Superb video on nitrogen vs air
- Thread starter George Bynum
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I have a Nitrogen generator that I've been using for 12 years now. It makes a difference, but not for what some people charge. I put it in every tire I install for free, and all my tires too. Although the benefits are small, it makes a lot more sense than putting water filled air into a tire. Would you want your nitrogen charged shocks, and lift cylinders fill with wet air instead? No matter how you slice it, nitrogen will always trump plain old wet air.
Checking my N2, it is zero% humidity, with a dew point of -58 degrees, with 4% O2. Much better than what you can get anywhere else with free air.
Checking my N2, it is zero% humidity, with a dew point of -58 degrees, with 4% O2. Much better than what you can get anywhere else with free air.
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Originally Posted By: sdowney717
Why not use CO2 gas for filling tires. Bigger molecules leak less, and it will not burn.
http://www.pirate4x4.com/forum/jeep-non-hardcore/404037-nitrogen-vs-co2-tires.html
CO2 may be a larger molecule and so permeability is slower, but it is much more soluable in rubber and so will leak out very quickly. For instance, if you've ever used one of those CO2 cartridges to rapidly inflate your bicycle tire after a flat, you'll find you lose probably 10% of the pressure within an hour or two.
Here's an old, old posting by a chemistry professor on this subject:
http://www.madsci.org/posts/archives/1998-05/895552329.Ch.r.html
Why not use CO2 gas for filling tires. Bigger molecules leak less, and it will not burn.
http://www.pirate4x4.com/forum/jeep-non-hardcore/404037-nitrogen-vs-co2-tires.html
CO2 may be a larger molecule and so permeability is slower, but it is much more soluable in rubber and so will leak out very quickly. For instance, if you've ever used one of those CO2 cartridges to rapidly inflate your bicycle tire after a flat, you'll find you lose probably 10% of the pressure within an hour or two.
Here's an old, old posting by a chemistry professor on this subject:
http://www.madsci.org/posts/archives/1998-05/895552329.Ch.r.html
Originally Posted By: Sayjac
I'll stick with the free 78% variety and check tire pressure occasionally, same as I've always done. Those that choose to pay for the extra ?%N, have at it.
Same here. Messin' with tires around here means too many. We simply have a little gizmo on the shop compressor that removes the majority of the water. 78% seems to work just fine...
I'll stick with the free 78% variety and check tire pressure occasionally, same as I've always done. Those that choose to pay for the extra ?%N, have at it.
Same here. Messin' with tires around here means too many. We simply have a little gizmo on the shop compressor that removes the majority of the water. 78% seems to work just fine...
4WD
$50 site donor 2025
Hope it is stored properly - N2 is considered safe but can cause oxygen deprivation if it displaces air. We require oxygen monitors and alarms in rooms having membrane units etc ...
Originally Posted By: Astro14
Originally Posted By: Nate1979
I found this reference interesting. The link is to a pdf report on the permeation difference between O2 and N2. According to the report:
Quote:
O2 "permeates" approximately 3-4 times faster than does N2 through a typical rubber, as is used in tires, primarily
because O2 has a slightly smaller effective molecular size than does N2.
Details here:
http://www.getnitrogen.org/pdf/graham.pdf
I would be interesting for those who understand the math to check the report.
It's not a math question...it's a source question.
You're quoting a nitrogen seller on why you should use nitrogen.
Yes, the math is correct as far as it goes. The source being pro nitrogen, leaves out the fact that gases equalize partial pressures across a permeable membrane. If oxygen can leak out, it can leak in. Oxygen will enter the tire through the rubber until the partial pressure of oxygen inside the tire equals the partial pressure outside the tire.
They won't tell you that your wonderful "pure" nitrogen fill doesn't stay pure. That evil oxygen that they have gotten rid of for you is more than happy to leak back in.
Ed
Originally Posted By: Nate1979
I found this reference interesting. The link is to a pdf report on the permeation difference between O2 and N2. According to the report:
Quote:
O2 "permeates" approximately 3-4 times faster than does N2 through a typical rubber, as is used in tires, primarily
because O2 has a slightly smaller effective molecular size than does N2.
Details here:
http://www.getnitrogen.org/pdf/graham.pdf
I would be interesting for those who understand the math to check the report.
It's not a math question...it's a source question.
You're quoting a nitrogen seller on why you should use nitrogen.
