Started with 1/4 " aluminum body solenoid valves, primary side of circuit they are fine, output side volume is on the low side, found some reasonably priced 1/2' plastic body valves, going to continue with testing with what I have(for control evaluation) until new valves arrive, I think the plastic valves will be better suited to wash down and decontamination , which is a primary concern. I am maintaining separation of the control and pneumatic arrangements to facilitate cleaning and servicing without exposing the control to inadvertent contamination.