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where to get helium?

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Unread postAuthor: potatoflinger » Mon May 05, 2008 7:31 pm

brogdenlaxmiddie wrote:
potatoflinger wrote:
Lentamentalisk wrote:I am lucky enough to know a guy who has an old gigantic helium tank that he used to use for welding. The thing is a BEAST. Its about 5' tall and weighs too much to be picked up by one person EMPTY!

Wouldn't it be lighter when it's full of helium?


smartass :D

No, I was wrong. (but I was kinda trying to be one :lol: )
Sorry about that.
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Unread postAuthor: Ragnarok » Mon May 05, 2008 7:44 pm

rp181 wrote:nope, helium is less dense then air, but when its lequified, its quite heavy.

Actually, helium isn't stored in liquid form, it's just stored as a very high pressure gas, like Nitrogen, air, oxygen and argon are when in tanks.
The only "common" gases (I can think of) that are stored as a liquid are Nitrous oxide, Carbon Dioxide, Butane and Propane.
I think Chlorine might also be, but it's not so common (for the general public at least)

Acetylene is an exception again, being stored as a dissolved gas.

It's nearly impossible to liquefy helium, given that it has a melting point of just 4 kelvin!!!
Getting solid helium is even harder, as you might expect - colder again, and extreme pressure is necessary.

As an aside, Liquid nitrogen isn't a practical way of storing nitrogen, it's only really used for cooling things, and not much else.
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Unread postAuthor: DYI » Mon May 05, 2008 7:59 pm

I think that some people may be operating under the assumption that helium has negative mass or something. :roll:

You can get tanks of liquid helium, liquid nitrogen, liquid oxygen, and even liquid hydrogen, and they do store far more than a high pressure gas tank for a given volume, but the cryogenic equipment, huge costs, and horrible consequences of failure put them out of reach for most of us.
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Unread postAuthor: Ragnarok » Mon May 05, 2008 8:08 pm

DYI wrote:I think that some people may be operating under the assumption that helium has negative mass or something.

"Hello, is that BOC gases? Yes, I need minus 10 kilograms of helium please... Oh, you don't have that little? Sorry for bothering you then."

:D
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Unread postAuthor: trae08 » Mon May 05, 2008 8:38 pm

boc gases dosnt exist any more.. they are linde gases now.

i have a boc helium tank which weighs about 100lbs or so empty and its about 5 ft tall. but to get it filled i have to go to airgas...
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Unread postAuthor: biggsauce » Mon May 05, 2008 10:05 pm

Where I work, we have two or three 300 gallon liquid nitrogen tanks. These are some impressive tanks to say the least. We use it for shrinking stuff like cylinder liners, crank rings, etc.

I may have a talk with bossman and see if we can get a helium tank for some lateshift fun :twisted:
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Unread postAuthor: rp181 » Mon May 05, 2008 10:05 pm

shouldve relized its not liquified, remebered this:
Helium in the liquid state is a superfluid. This means it has ZERO viscosity(no resistance to flowing), itle do anything to get to other patches of liquid helium, fo example, if you have a bowl inside a larger bowl, with the larger bowl with some liquid helium as well as the inner, the helium will rise up and climb into the inner bowl(or vice versa).

Unrelated, but i thought it was cool =)

On a related note, which would give more shots, a HPA tank to 4500PSI, or a same sized one with liquid CO2, im thinking the CO2.
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Unread postAuthor: biggsauce » Mon May 05, 2008 10:08 pm

On a related note, which would give more shots, a HPA tank to 4500PSI, or a same sized one with liquid CO2, im thinking the CO2.


PV=nRT would tell you for sure. I'm feeling sort of lazy right now as I've been studying for exams. Otherwise I'd do it, but its not hard to figger out :wink:
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Unread postAuthor: rp181 » Mon May 05, 2008 10:12 pm

it would help if i knew the variables =) is there some law i can look up?
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Unread postAuthor: Lentamentalisk » Mon May 05, 2008 10:15 pm

first of all, CO<sub>2</sub> liquifies at around 800psi or somewhere around there (may be more like 1200, not sure exactly.) HPA is at 4500psi. That should be answer enough.
Also, CO<sub>2</sub> is terrible in comparison to air for fast speeds. CO<sub>2</sub> has an atomic mass of 40g, whereas air has a mass of ~20% 32g (for O<sub>2</sub>) and ~75% 30g (for N<sub>2</sub>), so it air will have a much faster speed of sound.

PV=nRT has nothing to do with this
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Unread postAuthor: biggsauce » Mon May 05, 2008 10:20 pm

Lentamentalisk wrote:first of all, CO<sub>2</sub> liquifies at around 800psi or somewhere around there (may be more like 1200, not sure exactly.) HPA is at 4500psi. That should be answer enough.
Also, CO<sub>2</sub> is terrible in comparison to air for fast speeds. CO<sub>2</sub> has an atomic mass of 40g, whereas air has a mass of ~20% 32g (for O<sub>2</sub>) and ~75% 30g (for N<sub>2</sub>), so it air will have a much faster speed of sound.

PV=nRT has nothing to do with this


...then I must need some sleep, I'm not thinking straight...
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Unread postAuthor: Ragnarok » Tue May 06, 2008 5:28 am

trae08 wrote:boc gases dosnt exist any more.. they are linde gases now.

Hmm, that's not the case over here. BOC still exists as a company here - but it is now part of the Linde group. Still goes by the name of BOC gases.

Lentamentalisk wrote:PV=nRT has nothing to do with this

It does in a way, although Boyle's law is more appropriate.

It's not a particularly easy question to answer. However, I will make a guess.

In a CO2 tank, as a rough approximation, 3 litres of tank volume is 2 kilos of liquid gas - which at atmospheric pressure, is a little over 1000 litres.

A three litre HPA tank at 4500 psi will contain a little over 900 litres.

So, there's not a huge amount to separate the two tanks in terms of volume of gas. However, HPA will give better muzzle velocities.
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Unread postAuthor: Lentamentalisk » Tue May 06, 2008 5:41 pm

ooh, forgot about state changes... Rags got it right.
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