Yes, the math is correct as far as it goes. The source being pro nitrogen, leaves out the fact that gases equalize partial pressures across a permeable membrane. If oxygen can leak out, it can leak in. Oxygen will enter the tire through the rubber until the partial pressure of oxygen inside the tire equals the partial pressure outside the tire.
They won't tell you that your wonderful "pure" nitrogen fill doesn't stay pure. That evil oxygen that they have gotten rid of for you is more than happy to leak back in.
Ed
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Kestas
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Originally Posted By: Traction
I have a Nitrogen generator that I've been using for 12 years now. It makes a difference, but not for what some people charge. I put it in every tire I install for free, and all my tires too. Although the benefits are small, it makes a lot more sense than putting water filled air into a tire. Would you want your nitrogen charged shocks, and lift cylinders fill with wet air instead? No matter how you slice it, nitrogen will always trump plain old wet air.
Checking my N2, it is zero% humidity, with a dew point of -58 degrees, with 4% O2. Much better than what you can get anywhere else with free air.
Do you use a water based lube to mount the tires? How do you keep it out of the tire cavity?
I have a Nitrogen generator that I've been using for 12 years now. It makes a difference, but not for what some people charge. I put it in every tire I install for free, and all my tires too. Although the benefits are small, it makes a lot more sense than putting water filled air into a tire. Would you want your nitrogen charged shocks, and lift cylinders fill with wet air instead? No matter how you slice it, nitrogen will always trump plain old wet air.
Checking my N2, it is zero% humidity, with a dew point of -58 degrees, with 4% O2. Much better than what you can get anywhere else with free air.
Do you use a water based lube to mount the tires? How do you keep it out of the tire cavity?
From getnitrogen.org:
"The pressure in nitrogen filled tires will change when the temperature changes, just as it does with air filled tires, because nitrogen and oxygen respond to changes in ambient temperature in a similar manner."
Like, for every 10 F change in ambient temperature, there's about a 1 psi change in pressure in your tires.
Anyone think he's detected a loss of pressure from leakage that's anywhere near that?
"The pressure in nitrogen filled tires will change when the temperature changes, just as it does with air filled tires, because nitrogen and oxygen respond to changes in ambient temperature in a similar manner."
Like, for every 10 F change in ambient temperature, there's about a 1 psi change in pressure in your tires.
Anyone think he's detected a loss of pressure from leakage that's anywhere near that?
I've had this stray thought floating around in my head for a while, so I'm going to put it down on paper (and by *paper* I mean electrons!), and let people take pot shots at it. Here's the premise.
This business about air containing water is a bunch of hooey! At least it is when it comes to explaining why nitrogen inflation is better then air! Water vapor (steam) behaves like an ideal gas (PV = nRT), just like all the other gases do - at the temperatures and pressures we are dealing with when we discuss tires.
Further, there is the partial pressure of gases law that states that you can treat gases like their individual components. So a tire filled with 100% nitrogen will gradually accumulate oxygen because the partial pressure of oxygen in the atmosphere is greater than partial pressure of the oxygen inside the tire. The same is true for water vapor.
The partial pressure of the water vapor inside a freshly air filled tire is greater than the outside air, so the water tries to migrate out - even when the air line is spitting out water and even when people use water based lubes to mount the tire.
Proof? Has any ever seen puddles of water inside on freshly demounted tire? You'd think that would be a common sight if water was the such a significant issue in the nitrogen vs air debate.
So take your best shot at this argument!! Let's see if it stands up to scrutiny.
This business about air containing water is a bunch of hooey! At least it is when it comes to explaining why nitrogen inflation is better then air! Water vapor (steam) behaves like an ideal gas (PV = nRT), just like all the other gases do - at the temperatures and pressures we are dealing with when we discuss tires.
Further, there is the partial pressure of gases law that states that you can treat gases like their individual components. So a tire filled with 100% nitrogen will gradually accumulate oxygen because the partial pressure of oxygen in the atmosphere is greater than partial pressure of the oxygen inside the tire. The same is true for water vapor.
The partial pressure of the water vapor inside a freshly air filled tire is greater than the outside air, so the water tries to migrate out - even when the air line is spitting out water and even when people use water based lubes to mount the tire.
Proof? Has any ever seen puddles of water inside on freshly demounted tire? You'd think that would be a common sight if water was the such a significant issue in the nitrogen vs air debate.
So take your best shot at this argument!! Let's see if it stands up to scrutiny.
