Argon in tyres?
#52
Sir Fallalot
Join Date: Jul 2006
Posts: 5,286
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 13 Times
in
11 Posts
Size isn't the only factor -- polarity will affect the diffusivity as well.
I think you should fill your tubes with UF6, which has a very low speed of sound. That way, everytime you braked you'd get little sonic booms in your tires.
**for all you physicists out there: yes, I know. work with me here...
I think you should fill your tubes with UF6, which has a very low speed of sound. That way, everytime you braked you'd get little sonic booms in your tires.
**for all you physicists out there: yes, I know. work with me here...
I think there are two issues here, for the technically inclined. First, how soluble is a gas in rubber tires? Second, how fast do the gas molecules move through the rubber once it is taken up in the rubber -- that is, what is its diffusivity? These are both functions of the gas's and the polymer's (in this case, rubber) chemical composition, as DMF pointed out, but are fundamentally two different properties. When these two factors are combined, engineers refer to the overall permeability, which is the mass flux (of the gas through the rubber in this case) per unit area per unit time, normalized according to the pressure drop across the rubber.
I did some google searching, and found a paper: Barrer, R.M. "Permeation, diffusion, and solution of gases in organic polymers." Trans. Farad. Soc. 35 628. It shows that the permeability of argon -- and thus how fast it will leave through the tire rubber, given the same pressure, tire thickness, etc. -- is about three times that of nitrogen. The units for this permeability look a bit goofy, but just take note that the outflow rate would be measured in "moles" or number of molecules, because it is this that determines pressure in the tire.
Some of the replies to this post indicated it might be a waste of time. Don't worry, OP, I think it's an okay question! In fact, I can remember an exam question some time ago regarding patents that Air Products, Inc., (in Allentown, Pa.) had filed for a gas that could be used to pressurize tennis balls. They claimed that the gas increased the usable life of the tennis balls by a factor of two or something like that. I guess I would argue that questions like these, then, can be fruitful/significant!
[EDIT: The tennis ball invention is US Patent 4,358,111.]
I did some google searching, and found a paper: Barrer, R.M. "Permeation, diffusion, and solution of gases in organic polymers." Trans. Farad. Soc. 35 628. It shows that the permeability of argon -- and thus how fast it will leave through the tire rubber, given the same pressure, tire thickness, etc. -- is about three times that of nitrogen. The units for this permeability look a bit goofy, but just take note that the outflow rate would be measured in "moles" or number of molecules, because it is this that determines pressure in the tire.
Some of the replies to this post indicated it might be a waste of time. Don't worry, OP, I think it's an okay question! In fact, I can remember an exam question some time ago regarding patents that Air Products, Inc., (in Allentown, Pa.) had filed for a gas that could be used to pressurize tennis balls. They claimed that the gas increased the usable life of the tennis balls by a factor of two or something like that. I guess I would argue that questions like these, then, can be fruitful/significant!
[EDIT: The tennis ball invention is US Patent 4,358,111.]
Best two posts in the thread, so far. Thanks guys!
Last edited by wroomwroomoops; 08-21-07 at 10:26 PM.
#53
Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Posts: 27,362
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Mentioned: 152 Post(s)
Tagged: 1 Thread(s)
Quoted: 6219 Post(s)
Liked 4,218 Times
in
2,365 Posts
A butyl rubber (or latex for that matter) tube is not an impermeable membrane, i.e. it has lots of little holes that allow gas to pass out of it. For CO2, the gas dissolves in the rubber and, like a wet cardboard...sorry...corrugated fiber board box, the CO2 seeps out. Basically, it just passes through.
However the tube isn't going to hold any gas forever. For the other gasses, the holes and channels that make up the box just take a little longer to get through. Kinda like when you put oil in that box. The oil will eventually seep out but it will take longer because it doesn't dissolve in the box. The loss of pressure in the tube is driven by the Principle of Le Chatelier. In a nutshell, Le Chatelier's principle says that any system not at equilibrium will try to get to equilibrium. As my old chemistry teacher put it, "Every thing goes the way the wind blows." The tube has channels and holes that allow gases to pass in both directions. Gas can go in and go out, albeit slowly. Since the pressure in the tube is higher than the pressure outside the tube, the gas tends to go out rather than in, i.e. that's the way the wind is blowing
Put any gas in the tube under pressure and it's going to find a way out. Helium and CO2 will find a way out rather quickly (on the order of hours), air (78% N2 and 19% O2) will find a way out in a matter of days. N2 by itself is going to have pretty much the same rate. O2...well, I don't know but putting pure O2, a oxidizable organic polymer, and heat together is likely not a combination I'm going to test any time soon I think I'll stay away from methane for the same reason. Boomba! Boomba!
