I would recommend getting compressors and a tank. Simply because i just swapped over from running nitrogen, and yes it was a very clean setup but it was no where enough air to supply the nathan horn. Also i was tired of pulling out the nitrogen bottle every two weeks to refill it. It is even cheaper in the long run to just go ahead and purchase the compressors and tank.
I’ve thought this through recently.
I have a SCUBA tank that would work nicely.
I am a member of a Volunteer Fire dept but I don’t think they’ll let me fill up there 
I was thinking about selling my subs, PA, and shocker kit to get a k3 and power it with my SCUBA tank :D:D:D
Exactly. Why pay to refill, when after you buy a compressor it cost you nothing!
dood to each his own… maybe SOME people dont have room for a tank and compressor… co2 would be a good choice … and maybe some people have a horn that can handle more air than a compressor can take more air than a compressor can put out… example the kahlenberg d3 i was rated for 300 psi… cant get that from a compressor… yes a compressor gives you an endless airsupply but dosent exactly cost you nothing… you have high start up cost… but in the end its cheaper… yes…
but co2 tanks are everywhere and usually can get a co2 setup used for maybe a 1/4 to 1/2 of the cost of a compressor setup… easier to setup, no compressor noise and space saving but cost to refill…
so there are cons to every setup… and as the guy posted above “A 80 cu ft scuba tank at 3000 psi is egual to a 60 gal air tank at 146 psi” you gonna get a 60 gal tank in a compact car? nope…
so dont bash everything man…
Not trying to bash, just stating my opinion. I didn’t think of a horn needing 300psi, but that would be a very ideal way to supply that horn with air. Good thinking right there.
I’ve thought about this idea as well. I’am a firefighter and I can easily get an old SCBA bottle to use. The SCBA would only feed into my 20 gallon tank because you wouldnt be able to get enough volume to run my nathan and leslie. It would cost me nothing to have it filled at the hall and it only takes a few mins to fill up a tank. The only down side to it is finding a regulator that doesnt cost 300-400$. Does anyone know where I can fing a high pressure regulator for a decent price. I’ve looked at Graingers and on the internet but havent found anything good yet.
ebay
I am doing the same thing as you. Got a free air bottle from work, can fill for free since I am there every 3rd day. I bought a Gentec regulator for just over $80 shipped from toolfetch.com It is a max input of 4000psi and max output of 300psi.
Bought me a bottle bracket off ebay for about $40, almost the same as we have in our trucks. And then the rest is the same as any other install.
I have a compressor/tank setup on my jeep and it is very nice for tires, tools, horns, etc. But I hate hearing the thing refill all the time. The scba bottle is going in my daily driver that I dont want to wire/hear a compressor in.
Ok thanks man…ill have to check it out
Try a welding supply.
Does anyone have this setup? I need some pics/info on the junction of the scuba regulator, an the airline going to the horn.
Ive been to the scuba shop, and they said that Im gonna have to order a special fitting for the scuba regulator, to run a bigger NPT fitting…
I have a nathan k3, an I want to run 1/2" line, but I wonder if the scuba tank will be able supply enough air, because the size of the outlet on the regulator is very small.
Any info would be AMAZING! I have my tank and regulator, an needless to say Im ready to hook this baby up!! lol
I know it’s been two years, but is this the one you got?
http://www.toolfetch.com/Category/Welding/Gas_Cutting_Welding/Regulators_Flowmeters/331-190CD-45.htm
I don’t have a scuba tank yet, so I’m not entirely sure what I’ll be working with. Just trying to get my ducks in a row. Thanks!