Green Gauge? + Sanity Check

I nabbed a group of regulators on ebay. Most are Cornelius brand, so I know I'm safe there. My concern comes with one secondary regulator that is branded USG (US Gauge) and has a green gauge (see pic below). When I go searching for this online, the green regulator seems to be associated with medical equipment. Is that correct? If so, is it safe to use with beer/soda?




Also, just as a sanity check, does this setup make sense:


I have a primary regulator that will be attached to my 20lb tank. I'll reduce that regulator to soda pressure and use a y to split that line. One side will go to the soda keg, the other will go to the grouping of secondary regulators, further reducing for the three main styles of beer. Considering the regulators came with all different psi gauges (60, 100, 160) I'm going to replace the three low pressure beer gauges with 30psi. Down the road if I plan on having more than one beer of a style then I can split the air after each regulator.

My setup would look something like this:

Your diagram shows the regulators as secondarys. Are they actually secondary or are they primary regulators? Look at the sticker on the Cornelius regulators. If it says min inlet pressure 500 psi they are primary not seconday regs. I just want you to be sure of what you have.

They did say min inlet 500 psi, so they are not "true" secondary regulators. Thanks for saving me some headache. I'm assuming that the problem with how I was going to use them was that I was planning on dialing down the pressure to 30 psi for the soda, and 30 psi is nowhere near the min 500 psi inlet?

So what if I configured it this way instead:



With the high-pressure hose going directly into the chain of regulators I should have the min psi needed. From what I've read the high pressure just goes right through to the next regulator, so I shouldn't have issues there if I'm understanding this correctly.

That is correct a single stage line regulator with a third output will just pass through the HP onto the next one. The only reason you would need a two stage before that cascade of regulators would be if they were all LP line regulators.