Other exotic gases might take less time or more time than air. It's kind of hard to predict. But the problem with any gas is that you'll have to fill the tire from time to time. Exotics are exotic because they are rare and difficult to isolate. Therefore they cost more. And the benefit is probably pretty low. Air and a pump are still pretty economical.
Now if you want to do something, design a better tube. Mylar is far less permeable than rubber. It'd hold gas for a very long time but it has no puncture resistance and no...zero...nada...zilch elasticity. Urethane was tried for a while and it works...sorta. It's not as elastic as rubber, it holds pressure slightly better, it has better puncture resistance than mylar but less - way less - than rubber, and it is a royal pain to patch...and costs around 5 times as much as rubber. Not a whole lot of plusses
However the tube isn't going to hold any gas forever. For the other gasses, the holes and channels that make up the box just take a little longer to get through. Kinda like when you put oil in that box. The oil will eventually seep out but it will take longer because it doesn't dissolve in the box. The loss of pressure in the tube is driven by the Principle of Le Chatelier. In a nutshell, Le Chatelier's principle says that any system not at equilibrium will try to get to equilibrium. As my old chemistry teacher put it, "Every thing goes the way the wind blows." The tube has channels and holes that allow gases to pass in both directions. Gas can go in and go out, albeit slowly. Since the pressure in the tube is higher than the pressure outside the tube, the gas tends to go out rather than in, i.e. that's the way the wind is blowing
Put any gas in the tube under pressure and it's going to find a way out. Helium and CO2 will find a way out rather quickly (on the order of hours), air (78% N2 and 19% O2) will find a way out in a matter of days. N2 by itself is going to have pretty much the same rate. O2...well, I don't know but putting pure O2, a oxidizable organic polymer, and heat together is likely not a combination I'm going to test any time soon I think I'll stay away from methane for the same reason. Boomba! Boomba!
Other exotic gases might take less time or more time than air. It's kind of hard to predict. But the problem with any gas is that you'll have to fill the tire from time to time. Exotics are exotic because they are rare and difficult to isolate. Therefore they cost more. And the benefit is probably pretty low. Air and a pump are still pretty economical.
Now if you want to do something, design a better tube. Mylar is far less permeable than rubber. It'd hold gas for a very long time but it has no puncture resistance and no...zero...nada...zilch elasticity. Urethane was tried for a while and it works...sorta. It's not as elastic as rubber, it holds pressure slightly better, it has better puncture resistance than mylar but less - way less - than rubber, and it is a royal pain to patch...and costs around 5 times as much as rubber. Not a whole lot of plusses
__________________
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#54
Videre non videri
Thread Starter
Join Date: Sep 2004
Location: Gothenburg, Sweden
Posts: 3,208
Bikes: 1 road bike (simple, light), 1 TT bike (could be more aero, could be lighter), 1 all-weather commuter and winter bike, 1 Monark 828E ergometer indoor bike
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 4 Times
in
4 Posts
Ok, how about sulphur hexafluoride then?
Not for the WW crowd, though!
Not for the WW crowd, though!
#55
Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Posts: 27,362
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Mentioned: 152 Post(s)
Tagged: 1 Thread(s)
Quoted: 6219 Post(s)
Liked 4,218 Times
in
2,365 Posts
It'll make you voice real low But a cylinder of it cost around $800. Tad expensive (about $8/lb). Don't know what it'd do with rubber. And it is heavier than air...for those weight wienies
__________________
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#56
Senior Member
Military Aircraft use dry Nitrogen in their tires.
Nitrogen is a by-product of Oxygen. Oxygen is compressed and extracted at Air Bases for air-crews to breathe at high altitude.
Benefits of Dry Nitrogen include: No corrosion to wheels (oxidation is caused by oxygen), zero moisture means no condesation, and Nitrogen will not add oxygen to a fire, should the tire burn through.
Nitrogen is a by-product of Oxygen. Oxygen is compressed and extracted at Air Bases for air-crews to breathe at high altitude.
Benefits of Dry Nitrogen include: No corrosion to wheels (oxidation is caused by oxygen), zero moisture means no condesation, and Nitrogen will not add oxygen to a fire, should the tire burn through.
