Have a look at this thread: http://www.fightingrobots.co.uk/thre...-featherweight

Should cover most things you need for a LP setup.

As mentioned above you need a safety valve, set at the lowest rated component in your system (probably 8bar)
And though the barb fittings you're using should be fine I'd prefer the push fit quick disconnect type. Much easier to take apart if need be.