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Nitrogen in tires?

panteradougpanteradougMember
Need someone experienced here on this subject.

With magnesium Campagnolos is there a chemical issue with using nitrogen in the tires?

To be effective, the tire needs to be at least 85% filled with nitrogen.

With only one valve stem, how do you drain the tire of air and replace it with nitrogen?

Obviously there is only one way to do it, I think (that's why I'm asking).

Is it worth the effort?

I'm going to have to "rent" a tank of nitrogen from the gas supplier. I presume the welding suppliers will have it?

Anyone here done this or have opinions on it's worthwhileness?
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joulesjoules"Racing is Life, anything before or after is just waiting" - Steve McQueen
The air you breathe (and currently in your tires) is 79% nitrogen anyway. IMO going full nitrogen is a waste of time and money, unless you are running in a top competition class and even then it's debatable.

When your tire is down a few pounds later, how are you going to top off?

Julian
goodrocgoodrocMember
Joules, you just beat me by a minute. Yes you just remove the Oxygen and replace that with more (20%) Nitrogen. But the benefit is also that it is completely dry as where if you use compressed air there is usually some moisture in it. Thats why they use pure Nitrogen in Aircraft Tires. If you want a bottle for the track day just get an old Scuba diving tank or talk to your local Fire Brigade (3000psi of compressed air) and it should be good for hundreds of Tires and will be much cheaper than a Nitrogen tank I suppose ;-)
C comp2Member
quote:
Originally posted by goodroc:
Joules, you just beat me by a minute. Yes you just remove the Oxygen and replace that with more (20%) Nitrogen. But the benefit is also that it is completely dry as where if you use compressed air there is usually some moisture in it. Thats why they use pure Nitrogen in Aircraft Tires. If you want a bottle for the track day just get an old Scuba diving tank or talk to your local Fire Brigade (3000psi of compressed air) and it should be good for hundreds of Tires and will be much cheaper than a Nitrogen tank I suppose ;-)


We use high pressure banks oxygen and our nitrogen tank outlast an entire bank of oxygen tanks. Oxygen bleeds down a lot quicker then a gas that can be taken to liquid.

With Nitrogen you will hold the pressure to the very end.

I think a scuba tank would probably do good but certainly not 100's of tires. If you have to have either filled then there is little difference there.

Of course working with what you have is often everything. We see nitrogen tanks pop up on local auctions for very little money routinely.




jfb05177jfb05177Member
would I want N2? YES
would I pay the amount I've heard (>$100) NO!!!

While O2 is considered deterimental since I casues oxidation and leaks slighty quicker, to me the thing I would most want to eleminate would be water. now to figure out a way to reduce the water from humid air that enters when mounting, maybe use a heat gun

I was googling for a clip in line air dyrer filter (the filter alone is less than $20). which I think I will make up something for my use. I found they now have personal N2 generators for sale. the Parker TyreSaver wand attaches to end of a standard air house, has a dyrer and an oxegen scrubber. the cost is only $1000 with replacement filter/scrubber cartridge about $600
panterrorpanterrorMy 74 GTS
quote:
Originally posted by comp2: Oxygen bleeds down a lot quicker then a gas that can be taken to liquid.


They both liquefy. Nitrogen boils at 77K (Kelvin) and Oxygen at 90K, meaning O2 liquefies at a little higher temp than Nitrogen. They are both pretty close in molecular weight O2=32 gm/gm-mole and N2=28 gm/gm-mole so a liter of liquid O2 would convert nearly as much gas as a liter of liquid N2.



That’s one heck of a bank of gas cylinders Gary.

The most significant benefit of using pure N2 is both the absence of water and oxygen. As mentioned in the thread, most aircraft wheels were magnesium and magnesium oxidizes rapidly in the presence of O2 and water so the use of N2 prevents corrosion because it is chemically much less reactive than oxygen and water completes the circuit, especially if there are dissimilar metals present (galvanic corrosion). Pantera Campys are of course mag as well.

Eliminating any water vapor should make the tire pressure a little more stable over a given temperature range. At altitude in an aircraft tire, H2O vapor will freeze and no longer contribute to tire pressure at all. The presence of H20 vapor will also make tire pressures raise more in racing situations as tire temperatures increase. Fill your tire on a hot humid day with one of those cheepo gas station outdoor compressors you pump with quarters and you will have liquid water in your tires at Winter temperatures.

