@ant: yes it could be smaller but with larger volume the tension of the air spring doesn't exponentially increase as fast, and their is only one schrader, that schrader is there for manual filling in case I later want to detach the feed or mess up on the pressure reducer I can instead do it manually, and if the pressure goes down you see the pressure reducer lacks any method of venting so I can just poke the schrader
@jack maybe so, but I can always just choose a higher pressure difference, 20psi should be fine right, btw thanks for the animation
but do you think it could be safe enough for a sealing face instead of the larger plug
EDIT: thought of a little revision stuff so I altered the diagram