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Originally Posted By: CapriRacer
I've had this stray thought floating around in my head for a while, so I'm going to put it down on paper (and by *paper* I mean electrons!), and let people take pot shots at it. Here's the premise.
This business about air containing water is a bunch of hooey! At least it is when it comes to explaining why nitrogen inflation is better then air! Water vapor (steam) behaves like an ideal gas (PV = nRT), just like all the other gases do - at the temperatures and pressures we are dealing with when we discuss tires.
Further, there is the partial pressure of gases law that states that you can treat gases like their individual components. So a tire filled with 100% nitrogen will gradually accumulate oxygen because the partial pressure of oxygen in the atmosphere is greater than partial pressure of the oxygen inside the tire. The same is true for water vapor.
The partial pressure of the water vapor inside a freshly air filled tire is greater than the outside air, so the water tries to migrate out - even when the air line is spitting out water and even when people use water based lubes to mount the tire.
Proof? Has any ever seen puddles of water inside on freshly demounted tire? You'd think that would be a common sight if water was the such a significant issue in the nitrogen vs air debate.
So take your best shot at this argument!! Let's see if it stands up to scrutiny.
Well, I have seen water in tires many times, mostly in the winter, and usually from someone topping off slow leaking tires all the time. So, yes the water, and oxygen can eventually equalize, but it takes a lot longer when adding fresh oxygen and water into the tire. The oxygen in a tire might get down to partial pressure someday, that I think is around 5%, but every time you add fresh air it goes back up, and the moisture too. With 95% nitrogen it has already equalized, and will stay lower by adding N2, instead of using fresh wet air on fill ups. Even on my air compressor I have a refrigerated dryer, which most people don't have, so that's not so bad. But, I ask the opposite question of, how can wet compressed air possibly be better than N2 if both are free?
I checked the O2 level on my trailer tires that have stayed outside untouched for 4 years and they were at 5%.
I've had this stray thought floating around in my head for a while, so I'm going to put it down on paper (and by *paper* I mean electrons!), and let people take pot shots at it. Here's the premise.
This business about air containing water is a bunch of hooey! At least it is when it comes to explaining why nitrogen inflation is better then air! Water vapor (steam) behaves like an ideal gas (PV = nRT), just like all the other gases do - at the temperatures and pressures we are dealing with when we discuss tires.
Further, there is the partial pressure of gases law that states that you can treat gases like their individual components. So a tire filled with 100% nitrogen will gradually accumulate oxygen because the partial pressure of oxygen in the atmosphere is greater than partial pressure of the oxygen inside the tire. The same is true for water vapor.
The partial pressure of the water vapor inside a freshly air filled tire is greater than the outside air, so the water tries to migrate out - even when the air line is spitting out water and even when people use water based lubes to mount the tire.
Proof? Has any ever seen puddles of water inside on freshly demounted tire? You'd think that would be a common sight if water was the such a significant issue in the nitrogen vs air debate.
So take your best shot at this argument!! Let's see if it stands up to scrutiny.
Well, I have seen water in tires many times, mostly in the winter, and usually from someone topping off slow leaking tires all the time. So, yes the water, and oxygen can eventually equalize, but it takes a lot longer when adding fresh oxygen and water into the tire. The oxygen in a tire might get down to partial pressure someday, that I think is around 5%, but every time you add fresh air it goes back up, and the moisture too. With 95% nitrogen it has already equalized, and will stay lower by adding N2, instead of using fresh wet air on fill ups. Even on my air compressor I have a refrigerated dryer, which most people don't have, so that's not so bad. But, I ask the opposite question of, how can wet compressed air possibly be better than N2 if both are free?
I checked the O2 level on my trailer tires that have stayed outside untouched for 4 years and they were at 5%.
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Originally Posted By: Traction
I checked the O2 level on my trailer tires that have stayed outside untouched for 4 years and they were at 5%.
I remember a high school chemistry experiment using rust creation to identify O2 ratio ... curious how you do it?
I checked the O2 level on my trailer tires that have stayed outside untouched for 4 years and they were at 5%.
I remember a high school chemistry experiment using rust creation to identify O2 ratio ... curious how you do it?
Originally Posted By: George Bynum
Originally Posted By: Traction
I checked the O2 level on my trailer tires that have stayed outside untouched for 4 years and they were at 5%.
I remember a high school chemistry experiment using rust creation to identify O2 ratio ... curious how you do it?