#57
Goggles & Doo-rag ready!
Join Date: Aug 2007
Location: Hampton Roads, VA
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Yes, argon would work. Argon molecular weight is ~40 and air has a MW of ~30. Argon is not diatomic like all other noble gases. The Argon would have no water vapor, much like dry nitrogen.
Based on the molecular weight difference, a bicycle tire filled with Argon would stay inflated ~25% longer than one using air. Mixing air with Argon would pose no problems should that be necessary. A schrader adapter would be needed since no industrial pressure regulators work with presta valves. Otherwise, Argon should work well. Good luck with that.
Edit: This post is retracted! Do not use Argon with Buna-N bicycle tire inner tubes!
Based on the molecular weight difference, a bicycle tire filled with Argon would stay inflated ~25% longer than one using air. Mixing air with Argon would pose no problems should that be necessary. A schrader adapter would be needed since no industrial pressure regulators work with presta valves. Otherwise, Argon should work well. Good luck with that.
Edit: This post is retracted! Do not use Argon with Buna-N bicycle tire inner tubes!
Last edited by Road_Biker; 08-23-07 at 06:55 AM.
#58
Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Posts: 27,362
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Mentioned: 152 Post(s)
Tagged: 1 Thread(s)
Quoted: 6219 Post(s)
Liked 4,218 Times
in
2,365 Posts
Military Aircraft use dry Nitrogen in their tires.
Nitrogen is a by-product of Oxygen. Oxygen is compressed and extracted at Air Bases for air-crews to breathe at high altitude.
Benefits of Dry Nitrogen include: No corrosion to wheels (oxidation is caused by oxygen), zero moisture means no condesation, and Nitrogen will not add oxygen to a fire, should the tire burn through.
Nitrogen is a by-product of Oxygen. Oxygen is compressed and extracted at Air Bases for air-crews to breathe at high altitude.
Benefits of Dry Nitrogen include: No corrosion to wheels (oxidation is caused by oxygen), zero moisture means no condesation, and Nitrogen will not add oxygen to a fire, should the tire burn through.
__________________
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#59
Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Posts: 27,362
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Mentioned: 152 Post(s)
Tagged: 1 Thread(s)
Quoted: 6219 Post(s)
Liked 4,218 Times
in
2,365 Posts
The noble gases are helium, neon, argon, krypton (no, not dangerous to Superman), xenon and radon. Xenon and radon are kind of dirty nobles however. Xenon like a nice tumble with the scullery maid every once in a while Xenon especially likes hanging around with those trollops, oxygen and fluorine. Radon is dirty and nasty enough that it will just fall apart all on it's own, shooting off a gamma ray here and there. It has been know to take a tumble with that **** fluorine too.
Based on the molecular weight difference, a bicycle tire filled with Argon would stay inflated ~25% longer than one using air. Mixing air with Argon would pose no problems should that be necessary. A schrader adapter would be needed since no industrial pressure regulators work with presta valves. Otherwise, Argon should work well. Good luck with that.
__________________
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#60
Elitist Troglodyte
Join Date: Jun 2006
Location: Dallas
Posts: 6,925
Bikes: 03 Raleigh Professional (steel)
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 2 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
I like the tutorial on the aristocratic (OCP?) gases.
__________________
Stupidity got us into this mess - why can't it get us out?
- Will Rogers
Stupidity got us into this mess - why can't it get us out?
- Will Rogers
#61
Mad bike riding scientist
Join Date: Nov 2004
Location: Denver, CO
Posts: 27,362
Bikes: Some silver ones, a red one, a black and orange one, and a few titanium ones
Mentioned: 152 Post(s)
Tagged: 1 Thread(s)
Quoted: 6219 Post(s)
Liked 4,218 Times
in
2,365 Posts
It's actually the other way around. Oxygen is 'made' during the process to isolate N2 from air. N2 is more important, economically, then O2. And, if you make liquid N2, O2 will condense in it. We don't leave open vessels of N2 about for that reason. You can concentrate O2 in it and go Boomba! Boomba!
__________________
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
Stuart Black
Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
#62
Yonkyu
Join Date: Oct 2005
Location: KTUS
Posts: 24
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
#63
Sir Fallalot
Join Date: Jul 2006
Posts: 5,286
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 13 Times
in
11 Posts
Sorry but nitrogen and oxygen are both elemental gases. That means that one can't be made from the other. Nitrogen and oxygen are distilled from air through some rather complex expansion/compression operations. As others have noted both here and in other posts on this topic, nitrogen doesn't add any benefit in bicycling. Just expense.