You don’t have to have N2 to eliminate water. Just a good inline desiccant cartridge will do almost as well and achieve pressure dew points of <=100F and this will probably eliminate the lion’s share of corrosive activity.
In theory pure O2 would diffuse (leak) out more slowly and hold tire pressure better than pure N2 because diffusion rate is inversely proportional to the square root of density (proportional to molar mass). In other words, big molecules diffuse more slowly. But O2 and N2 are so close in molecular weight this isn’t an appreciable effect and air is in between the two so even less difference compared to air.

Other than preventing long term corrosion in mag wheels I think it’s picking the fly sh!t out of the pepper for street cars. Just buy an inline desiccant cartridge for your compressed air line and call it a day Doug.

The claims about N2 making tires last longer are usually over blown. I know, the truck stops put N2 in the over the road truck tires but they recap those things and they cost a bundle so prolonging a tire is more significant. Ozone and Ultra Violet light are the chief culprits in degrading tire rubber. You can get rid of ozone on the interior but it will still be there along with UV on the outside.

For estimating how many tire fills you can get from a compressed air tank, the volume of gas is proportional to absolute pressure. For every atmosphere of pressure (14.7 psi) increase, the volume of gas in the tank goes up x1. Most scuba tanks are referred to by how much gas they hold at rated pressure. Anywhere from 65-120 cubic feet is typical and pressures up to 3000 psi depending upon tank type. 315/35/17 is a popular Pantera tire. They’re about 2 cubic feet internal volume. So to raise pressure from completely flat (1 atm absolute) tire to 30 psi (about 2 ATMs) would take 4 cubic feet out of the scuba tank. So even the smallest scuba tank would likely fill 15 large rear tires from completely flat and would top up a partially full tire a very large number times. This assumes ideal gas behavior but close enough.

Be advised, there is a significant danger in using high pressure gas source to fill tires. As a precaution, you should have a very good regulator, an orifice to limit flow, and a very reliable relief valve on the low pressure (tire) side. Being in close proximity to an exploding tire/wheel can easily kill you.

You also won’t find an industrial gas company willing to put pure N2 into a scuba tank or another tank meant for breathing air for concern it would be stored and/or change hands and someone would assume it is full of air instead of N2 and….well, die. Take the scuba tank out of service, paint it, and identify it as not for breathing air. You will also discover the fittings on scuba (air) tanks, oxygen and nitrogen tanks conform to Compressed Gas Association standards and are all different to discourage filling them with the wrong gas. You will need to make your own conversion charging line to do so but just be careful you don’t nominate yourself for Darwin awards in the course of doing so.

Best,
K
panteradougpanteradougMember
Kelly. As long as you are in the calculating mood, how contaminated is the nitrogen going to be by the air left in the tire when drained as completely as you can get it? Then pumping it up with nitrogen?

I'm taking a guess and thinking around 5% contaminated with air?

That means no matter what I do there will still be a percentage of water vapor trapped in the tire?

Is the tank of nitrogen going to be 100% free of water vapor because nitrogen retains no water vapor or just because of the manor the tank was filled with nitrogen?

The descant filter is a good idea though. Never thought to look for one? Doe!
panterrorpanterrorMy 74 GTS
quote:
Originally posted by PanteraDoug:Kelly. As long as you are in the calculating mood, how contaminated is the nitrogen going to be by the air left in the tire when drained as completely as you can get it? Then pumping it up with nitrogen?...I'm taking a guess and thinking around 5% contaminated with air?


Pretty close depending upon what pressure you fill to. In round numbers air is 78% N2, 21%O2 and 1% Argon (there is actually trace amounts of lots of stuff but close enough). It’s not exactly right, and hopefully Avogadro (Google that one for grins Doug) will forgive me, but as an approximation, in my example of the 335/35/17 that was about 2 cubic feet internal volume, if it’s completely flat at atmospheric pressure, there’s still about 0.42 ft3 of oxygen in there by volume. If you fill it to 29.4 psi (2 ATMs gauge), there will be 6 ft3 of gas and still 0.42ft3 of oxygen so by volume it’s now 7%. Every time you drain and refill the tire to 2 ATMs you dilute the oxygen to about a third of the previous concentration. The size of the tire doesn’t matter for this estimation but if you fill it to a higher pressure, say 45 psig (3ATM gauge), it dilutes to about ¼ the concentration each successive fill. Kapeesh?

quote:
Is the tank of nitrogen going to be 100% free of water vapor because nitrogen retains no water vapor or just because of the manor the tank was filled with nitrogen?


It's a byproduct of how the industrial gas companies produce the gas. They super-chill and liquefy air, then put it in a distillation column where it stratifies in the column in order of molecular weight. Since N2 doesn’t liquefy until about -320F (and you thought it was cold outside tonight!), water just becomes another solid contaminate that gets removed with CO2 and a bunch of other BS. When they convert the liquid N2 back to gas, it’s pretty much just N2.

quote:
That means no matter what I do there will still be a percentage of water vapor trapped in the tire?