I have a digital O2 gauge they use to test SCUBA tanks, but now I see it needs a new $110 sensor
I also have a psycrometer that measures temp, humidity, and dew point. Just check a tire sitting for a couple years, and the humidity was 16% with a dew point of 15 degrees.
Originally Posted By: Traction
I checked the O2 level on my trailer tires that have stayed outside untouched for 4 years and they were at 5%.
I remember a high school chemistry experiment using rust creation to identify O2 ratio ... curious how you do it?
I have a digital O2 gauge they use to test SCUBA tanks, but now I see it needs a new $110 sensor
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Originally Posted By: CapriRacer
I've had this stray thought floating around in my head for a while, so I'm going to put it down on paper (and by *paper* I mean electrons!), and let people take pot shots at it. Here's the premise.
This business about air containing water is a bunch of hooey! At least it is when it comes to explaining why nitrogen inflation is better then air! Water vapor (steam) behaves like an ideal gas (PV = nRT), just like all the other gases do - at the temperatures and pressures we are dealing with when we discuss tires.
Further, there is the partial pressure of gases law that states that you can treat gases like their individual components. So a tire filled with 100% nitrogen will gradually accumulate oxygen because the partial pressure of oxygen in the atmosphere is greater than partial pressure of the oxygen inside the tire. The same is true for water vapor.
The partial pressure of the water vapor inside a freshly air filled tire is greater than the outside air, so the water tries to migrate out - even when the air line is spitting out water and even when people use water based lubes to mount the tire.
Proof? Has any ever seen puddles of water inside on freshly demounted tire? You'd think that would be a common sight if water was the such a significant issue in the nitrogen vs air debate.
So take your best shot at this argument!! Let's see if it stands up to scrutiny.
OK, I'll take a stab at this one, and if you think I'm wrong, please speak up, contrary to current wisdom, I DON'T know it all.
You are correct on the law of partial pressures, ... to an extent.
First, the law of partial pressures only applies to gases within a common container, ie. atmosphere, a tire, a tank, whatever.
When you fill a tire with two constituents ie water vapor and O2, you do have two pressures WITHIN the tire, forming a total pressure, ie 35psi. Now lets fill that tire with 100% N2, single pressure 35psi.
Outside, you have air, with all it's partial pressures adding up to 0psi (gauge)
If you want to get complicated and use absolute pressure, then the tire has 49.7psi and the air is 14.7psi, but that's just unneeded complication.
No matter what the constituents of either container are, as long as it will hold pressure, then there can be no migration of the lower pressure to the higher pressure. Air can't infiltrate the tire when it's pressure is higher. In that instance total pressure is what matters.
Just as heat will migrate to cold, higher pressure will migrate to lower pressure. No migration of air can enter the tire until the atmospheric pressure is greater than the pressure inside the tire, no matter what the makeup of the gases involved.
I've had this stray thought floating around in my head for a while, so I'm going to put it down on paper (and by *paper* I mean electrons!), and let people take pot shots at it. Here's the premise.
This business about air containing water is a bunch of hooey! At least it is when it comes to explaining why nitrogen inflation is better then air! Water vapor (steam) behaves like an ideal gas (PV = nRT), just like all the other gases do - at the temperatures and pressures we are dealing with when we discuss tires.
Further, there is the partial pressure of gases law that states that you can treat gases like their individual components. So a tire filled with 100% nitrogen will gradually accumulate oxygen because the partial pressure of oxygen in the atmosphere is greater than partial pressure of the oxygen inside the tire. The same is true for water vapor.
The partial pressure of the water vapor inside a freshly air filled tire is greater than the outside air, so the water tries to migrate out - even when the air line is spitting out water and even when people use water based lubes to mount the tire.
Proof? Has any ever seen puddles of water inside on freshly demounted tire? You'd think that would be a common sight if water was the such a significant issue in the nitrogen vs air debate.
So take your best shot at this argument!! Let's see if it stands up to scrutiny.
OK, I'll take a stab at this one, and if you think I'm wrong, please speak up, contrary to current wisdom, I DON'T know it all.
You are correct on the law of partial pressures, ... to an extent.
First, the law of partial pressures only applies to gases within a common container, ie. atmosphere, a tire, a tank, whatever.
When you fill a tire with two constituents ie water vapor and O2, you do have two pressures WITHIN the tire, forming a total pressure, ie 35psi. Now lets fill that tire with 100% N2, single pressure 35psi.
