Sciencemadness Discussion Board

Nitrogen Supply-Tanks-Etc

zenosx - 12-11-2014 at 19:56

I have increasingly been getting into air sensitive chemistry and was curious where others in the US have obtained nitrogen supplies. He is readily available but is not nearly as inert as N2.
While there are plenty of welding suppliers around my area, they usually want a substantial rental fee for a very large tank, and the filling fee of course.

So, for those needing inert gas supply, how have you went about obtaining it, and in what supply do you obtain it? 1L bottle. 22L tank etc. I am looking for the most cost effective solution as I will only rarely use it, and do not have need for a full tank rental/etc.

Thanks for anyone's time!


As a side note I just purchased one of the AmScope microscopes so I will give a review once I've worked with it for a while

[Edited on 13-11-2014 by zenosx]

bobm4360 - 12-11-2014 at 23:49

He and Ar are both less reactive than N. K-Mart used to sell He in 5 gallon containers like propane bottles for filling balloons, so you might look at party stores. If CO2 is usable, it can be generated chemically or by sublimation of dry ice. If you use high-pressure bottles, you will need a regulator too; and, preferably, a flowmeter as well. If you know someone who does TIG or MIG welding, offer to pay for a fill (or $20 and a six-pack:P) if they will bring their bottle and regulator to your lab). Lecture bottles and their regulators are a rip-off unless you can borrow one from a school; they will cost more than rent, fill and regulator from the local welding supply.

Regards,
Bob

Oxirane - 13-11-2014 at 04:48

I have heard that balloon He is not pure He but instead it contains some amount of oxygen, CO2 or both, because people inhale it for fun, and this is to prevent them from accidentally suffocate. It is also to limit its usability for suicical purposes.

I recommend you to buy inert gas from welding supplies. Their gases are exactly what they state, because deviations would cause major problems in welding, and therefore, potential for disasters if the seams fail.

And also, Argon and Helium are substantially less reactive than Nitrogen: the latter will decompose to nitric oxide upon certain conditions and readily form nitrides with alkali metals, aluminium, etc. While Ar and He will not form compounds in any conditions.

I personally use Argon, because I also have a TIG welder, and it is much cheaper than Helium, but yet inert apart from N2.

WGTR - 13-11-2014 at 08:27

Assuming that you live in an area with a full service welding shop, go back and ask for the largest cylinder that they will sell you. In my area those are usually half the size of the regular ones, but they can be bought outright. Just do the math to see if this makes sense in your situation. Think about how they will be refilled, and who will refill them. Other shops may not swap out a cylinder that you bought from a different vendor; ask ahead of time. Make sure that the seller has been in the area for a while. If they go out of business, you might end up with a cylinder that no one will swap out for you.

Argon is your best bet, not only because it is inert, but it is also a heavy gas. It is easy to blanket a reaction with it. It is also commonly available from welding shops.

I personally use the boil-off from liquid nitrogen, but this is for a professional environment.

MrHomeScientist - 13-11-2014 at 08:37

I recently bought a 40 cubic foot cylinder of argon from one of the local Airgas shops. The tank is roughly 3 feet tall and 6 inches in diameter; small enough to be portable, but quite heavy. It cost about $120 for a full tank (plus $50 for a flowmeter), and when I run out I just exchange it for another full one for only $30.
I thought Airgas only sold to companies, but was surprised to find that this one had a show room where anyone can walk up and buy most anything. So they might be a source to try for you.

Magpie - 13-11-2014 at 10:25

Quote: Originally posted by MrHomeScientist  
I recently bought a 40 cubic foot cylinder of argon from one of the local Airgas shops. The tank is roughly 3 feet tall and 6 inches in diameter; small enough to be portable, but quite heavy. It cost about $120 for a full tank (plus $50 for a flowmeter), and when I run out I just exchange it for another full one for only $30.


I have done same:

argon cylinder.jpg - 109kB
Quote: Originally posted by MrHomeScientist  

I thought Airgas only sold to companies, but was surprised to find that this one had a show room where anyone can walk up and buy most anything. So they might be a source to try for you.


I wonder what they would say if you asked for a small tank of H2?

MrHomeScientist - 13-11-2014 at 11:43

Good question, I'll have to ask. One thing I should have done while there was ask what different gases were available. I did ask if they had liquid nitrogen, which would be great for my educational outreach activities, but alas they did not.

unionised - 13-11-2014 at 12:11

Quote: Originally posted by Oxirane  
I have heard that balloon He is not pure He but instead it contains some amount of oxygen, CO2 or both, because people inhale it for fun, and this is to prevent them from accidentally suffocate. It is also to limit its usability for suicical purposes.

I recommend you to buy inert gas from welding supplies. Their gases are exactly what they state, because deviations would cause major problems in welding, and therefore, potential for disasters if the seams fail.

And also, Argon and Helium are substantially less reactive than Nitrogen: the latter will decompose to nitric oxide upon certain conditions and readily form nitrides with alkali metals, aluminium, etc. While Ar and He will not form compounds in any conditions.

I personally use Argon, because I also have a TIG welder, and it is much cheaper than Helium, but yet inert apart from N2.