Yah, but its presence gets diluted just like the oxygen if you fill and drain repeatedly with N2.

quote:
The descant filter is a good idea though. Never thought to look for one? Doe!


McMaster Carr is your friend

Best,
K
panterrorpanterrorMy 74 GTS
quote:
Originally posted by JFB #05177:
While industrail N2 should be dry due to the seperation process, however I noticed the garages around here have a scrubber system, so wouldn't you expect their n2 to be only as dry as there descant?


Depends upon the source of their N2 and the condition of their dessicant. If it's a saturated dessicant cartrdige it may actaully give up H20 to the N2 but only if it is well beyond its service life. There are other air separation processes used for low grade tire N2 such as semi-permeable membrane and pressure swing adsorption but they all are pretty darn good dessicating processes too. If the N2 came out of a high pressure cylinder its almost certain the gas was produced by liquifaction and is very dry....<<<100F pressure dew point.

K
goodrocgoodrocMember
And just for the Record: I wasn't encouraging anyone to fill Scuba tanks with N2 but merely use the standard filtered and dry air that any Diving Centers Compressor system delivers as a cheaper substitute than the N2 for the discussed Track-day usage. I apologize if that could be misunderstood. Secondly as correctly mentioned extreme precautions should be taken when using a source of high pressure. If you live close to an Airstrip it might be worth to pay them a visit. The Engineers there may be able to help you with some N2 if you insist ;-)
panteradougpanteradougMember
quote:
Originally posted by Panterror:

and hopefully Avogadro (Google that one for grins Doug) will forgive me


Best,
K[/QUOTE]

6.0221415 × 1023? Hope he had a slide rule, that's a lot of scratch paper otherwise?

Glad my engineering is in structures? Just need to know how much water to mix with the Portland cement and how big to make the footings? Simple stuff. Big Grin
panteradougpanteradougMember
quote:
Originally posted by Dago:
Have a look at this........

http://www.youtube.com/watch?v=knHeUF9JLzg

That say's it all.

Arno


Not really. It only deals with one source of nitrogen.

Results suggest it is not worth buying it from that filling station.

There are two reasons I'm considering in doing it, but I would be buying my own tank of nitrogen anyway.

1) remove as much of the moisture as possible 2) Remove as much of the oxygen as possible

The 10" Campi's alone are worth the added possible protection and 15" speed rated tires aren't cheap or easy to find either.

For $100 a tank, it's worth it to me BUT ONLY if it is 100% moisture and oxygen free as delivered .
C comp2Member
quote:
Originally posted by Panterror:
quote:
Originally posted by comp2: Oxygen bleeds down a lot quicker then a gas that can be taken to liquid.


They both liquefy. Nitrogen boils at 77K (Kelvin) and Oxygen at 90K, meaning O2 liquefies at a little higher temp than Nitrogen. They are both pretty close in molecular weight O2=32 gm/gm-mole and N2=28 gm/gm-mole so a liter of liquid O2 would convert nearly as much gas as a liter of liquid N2.



That’s one heck of a bank of gas cylinders Gary.

The most significant benefit of using pure N2 is both the absence of water and oxygen. As mentioned in the thread, most aircraft wheels were magnesium and magnesium oxidizes rapidly in the presence of O2 and water so the use of N2 prevents corrosion because it is chemically much less reactive than oxygen and water completes the circuit, especially if there are dissimilar metals present (galvanic corrosion). Pantera Campys are of course mag as well.

Eliminating any water vapor should make the tire pressure a little more stable over a given temperature range. At altitude in an aircraft tire, H2O vapor will freeze and no longer contribute to tire pressure at all. The presence of H20 vapor will also make tire pressures raise more in racing situations as tire temperatures increase. Fill your tire on a hot humid day with one of those cheepo gas station outdoor compressors you pump with quarters and you will have liquid water in your tires at Winter temperatures.

You don’t have to have N2 to eliminate water. Just a good inline desiccant cartridge will do almost as well and achieve pressure dew points of <=100F and this will probably eliminate the lion’s share of corrosive activity.
In theory pure O2 would diffuse (leak) out more slowly and hold tire pressure better than pure N2 because diffusion rate is inversely proportional to the square root of density (proportional to molar mass). In other words, big molecules diffuse more slowly. But O2 and N2 are so close in molecular weight this isn’t an appreciable effect and air is in between the two so even less difference compared to air.

Other than preventing long term corrosion in mag wheels I think it’s picking the fly sh!t out of the pepper for street cars. Just buy an inline desiccant cartridge for your compressed air line and call it a day Doug.

