Argon vs Nitrogen for a strut

manac

manac

Pre-takeoff checklist
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Manac
Any issue substituting argon for nitrogen in a strut?
I’m set up with argon for my tig welder and don’t want to set up another gas.
I just run air for tires but can see the value of moisture free gas for a strut.
 
I don't know of any incompatibilities with the strut materials. Argon is an inert gas, my opinion is that it's fine. But I'm not an A&P, just another pilot.
 
manac said:
Any issue substituting argon for nitrogen in a strut?
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TC or E/AB aircraft? Don't know about the gas chemistry difference, but anytime there is a substitution of material on a TC aircraft it is considered an alteration which requires an APIA to be involved.
 
I do not see an issue with it either, that said my nitrogen bottle kit has come in handy on several occasions. If you have a tig, you might find it useful as well. You might need a new regulator for your argon anyways to service a strut.

An argon bottle got mixed up in our nitrogen bottles at work. The guys that serviced tires with it were convinced they had bombs on their hands. :rolleyes:
 
I would think any inert gas would be fine, but argon is awfully expensive compared to nitrogen. I got a 20cuft n2 cylinder to keep in the hangar, figuring that would last me a long time. I topped off the struts & tires on my piper once, and I'm down to 1000 psi. I may need to switch it out for a bigger one. It was like $5 or something for the gas though. It's cheap enough i decided not to buy an air compressor for up there.
 
Bacho said:
I do not see an issue with it either, that said my nitrogen bottle kit has come in handy on several occasions. If you have a tig, you might find it useful as well. You might need a new regulator for your argon anyways to service a strut.

An argon bottle got mixed up in our nitrogen bottles at work. The guys that serviced tires with it were convinced they had bombs on their hands. :rolleyes:
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Why did they think they had bombs? I'm not understanding something here.
 
What's wrong with plain old air. Been using it for 70 years no problem. Isn't argon a noble gas meaning it doesn't want to combine with anything which means it greatest danger is to your bank account.
 
The argon molecule is bigger than a nitrogen molecule so it would tend to leak out at a slower rate. That being said, it is also more dense so it might affect the dynamics of the strut slightly.
 
Joe_B1 said:
The argon molecule is bigger than a nitrogen molecule so it would tend to leak out at a slower rate. That being said, it is also more dense so it might affect the dynamics of the strut slightly.
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Is argon a molecule as it comes from a gas tank?
 
Cap'n Jack said:
Is argon a molecule as it comes from a gas tank?
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Argon and the other inert/noble gases (He, Ne, Ar, Kr, Xe, Rn), do not form molecules in their free state like oxygen (O2) and nitrogen (N2) do. Their "inertness" in forming compounds (molecules) extends to themselves because their electron shells are fully occupied.
 
Snowmass said:
What's wrong with plain old air. Been using it for 70 years no problem. Isn't argon a noble gas meaning it doesn't want to combine with anything which means it greatest danger is to your bank account.
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Yes. In the old flight school days it was all air. If a small jet or prop headed our way we’d run out for nitrogen. KISS, in this case. I do however see the difference between a beater trainer plane vs. your glorious baby who deserves nothing but the best.
 
Ultimately, it would be better, though we only used nitrogen (which is anything but inert!).
 
The atmosphere is nearly 80% nitrogen but I don't have a (gear) leg to stand on in this debate as mine uses none ...
 
kgruber said:
I've never seen a strut rust from the inside out. I just use air.
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Makes sense, I have a really good dryer for my plasma cutter, I’ll just pull air from after that. Plasma cutters hate water.
 
Hang 4 said:
It would be an Atom, not a molecule.
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Domenick said:
Argon and the other inert/noble gases (He, Ne, Ar, Kr, Xe, Rn), do not form molecules in their free state like oxygen (O2) and nitrogen (N2) do. Their "inertness" in forming compounds (molecules) extends to themselves because their electron shells are fully occupied.
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Thanks, I was merely trying to be a bit nicer about small errors in threads.
 
Argon (Ar, MW=40) will diffuse about 20% slower than nitrogen (N2, MW=28) according to Graham's Law, so that is a bonus for inflation longevity. (Diffusion rates scale with the square root of molecular mass.) Argon has only about 70% of the thermal conductivity of nitrogen or oxygen, but I suspect that may not be a major factor for tires or struts that have intermittent heat loading. But heat dissipation will be significantly slower with argon. Both argon and nitrogen are highly inert. Nitrogen rivals the noble gases for chemical inertness under a wide range of conditions, for which you can blame its very strong triple bond.
 
Kenny Phillips said:
Ultimately, it would be better, though we only used nitrogen (which is anything but inert!).
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Nitrogen the molecule is pretty much inert. It takes a lot of energy to break the triple bond and get it to react with anything else.

Compounds containing nitrogen atoms can be a lot less inert, but one wouldn't be filling struts or tires with them.
 
