SpudFiles

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

No, I was wrong. (but I was kinda trying to be one )
Sorry about that.

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.

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

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.

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."

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...

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

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.

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

it would help if i knew the variables =) is there some law i can look up?

first of all, CO₂ 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, CO₂ is terrible in comparison to air for fast speeds. CO₂ has an atomic mass of 40g, whereas air has a mass of ~20% 32g (for O₂) and ~75% 30g (for N₂), so it air will have a much faster speed of sound.

PV=nRT has nothing to do with this

Lentamentalisk wrote:first of all, CO₂ 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, CO₂ is terrible in comparison to air for fast speeds. CO₂ has an atomic mass of 40g, whereas air has a mass of ~20% 32g (for O₂) and ~75% 30g (for N₂), 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...

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.

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