The claims about N2 making tires last longer are usually over blown. I know, the truck stops put N2 in the over the road truck tires but they recap those things and they cost a bundle so prolonging a tire is more significant. Ozone and Ultra Violet light are the chief culprits in degrading tire rubber. You can get rid of ozone on the interior but it will still be there along with UV on the outside.

For estimating how many tire fills you can get from a compressed air tank, the volume of gas is proportional to absolute pressure. For every atmosphere of pressure (14.7 psi) increase, the volume of gas in the tank goes up x1. Most scuba tanks are referred to by how much gas they hold at rated pressure. Anywhere from 65-120 cubic feet is typical and pressures up to 3000 psi depending upon tank type. 315/35/17 is a popular Pantera tire. They’re about 2 cubic feet internal volume. So to raise pressure from completely flat (1 atm absolute) tire to 30 psi (about 2 ATMs) would take 4 cubic feet out of the scuba tank. So even the smallest scuba tank would likely fill 15 large rear tires from completely flat and would top up a partially full tire a very large number times. This assumes ideal gas behavior but close enough.

Be advised, there is a significant danger in using high pressure gas source to fill tires. As a precaution, you should have a very good regulator, an orifice to limit flow, and a very reliable relief valve on the low pressure (tire) side. Being in close proximity to an exploding tire/wheel can easily kill you.

You also won’t find an industrial gas company willing to put pure N2 into a scuba tank or another tank meant for breathing air for concern it would be stored and/or change hands and someone would assume it is full of air instead of N2 and….well, die. Take the scuba tank out of service, paint it, and identify it as not for breathing air. You will also discover the fittings on scuba (air) tanks, oxygen and nitrogen tanks conform to Compressed Gas Association standards and are all different to discourage filling them with the wrong gas. You will need to make your own conversion charging line to do so but just be careful you don’t nominate yourself for Darwin awards in the course of doing so.

Best,
K


Except I don't think they are putting liquid oxygen in scuba tanks.
rockyrockyMember
quote:
Originally posted by Joules:
The air you breathe (and currently in your tires) is 79% nitrogen anyway. IMO going full nitrogen is a waste of time and money, unless you are running in a top competition class and even then it's debatable.


I agree with Joules - I think this discussion is definately a case of diminishing returns.

The outside of your rims have significantly more surface area than the inside. IMHO - you would get better protection / longevity by giving them another coat of paint than by filling with N2.

The inside of your tires have less surface area than the outside - and the outside of the tires are exposed to Oxygen and Ozone and UV light.


There HAS to be a way to spend $100 (plus the 3 hours spent reading and writing this thread, and the time it will take to get a nitrogen setup, and to fill a tank) that will have a bigger payback than this....

But that's just my opinion.... I still have a lot of work to do to my car... I guess your car is "100% finished"....

Not to be arguementative.... Just realistic.

Rocky
accobraaccobraMember
Gents,

You can simply contact a local HVAC Tech and have him use his vac pump and pull a vac on the tire / rim assembly ... not sure if you would break the bead ... and then I'm sure on his truck he has a nitrogen tank to refill the tire ... or go to any HVAC Supplier or Compressed Gas Supplier ... your going to have to buy a Nitrogen Gauge/ Hose and leave a deposit for the cylinder ... only minor dilemma is adapting a Air chuck to a shrader fitting to adapt to a Nitrogen hose so you can fill tires.

Ron
B bdudMember
I have been using nitrogen in our road cars for many years with good results. The tire pressure does not change much between the winter and summer so I do not get the "seasonal" tps warning that sometimes happens. In many tires I have had not had to top up the nitrogen inside before it needed to be replaced through tread wear. The main reason F1 and Nascar use it is for consistent pressures. It is an additional $5 charge per tire to add nitrogen at the shop I use. If I need to add regular air at any time, the shop will purge the tire and refill with nitrogen at no charge. I am also changing some of my tires at a dealership where a friend works. Their nitrogen fill station is an automatic unit that purges the air in the tire twice then fills it for the final time. If those tires just need a top-up, I use the dried air from my compressor. Most of the cars in my family now have a winter set of wheels/tires so over all, the tires will hopefully last more years than just using the one set. I hope the nitrogen will preserve those wheels and tires better, especially the mag wheels. I also read somewhere that nitrogen is slightly lighter than air so you could get an extra oz off your unsprung weight!
panterrorpanterrorMy 74 GTS
I guess I’ve discovered I like web surfing while watching football playoffs and BCS games. I’m also a contrarian by nature and have throw the BS flag.