Can we put the "Balloon gas" myth to rest?
They don't add CO2 or O2 (Or H2 which i have also heard suggested).
It's helium- just not very pure. For example, when they are going to fill "real" helium cylinders, they have to flush the lines with helium before they start- the "used" helium ends up recompressed and stored. They pump it into cylinders as "balloon gas" but if there are more orders for party use than for industrial or scientific, they just fill up the bottles with Helium.
Similarly, when Helium cylinders are returned they will generally have at least some gas in them (they certainly should do). But the seller can't be certain that it's still pure- not a problem- pump it out + sell it cheap for filling balloons.

j_sum1 - 13-11-2014 at 14:47

Quote: Originally posted by unionised  


Can we put the "Balloon gas" myth to rest?
They don't add CO2 or O2 (Or H2 which i have also heard suggested).
It's helium- just not very pure. For example, when they are going to fill "real" helium cylinders, they have to flush the lines with helium before they start- the "used" helium ends up recompressed and stored. They pump it into cylinders as "balloon gas" but if there are more orders for party use than for industrial or scientific, they just fill up the bottles with Helium.
Similarly, when Helium cylinders are returned they will generally have at least some gas in them (they certainly should do). But the seller can't be certain that it's still pure- not a problem- pump it out + sell it cheap for filling balloons.
I did not know that. Makes sense. (I was under the impression that it contained impurities from the hydrocarbons it came from.)

chemrox - 13-11-2014 at 17:08

I have a small (painted red) tank for H2. I fill it at the same place as Argon and N2. H2S is available there as well. Also HCl if you don't want to make it but that requires a special regulator. AirGas is the company. They're all over the US.

Metacelsus - 13-11-2014 at 17:50

Do you need to be affiliated with a business or school to buy from Airgas? I've seen Airgas trucks supplying the University of Minnesota, so I know there must be a location near me, but I have no idea if I could buy gases myself.

bobm4360 - 13-11-2014 at 22:17

I buy my welding supplies and gases from Airgas OTC. A lot of their business is supplying large customers, like industrial plants, hospitals and schools, but they'll sell to anyone who walks in the door with money.
Regards,
Bob

MrHomeScientist - 14-11-2014 at 06:25

Quote: Originally posted by Cheddite Cheese  
Do you need to be affiliated with a business or school to buy from Airgas? I've seen Airgas trucks supplying the University of Minnesota, so I know there must be a location near me, but I have no idea if I could buy gases myself.

See my first comment above.

Metacelsus - 14-11-2014 at 09:17

Oops, didn't see that. I might want to buy some Ar, then.

bobm4360 - 14-11-2014 at 11:02

Quote: Originally posted by MrHomeScientist  
Good question, I'll have to ask. One thing I should have done while there was ask what different gases were available. I did ask if they had liquid nitrogen, which would be great for my educational outreach activities, but alas they did not.

Another source for liquid nitrogen is a large-animal vet, especially in horse or dairy areas.
Regards,
Bob

Dan Vizine - 14-11-2014 at 17:41

Where I live, the welding gas suppliers will also rent you cylinders. I pay my local Strate welding supplier $10/month rental on the T sized tank (the big one) holding my UHP argon. I'm sure that not everybody wants to try to transport a 140+ pound cylinder in their family car and, presumably, the smaller sizes rent for the same or less. The hitch is that we're zoned residential, and no gas suppliers deliver/pick up in residential zones.

About availability: nobody will bat an eyelash over hydrogen, helium, argon, Mapp gas, acetylene, hydrogen chloride or oxygen. Just don't ask for ammonia [because it can reductively aminate certain ketones, it's a red flag]. Check to see if your regulator (as low as $50 on eBay, maybe less) is the correct type. Fuel gasses have LH threads, O2 and inert gasses, RH threads. There are different sizes too, its all codified as CGA numbers. Make sure your regulator has the right size CGA threads. Corrosive gasses have special regulators, as mentioned earlier.

Locally, the charming folks at Praxair have been buying up all of the small shops that will sell out to them. Then they started what I imagine was the goal all along, upping prices with an irritating Steve Jobsian-like arrogance and tightening up on control of "ownership" of the cylinders. Luckily, they couldn't buy out everybody. Generally speaking, stick with small, locally-owned shops if you can. They help more you more, treat you better and charge the same or less than the corporate machine to whom your business is practically meaningless.


[Edited on 15-11-2014 by Dan Vizine]

careysub - 15-11-2014 at 04:56

Quote: Originally posted by unionised  
...
Can we put the "Balloon gas" myth to rest?
They don't add CO2 or O2 (Or H2 which i have also heard suggested).
It's helium- just not very pure. For example, when they are going to fill "real" helium cylinders, they have to flush the lines with helium before they start- the "used" helium ends up recompressed and stored. They pump it into cylinders as "balloon gas" but if there are more orders for party use than for industrial or scientific, they just fill up the bottles with Helium....


Even if the helium they are putting into the party gas tank were totally pure... they don't evacuate the tank first. The pressure in the tank is about 20 bar, 1 bar of which is the air that was originally in the tank. So the gas is going to be 5% air (4% N2, 1% O2).

Harbor Freight has 20 cu. ft. argon bottles for $90, if you are on their mailing list you might be able to pick one up with one their 20% off coupons (as I am planning to do this weekend).

[Edited on 15-11-2014 by careysub]