Nitrogen ?

Go pick it up at the store - Its an inert gas and there are no restrictions that I know of

But what is the pressure in the tank of Nitrogen? Its used for TIG welding. Id be surprised if its over 3,200. psi

They are very heavy. 

And they do offer 6000psi for industrial testing and aircraft applications. The tanks are likewise MUCH heavier than TIG tanks. The wall thickness is around an inch of I remember right. 
 
It was a 6,000 psi tank. I gave up. At 65 years old, I'm too old to wrestle with a 400# tank. I do have a Bauer Junior II compressor, and all 3 sizes of Joe B tank. I also have a Joe B regulator (6,000 psi). I did however decide to add an Ayrtekk booster, because I have two Huben K1's that can fill to 5,000psi, and a Benjamin Bulldog that eats a lot of air.
 
I talked to the local Airgas location this morning and he is supposed to be sending me a quote on tank rental and fills. He said the 6000psi tanks weigh 300lbs and would be tough to load and unload from my pickup. From what I have seen looking online a regulated fill station will run about $400 and not sure I would be comfortable filling without the regulator. I hope to hear from him of the lease and fill costs this afternoon.





tT
 
Is is usually a 6k tank, and they are heavy!

I get mine from Airgas for $75 yearly rental, and $75 per fill. Apparently, the local place sets prices. They did try to raise my price this year, but I was told to push back and they caved. 

They won’t deliver to a residential neighborhood for me either, even though I’m in the country, and it is just a couple of us on the road. He and I put the first one on my pickup when we got it, and my wife and I barely got it out. I have a dolly to move it. First time I went to take it back, I thought we could get it in the truck... NOPE! So I just strapped it down to my utility trailer and carried it back and picked up my new one on the trailer. They said others do the same. 

I picked up the $200 assembly from JoeB and I fill to my Tiger Shark tank, until the pressure gets low enough to fill directly to the guns. The $500 assembly is only really needed if you want to fill guns directly from a new tank.
 
I will Harry. Might take awhile though. The Ayrrtek booster is backordered for 2 weeks (we’ll see). I’m not even sure I will get all the way to 5,000psi, again we’ll see. Even 4700psi or more would be nice. When I fill my 4,500psi tank, by the time it cools, it’s usually less, more like 4300psi and then only for a few fills, so I’ll try the booster. I was going to buy another Great White tank from Joe B, but with my Bauer Junior II and 3 Joe B tanks, it would give me more volume, but not any higher pressure, so I figured the booster was a better place to put the money at this time. Really was hoping to go with a 6000psi nitrogen tank, but with no residential delivery, I decided against it.