Outside, you have air, with all it's partial pressures adding up to 0psi (gauge)
If you want to get complicated and use absolute pressure, then the tire has 49.7psi and the air is 14.7psi, but that's just unneeded complication.
No matter what the constituents of either container are, as long as it will hold pressure, then there can be no migration of the lower pressure to the higher pressure. Air can't infiltrate the tire when it's pressure is higher. In that instance total pressure is what matters.
Just as heat will migrate to cold, higher pressure will migrate to lower pressure. No migration of air can enter the tire until the atmospheric pressure is greater than the pressure inside the tire, no matter what the makeup of the gases involved.
We're not talking about pressure migrating in/out - its about molecules.
The whole premise is that N2 is "larger" and less likely to "leak" out.
I'll still take my free 78% N2 fills. With a bike pump that inputs whatever the RH is at the moment.
The whole premise is that N2 is "larger" and less likely to "leak" out.
I'll still take my free 78% N2 fills. With a bike pump that inputs whatever the RH is at the moment.
Originally Posted By: bchannell
OK, I'll take a stab at this one, and if you think I'm wrong, please speak up, contrary to current wisdom, I DON'T know it all. ......
Good to know.
Originally Posted By: bchannell
...... No matter what the constituents of either container are, as long as it will hold pressure, then there can be no migration of the lower pressure to the higher pressure. Air can't infiltrate the tire when it's pressure is higher. In that instance total pressure is what matters. ....
Sorry, but that isn't the way it works - and it has been demonstrated.
I can not remember how long ago it was, but a colleague of mine repeatedly filled a tire with N2, then deflated it, coming to the point where there was very little N2 (percentage wise) in the tire. He then put in an O2 monitor and recorded the rise in O2 percentage over time. He presented this at a tire conference and I didn't get a copy of the paper. Basically he proved the Partial Pressure of Gases Law works everywhere.
OK, I'll take a stab at this one, and if you think I'm wrong, please speak up, contrary to current wisdom, I DON'T know it all. ......
Good to know.
Originally Posted By: bchannell
...... No matter what the constituents of either container are, as long as it will hold pressure, then there can be no migration of the lower pressure to the higher pressure. Air can't infiltrate the tire when it's pressure is higher. In that instance total pressure is what matters. ....
Sorry, but that isn't the way it works - and it has been demonstrated.
I can not remember how long ago it was, but a colleague of mine repeatedly filled a tire with N2, then deflated it, coming to the point where there was very little N2 (percentage wise) in the tire. He then put in an O2 monitor and recorded the rise in O2 percentage over time. He presented this at a tire conference and I didn't get a copy of the paper. Basically he proved the Partial Pressure of Gases Law works everywhere.
Originally Posted By: CapriRacer
... I can not remember how long ago it was, but a colleague of mine repeatedly filled a tire with N2, then deflated it, coming to the point where there was very little N2 (percentage wise) in the tire. ...
?? Didn't you mean to say " ... to the point where there was very little O2 (percentage wise) ... "? If so, I agree completely; very good post otherwise!
... I can not remember how long ago it was, but a colleague of mine repeatedly filled a tire with N2, then deflated it, coming to the point where there was very little N2 (percentage wise) in the tire. ...
?? Didn't you mean to say " ... to the point where there was very little O2 (percentage wise) ... "? If so, I agree completely; very good post otherwise!
We started doing nitrogen tire fills at my work. Obviously it is not free and all the techs have made names making fun of it. Probably doesn't help that it came from the Moc snake oil peddler. The machine we have is pretty cool at least. Hook up hoses to the valve stems, pick a pressure, hit a button, and walk back 20 minutes later.
Originally Posted By: CR94
Originally Posted By: CapriRacer
... I can not remember how long ago it was, but a colleague of mine repeatedly filled a tire with N2, then deflated it, coming to the point where there was very little N2 (percentage wise) in the tire. ...
?? Didn't you mean to say " ... to the point where there was very little O2 (percentage wise) ... "? If so, I agree completely; very good post otherwise!
Right you are.
Originally Posted By: CapriRacer
... I can not remember how long ago it was, but a colleague of mine repeatedly filled a tire with N2, then deflated it, coming to the point where there was very little N2 (percentage wise) in the tire. ...
?? Didn't you mean to say " ... to the point where there was very little O2 (percentage wise) ... "? If so, I agree completely; very good post otherwise!
Right you are.
edyvw
$50 site donor 2025
When Costco fill Nitrogen in my tires I can feel at least 50hp more and for sure 30-40lb/ft.
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