It is a very simple system and has been used by many cleaners and manufacturers over the years.So, if I'm understanding you, you have no chemical injector whatsoever? How in the world is the chemical being drawn into the system? I'm totally at a loss. Is the pump itself somehow drawing it and you're using the Dwyer to restrict it? If that actually works I wonder why nobody else on earth has figured that out or maybe they just enjoy making these machines as difficult as humanly possible to work on! Prochem, Hydramaster, Chemtex, and all the rest sure haven't made these chemical systems simple or easy to work on. I'm VERY interested in your solution.
The pump draws water (suction). By placing a regulator on the incoming water line to the pump you restrict or starve the water flow to the pump a little. When you starve the pump a little it is forced to draw it from elsewhere. In this case it draws it through a 2nd. line which is hooked to a dwyer meter and then the chemical jug.