Compressing helium

[abvpaintball]

Is it safe to compress helium to 4500 psi, ? Whats the dangers you might incounter using helium?

[TKM]

And ask weird questions.

[Blue]

I’d call your local welding supply co and ask them.

[incredablehefey]

Is it safe to compress helium to 4500 psi? Yes Whats the dangers you might incounter using helium?None that differ drastically from any other inert gas contained at that pressure

https://en.wikipedia.org/wiki/Helium

"Helium (He) is the second lightest elemental gas next to hydrogen. Colorless, odorless, tasteless, non-toxic and chemically inert, helium is non-flammable and has a high thermal conductivity. It is used to create an inert gas shield and prevent oxidization during welding of metals such as aluminum, stainless steel, copper and magnesium alloys."

[Dnele928]

Tougher to keep contained...small atoms. Wants to leak around seals.

Despite the Wiki reference, Argon is more practical to use for weld shielding.

Argon is heavier and easier to keep and control. Also inert.

[incredablehefey]

Tougher to keep contained...small atoms. Wants to leak around seals.

Despite the Wiki reference, Argon is more practical to use for weld shielding.

Argon is heavier and easier to keep and control. Also inert.

Yep. there are better choices for certain applications. I was just showing how inert it is. If it can be compressed in 6000psi tanks and blown into welding bead its about as safe as can be.

"Helium as a replacement for CO2 in GMAW of steel might work well in some applications. The presence of helium results in less fumes, good wetting action, higher deposition rates, and a flatter bead profile.

Helium is a key ingredient of gas mixes for GMAW aluminum or stainless steel. Typically, an old-school welder might use 100 percent argon when GMAW aluminum, but the addition of helium to the gas mix can result in better wetting. The negative is as the percentage of helium is increased, arc instability and spatter also increase."

https://www.thefabricator.com/article/consumables/rethinking-weld-shielding-gas-selection

[edgerly779]

^^^ This is about airguns not welding.

[scoutpup99]

Biggest question is why. Helium is expensive to purchase. My last bottle 220scf cost over $600 3 years ago. I don't believe they have increased the availability of helium since the government closed down and sold off its huge stock of bulk helium.

If you have a pressure vessel that could contain the helium at that pressure it would be fine.

I would use a less expensive alternative like CO2, nitrogen, argon, or one of the other inert gasses.

[Blue]

^^^ This is about airguns not welding.

[Revoman]

Yeah, helium is harder to contain and requires specialty valves that won't leak through. It's molecules are very small compared to other gases and is not easily contained other than specialty pipe, fittings and valves. Not saying it can't be done, we do it regularly, but for the layperson, definitely a different task to contain.

[Cokebottle]

Biggest question is why. Helium is expensive to purchase. My last bottle 220scf cost over $600 3 years ago. I don't believe they have increased the availability of helium since the government closed down and sold off its huge stock of bulk helium.

This.

Helium is recovered from uranium mines. Very expensive.

There would be no advantage to using it in an airgun. A cylinder of helium at 4500psi would be pretty much the same weight as a cylinder of Argon or air at 4500psi. CO2 would be heavier because of its condensation into a liquid, but this also allows for more CO2 to be contained in the cylinder.
Helium is difficult to compress.

[rivraton]

This.

Helium is recovered from uranium mines. Very expensive.

There would be no advantage to using it in an airgun. A cylinder of helium at 4500psi would be pretty much the same weight as a cylinder of Argon or air at 4500psi. CO2 would be heavier because of its condensation into a liquid, but this also allows for more CO2 to be contained in the cylinder.
Helium is difficult to compress.

The cons out weight the pros but strictly speaking on a performance basis helium does outperform compressed air by about 50 to 60 percent. (Some say even higher) Higher velocities and higher energies have been been achieved by just switching from HPA to helium, because of more rapid expansion...

[Crosman999]

To answer the "Airgun" part of the question. Yes it is safe, need a booster pump to bring up to PCP operating pressure. It will leak through the seals slowly so not something you would expect to leave the gun charged with. Using helium will produce huge amounts of power, many of the Big Bore guys use it to produce huge fpe #s. It's a good choice for inefficient Big Bores. I see no worthwhile gain as it's not something you can do with a field gun.

[abvpaintball]

Ya I figured its like nitrous in cars not everybody wants it as theres xtra cost , I make HPA and boost it to 4500 with no problem so someday I may try it just to see which guns I have will benefit from it

[foxtrotuniformlima]

This.

Helium is recovered from uranium mines. Very expensive.

Actually, it is a by product of natural gas production.