Ok, so I now have the solenoid, needle valve, and regulator... I'll need to get my hands on a bubble counter, but that can wait for a little bit.
I want to use swagelok pipe fittings for it, keep it easy to just order em all online.
From the reg:
-B-4-HRN-2 (Brass Pipe Fitting, Hex Reducing Nipple, 1/4 in. Male NPT x 1/8 in. Male NPT)
-B-2-SE (Brass Pipe Fitting, Street Elbow, 1/8 in. Female NPT x 1/8 in. Male NPT)
-Solenoid goes here
-B-2-ME (Brass Pipe Fitting, Male Elbow, 1/8 in. Male NPT)
-Needle valve goes here. (It's the Parker 2F-H3L-V-SS-TC, so it's straight thru, I want the straight thru to be vertical)
-B-2C2-1/3 (Brass Poppet Check Valve, Fixed Pressure, 1/8 in. MNPT, 1/3 psig (0.03 bar))
Then the bubble counter above this, probably a JBJ style.
Does this seem plausible? Am I missing anything?