How can I obtain a tank of pure helium or nitrogen without looking suspicious

[ScorpiusDragon]

I feel like it would be suspicious if I walk into a store that sells something like party balloons and ask, "Does this have pure helium?"

 

[omw/2/ctb]

Apparently nitrogen has an interesting use among automotive impresarios, so you could pretend to be a motor-head and say you want nitrogen gas for your wheels...

Inflation of tires: Now a days use of nitrogen gas over normal air is quite common. There are claims that filling nitrogen alone instead of air help in smooth drive and also one need not check for inflation status for few months.

 

[TiredHorse]

Purchase gas from an industrial supplier, where it's pretty much a guarantee they don't adulterate the gas. Nitrogen, argon, or helium (they will all work for CTB) sold for welding, for instance, must be effectively pure or else it won't work. "Laboratory Grade" gas will be of the highest purity, but you'll pay through the nose for that last .04% of purity that is of negligible importance.

Helium sold to the public for party balloons should be assumed to be adulterated, by casualness or by intention, since purity doesn't matter so long as the balloons rise. I've seen accounts of nitrogen sold for beer or wine making to be of uncertain purity, so be cautious when purchasing from suppliers who cater to those markets.

Uses of inert gas:
Inflation of tires in cars and bicycles, as described
Making wine
Making beer
Welding, as shielding gas to prevent oxidization of the material being welded
Paint shop, to headspacing partial cans of expensive paint, preventing their skinning over and going bad (my other use for inert gas)
Long term bulk food preservation, to prevent loss of nutrients from oxidization and to deter insect/rodent depredation

 

[Purgatory]

TiredHorse writes as eloquently as ever! And is completely right. There are many reasons to purchase inert gasses. All of them legal. Most often, you won't even be asked questions.
As a professional mechanic, I will add to this that nitrogen in your tires is a gimmick. You may be told they put nitrogen in airplane tires. That is correct! (I am an aircraft mechanic. 25 years experience)
There is only 1 reason that nitrogen is used in aircraft tires. The brakes are magnesium. There is a fusible plug (a plug that blows out when it gets hot) that directs nitrogen onto a flaming brake to put out the fire, should a fire occur. Multi-ton aircraft landing at several hundred miles per hour cause a lot of stress on the brakes. Brake fires happen way more often than you think.
Back on subject, have no fear buying the gas. You are probably the only one who cares why you are buying it. Plenty of reasons to use if someone does care to ask! :)

 

[Jen Erik]

I ordered nitrogen off the internet, two tanks, two different times, no questions asked.

Delivered to my building's lobby.

The only iffy thing about the experience for me was a neighbor in my building who I do not know signed for the first tank, as I wasn't around. And then another neighbor who is a casual friend picked it up from the lobby and brought it to my door. The tanks shipped with 'hazardous materials' and 'non-flammable gas' stickers affixed to the outside box, so I have no idea what they may have thought. My friend didn't make any mention of it to me, other than to text to tell me they put it right at my doormat.

 

[Nitromask]

Order online from cyberweld