EDIT: like DMF said...
#65
Senior Member
I watched a Mythbusters once that experimented with filling footballs with helium to see if you could kick them farther. No dice, in such a small area it doesn't make any real difference, either in weight or in performance. Maybe for a poser though it would give them a "mental edge".
#66
Sir Fallalot
Join Date: Jul 2006
Posts: 5,286
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 13 Times
in
11 Posts
I watched a Mythbusters once that experimented with filling footballs with helium to see if you could kick them farther. No dice, in such a small area it doesn't make any real difference, either in weight or in performance. Maybe for a poser though it would give them a "mental edge".
BTW: it's "volume" the word you're looking for, not "area".
#67
Senior Member
Join Date: Aug 2003
Location: arlington, VA
Posts: 1,764
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 6 Post(s)
Likes: 0
Liked 5 Times
in
4 Posts
The raidus is just over 10 percent larger than oxygen and nitrogen, so you'd get a very MILD difusion benefit. It's a slightly heavier-so do you want to carry a couple of extra ounces around?
It's intert, so your tubes might dryrot a little slower.
Then again, nitrogen is almost as inert as a noble gas so you could get most of that same benefit without the expense of argon.
It's intert, so your tubes might dryrot a little slower.
Then again, nitrogen is almost as inert as a noble gas so you could get most of that same benefit without the expense of argon.
#68
Large Member
the atomic radius of argon (48 pm) is much smaller than the molecular radius of N2 and O2 (bond length 120 pm, atomic radius 74 pm), so it will leak out of a tyre much faster. the molecular or atomic mass has very little to do with its diffusion rate, it is almost all dependent on size. the mass will make it a little heavier in a tyre at the same pressure (argon and air have different densities at same pressure).
it is the diffusibility of a gas through rubber or latex that determines the rate of loss, not the solubility (since the diffusion loss is orders of magnitude higher than the evaporative loss of dissolved gas from the surface of the polymer). diffusion rate is proportional to size, so smaller molecules (or atoms) diffuse much faster. there is very little *********** due to electronic interactions with the tyre material, since both matrix and diffusing molecule are non-ionic, non-polar materials. the size/diffusion relationship is not linear, so smaller molecules diffuse much faster than larger molecules.
edit: i learn later that this helium part is wrong: we extract helium from natural gas, not by compression from the air. my bad.
Helium is not in danger of being depleted by our using it in balloons, etc. we extract it from the air, and it is all vented back to the atmosphere, so its a closed cycle. there is a small continuous loss of He from the earth by it being blown away from the upper atmosphere by solar wind, and simply by diffusion (it's not held very tightly by gravity), but this is nothing to do with our industrial processes using He.
it is the diffusibility of a gas through rubber or latex that determines the rate of loss, not the solubility (since the diffusion loss is orders of magnitude higher than the evaporative loss of dissolved gas from the surface of the polymer). diffusion rate is proportional to size, so smaller molecules (or atoms) diffuse much faster. there is very little *********** due to electronic interactions with the tyre material, since both matrix and diffusing molecule are non-ionic, non-polar materials. the size/diffusion relationship is not linear, so smaller molecules diffuse much faster than larger molecules.
edit: i learn later that this helium part is wrong: we extract helium from natural gas, not by compression from the air. my bad.
Helium is not in danger of being depleted by our using it in balloons, etc. we extract it from the air, and it is all vented back to the atmosphere, so its a closed cycle. there is a small continuous loss of He from the earth by it being blown away from the upper atmosphere by solar wind, and simply by diffusion (it's not held very tightly by gravity), but this is nothing to do with our industrial processes using He.
Last edited by urodacus; 08-23-07 at 05:14 AM.
#69
Junkmaster
Join Date: Aug 2007
Location: Federal Way, WA
Posts: 155
Bikes: Lemond '05 Alpe d'Huez, Rebuilt in 2020
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Can you refer me to any publications or online literature for the diffusion characteristics of CO2?
Because right now I tend to believe that the molecular size determines the diffusive characteristics of a gas rather than its solubility in solids - this abstract's last sentence seems to imply that concentration has a relatively small influence on diffusion - the classic pressure gradient, temperature, etc. factors appear to be more important for carbon dioxide diffusion rather than chemical solubility (influenced by concentration). Although CO2 is well known to dissolve in water, however. I'm not sure how it would do in polymers.
