Firehouse adapter for Omega bottle

Your adapter that comes attached to tanks with a male Foster QD is typically like the one on the right of this pic-

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so that would mean your tank without that adapter has a female DIN thread. A fire adapter to go from male DIN to Male CGA347 is now required, like to the left in that pic or here it is solo-

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airhog.com or airtanksplus.com has them, or you can try and source the two parts to make this one fitting thru amazon or any online dive shop parts house



the other adapter alternative if you were TO NOT remove your male foster fitting off of your tank is to:

find a male CGA347 that is tapped on the other end with female 1/8” NPT and then thread on a 1/8” male NPT to female QD foster and you can leave what’s on your tank in place and the fire station can “hook you up”

or a male CGA347 with a male 1/8” NPT that will accept a female 1/8” NPT QD foster. To be honest, I have yet to find this type of CGA347 adapter, as they typically come instead with 1/4” male NPT. 
I like to get to from one thread type to the next without stacking adapters on top of adapters, couplings, etc. with all these threaded joints mixed in with all types of different steels and now you got an ensemble of fittings that you hand the guy in the fire station that’s a foot long. He’d think you went to your local ACE hardware to source your high pressure air parts, lol, and decide to not fill your tank!
Rookie move in my opinion.