Rgbeard said:
Shouldn't we calculate which gas would be lighter, and consider using that choice?

Have a better usable load as a result, I'd believe. ;)
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This is why I use helium in my struts. I tried hydrogen, but there were just too many fires.
 
Jim K said:
This is why I use helium in my struts. I tried hydrogen, but there were just too many fires.
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I already proposed that sometime with the tail section (and wings) filled with bags of helium. You get 1.02g of lift per liter of helium volume. If you could get 100 cu ft of helium inside the airplane, you would get round about 6.25 pounds of lifting force. Not terrible, but pretty weird think to try to do.
 
Daleandee said:
The atmosphere is nearly 80% nitrogen but I don't have a (gear) leg to stand on in this debate as mine uses none ...
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I’m going to become a millionaire by collecting the nitrogen out of half flat tires (since the nitrogen doesn’t leak out, what’s left in a half flat tire, must be nitrogen, right?) and then sell it to suckers for big bucks. Well, except I’m lazy and would rather just laugh at them.

seriously though, if you keep refilling with 78% nitrogen, and what leaks out is the stuff that’s not nitrogen, it shouldn’t take long to end up damn near nothing but nitrogen in there.
 
So I did the math. If you refill your tire with air 3 times you’ll have 99% nitrogen in the tire. If, it’s true that nitrogen won’t leak out. The guy that came up with snake oil is rolling over in his grave.
 
Salty said:
seriously though, if you keep refilling with 78% nitrogen, and what leaks out is the stuff that’s not nitrogen, it shouldn’t take long to end up damn near nothing but nitrogen in there.
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I think part of the argument is that oxygen is a reactive species, and will degrade the rubber on the inside of the tire faster. Although oxygen is degrading the rubber from the outside at essentially the same rate, but for a minor bump in speed inside due to the pressure in the tire.

I've got a few degrees in chemistry which allow me to cogitate on the importance of such factors.

I fill tires with air.
 
The adiabatic compression of a monotonic (single atom per molecule) argon filled strut will be slightly different (which way I don't recall) from a diatomic nitrogen filled one. The gamma in an adiabatic compression is different for a monotonic gas vs a diatomic gas such as nitrogen. It is scary to try to find the actual numbers in an engineering reference book, and I swore off that stuff 65 years ago. Ignore....
 
nrpetersen said:
The adiabatic compression of a monotonic (single atom per molecule) argon filled strut will be slightly different (which way I don't recall) from a diatomic nitrogen filled one. The gamma in an adiabatic compression is different for a monotonic gas vs a diatomic gas such as nitrogen. It is scary to try to find the actual numbers in an engineering reference book, and I swore off that stuff 65 years ago. Ignore....
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I think both argon and nitrogen will be nearly ideal gases at tire inflation pressures. Even at higher pressures, the Van der Waals coefficients for nitrogen and argon are similar. In other words, air, nitrogen, argon, or any other ideal gas will have basically the same PV properties as one another. The only significant differences between ideal gases at ambient temperatures and pressures are thermal conductivity and diffusion rates, which are molecular-mass-related. You can inflate your tires and struts with helium or neon or xenon or sulfur hexafluoride (a nontoxic gas with a MW=146) if you want and you won't be able to tell the difference in performance, but the helium will leak out pretty quickly. (Amazing thermal conductivity, though.) Air is cheap and readily available. The benefit of using a inert gas for tire inflation is minimal.
 
Yes. Helium apparently can even leak through glass. This caused a problem with heat seeking missiles at Hughes.
 
Which is why we have a national defense helium reserve. It was / maybe still is imperative in the missile program because helium would be used to detect leaks.
 
WDD said:
Which is why we have a national defense helium reserve. It was / maybe still is imperative in the missile program because helium would be used to detect leaks.
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i thought it went away?
 
Still kicking. Was being phased out, but congress extended it in 2013. And yes it has lead to a public helium shortage from time to time.
 
PaulMillner said:
i thought it went away?
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I thought so too, but we were wrong. The BLM actually created a price spike in the global market for Helium, so now congress requires the BLM to sell off a portion of the reserve each year to keep prices steady and supply at sufficient volume.

Wikipedia ----

By 1995, a billion cubic metres of the gas had been collected, and the reserve was US$1.4 billion in debt, prompting Congress to begin phasing out the reserve in 1996.[4][5] The resulting "Helium Privatization Act of 1996" (Public Law 104–273) directed the Department of the Interior to start selling off the reserve by 2005.[6]
By 2007, the federal government was reported as auctioning off the Amarillo Helium Plant. The National Helium Reserve itself was reported as "slowly being drawn down and sold to private industry."[7] However by early 2011, the facility was still in government hands. In May 2013, the House of Representatives voted to extend the life of the reserve under government control.[8]
 
Threads like this are why I love this place. I came for the airplanes; I stayed for the minutia, pedantry, and thread drift.
 
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