I've always thought CO2 was used for those quick-fill canisters b/c it had good diffusion characteristics.
Here we also see that the diffusion coefficient for CO2 is lower than O2, which itself is lower than H2O - almost completely hierarchical on size.
Last edited by facial; 08-23-07 at 02:32 AM.
#70
Sir Fallalot
Join Date: Jul 2006
Posts: 5,286
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 13 Times
in
11 Posts
Here we also see that the diffusion coefficient for CO2 is lower than O2, which itself is lower than H2O - almost completely hierarchical on size.
BTW. CO2 will seep through tubes quicker than "normal air".
Last edited by wroomwroomoops; 08-23-07 at 04:07 AM.
#71
Senior Member
Join Date: Aug 2006
Location: Auckland, New Zealand
Posts: 51
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 1 Post(s)
Likes: 0
Liked 1 Time
in
1 Post
Helium is not in danger of being depleted by our using it in balloons, etc. we extract it from the air, and it is all vented back to the atmosphere, so its a closed cycle. there is a small continuous loss of He from the earth by it being blown away from the upper atmosphere by solar wind, and simply by diffusion (it's not held very tightly by gravity), but this is nothing to do with our industrial processes using He.
#72
Large Member
#73
Sir Fallalot
Join Date: Jul 2006
Posts: 5,286
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 13 Times
in
11 Posts
Ever tried sucking up a helium-filled balloon, and then talking? Is mucho fun. I must admit, I am culpable of releasing into the atmosphere a couple of liters of helium for the purpose of sheer jakassery.
#74
Goggles & Doo-rag ready!
Join Date: Aug 2007
Location: Hampton Roads, VA
Posts: 48
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
FWIW, this article describes the process of permeation related to vacuum quality. https://www.vacuumlab.com/Articles/VacLab30.pdf
This reference describes the viscous and molecular leakage constants for gases relative to helium:
https://www.lacotech.com/products/997...eaktechref.pdf
In the Lacotech document, Argon constants are slightly less than those for nitrogen or air and thus Argon molecular leaks would be at slightly lower rates than for nitrogen or air. However, Argon would need to be tested with Buna-N material for any meaningful bicycle tire permeation data.
Edit: Based on Buna-N compability with Argon from this elastomer manufacturer:
https://www.ind-ex.biz/catalog_images/IndexCatalog.pdf,
Argon has poor compability with Buna-N, Nitrile, and NRBT rubber. A Buna-N tire inner tube will fail prematurely when used with Argon!
As such, I retract my previous post and warn against using Argon in bicycle tires!
This reference describes the viscous and molecular leakage constants for gases relative to helium:
https://www.lacotech.com/products/997...eaktechref.pdf
In the Lacotech document, Argon constants are slightly less than those for nitrogen or air and thus Argon molecular leaks would be at slightly lower rates than for nitrogen or air. However, Argon would need to be tested with Buna-N material for any meaningful bicycle tire permeation data.
Edit: Based on Buna-N compability with Argon from this elastomer manufacturer:
https://www.ind-ex.biz/catalog_images/IndexCatalog.pdf,
Argon has poor compability with Buna-N, Nitrile, and NRBT rubber. A Buna-N tire inner tube will fail prematurely when used with Argon!
As such, I retract my previous post and warn against using Argon in bicycle tires!
Last edited by Road_Biker; 08-23-07 at 06:59 AM.
#75
Sir Fallalot
Join Date: Jul 2006
Posts: 5,286
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 9 Post(s)
Likes: 0
Liked 13 Times
in
11 Posts
Edit: Based on Buna-N compability with Argon from this elastomer manufacturer:
https://www.ind-ex.biz/catalog_images/IndexCatalog.pdf,
Argon has poor compability with Buna-N, Nitrile, and NRBT rubber. A Buna-N tire inner tube will fail prematurely when used with Argon!
As such, I retract my previous post and warn against using Argon in bicycle tires!
https://www.ind-ex.biz/catalog_images/IndexCatalog.pdf,
Argon has poor compability with Buna-N, Nitrile, and NRBT rubber. A Buna-N tire inner tube will fail prematurely when used with Argon!
As such, I retract my previous post and warn against using Argon in bicycle tires!