite a bit, causing the foam.
We've tested delaying the recirculation, and it looks promising, so we'll do that, for now.
I do appreciate your help, though!