There is a lot of (mis)information and myths out there on the internet regarding the use of N2 in tires and most of what’s out there is complete rubbish perpetrated by those that would like you to believe it’s worth $10/tire to fill your passenger car tires with N2 as opposed to just maintaining their shop air like they should……but then would you pay $10/tire for that?

I would never have thought it possible sell ordinary consumers N2 for their tires until folks started selling bottled water for more than soda and beer….that’s marketing boys…not science but it’s still all business. So all in good fun I’m about to add to the internet content on the subject and I don’t mean to offend anyone but you can decide whether the following is fact or just more internet fiction.

The ideal gas law will very closely predict the behavior of O2 & N2 at these pressures and temperatures. Remember the old PV=nRT from chemistry class? When Volume is held constant it says the absolute pressure change is proportional to the change in absolute temperature.

At 20C, you add 273 to get an absolute temperature of 293 Kelvin. (Or if you’re not a metric kind of guy at 70F you add 460 to get 530 Rankin)

In any case, if it was a 70F day and your tire was at 30 psig (30 + 14.7=44.7 absolute pressure), and you had a 10% increase or decrease in temperature; mind you, this is +-10% of absolute temperature or 530R in this case, so we’re talking a 53F change up or down from 70F starting point, your tire pressure would change 10% absolute pressure or in this case 4.47 psi……so 30+-4.7psig for a 53F temp change from room temp.

That temperature change is realistic (and then some) for racing conditions and the corresponding pressure change is a big deal performance wise for people racing on slicks. The Pros plan for the increase in pressure because they know it doesn’t matter whether it’s O2, N2, or air as long as it behaves like an ideal gas, which these gases will if they’re (very) dry. Water does not behave ideally because it undergoes a phase change twice over the decrease in temperature in the range I mention above. If the gas in the tire is (near) saturated at 70F it will begin undergo phase change with some of the gas immediately condensing to liquid when you drop the temperature. By the time you reach 32F the water becomes solid (frost/ice) and at that point it ceases to exert any pressure at all on the tire wall. This will make the temperature change more drastic than ideal gas law predicts more so on temperature loss especially when you go through freezing.

If you search the subject most of the net info will say N2 is more stable than air. If you read on, some will go on to say it’s not actually because of O2 content, but the contribution of water vapor in shop air. Some even go onto to argue it’s because the oxygen is more reactive (which it is) and is causing corrosion and thus bead seal corrosion and associated leakage which is exacerbated by….you got it, water. Some of the articles even blather on about the solubility of O2 in rubber in conjunction with water. I’ve got a close friend that works at the local company that invented the vulcanizing process for recapping tires. They understand how tire rubber behaves. He smiles at me when I mention this to him. I’ve demounted some old dry-rotted tires that look like hell on the inside but I’ve also demounted many that look pristine on the inside. How’d that happen? It wasn’t because they were filled with N2.

A few of the internet articles will actually come out and say it’s not the N2 that is the benefit, but the absence of water.

Is N2 better than O2 (errr actually 78% N2/air)…and is it less reactive?......yup but how much better? Measurably better?

Bottom line guys, no matter what you do you are going to get the pressure fluctuation in your tire with changes in temperature irrespective of whether it’s completely desiccated N2, O2, or air and it’s not dependent upon your selection of either of these gases, unless you’re using wet shop air. Keep in mind air is 78% N2 anyway so all of this is why I said buy a $10 desiccant cartridge, run your air through it slowly to give it a chance to work, and call it a day.

Gotta go. FL State is mounting a comeback against Auburn.

Best,
K
panteradougpanteradougMember
If I am starting out at 35psi at 70F, and the temperature drops to 15F and I wind up with say 15psi that is measurable, can I calculate the amount of water that was in the air in the tire?

Sounds like I am pumping quite a bit of water vapor into these tires at 70F?

How much of that can be removed by purging and running the compressed air through a good desiccant or better yet do I need to contrive a desiccant filter system to remove a specific amount of compressed water vapor?

Should that filter be on the intake of the compressor or the exhaust or both?

Do I need to have a proportional desiccant filter size relative to the intake or exhaust of the compressor to achieve this?

Are there better substances that work as a desiccant than others?


I can see that in many instances it may be much simpler to drag around tanks of very dry nitrogen to the race track or out onto the runway to top the tires rather than have an extravagant air drying system on a small portable compressor?

That isn't a stretch to see that as a player in using nitrogen in race cars rather than very dry compressed air, i.e., nitrogen in a bottle is actually a whole lot easier to use than drying out the compressed air in a remote location?



Also, not a scuba diver here but is the amount of water vapor that is compressed into a scuba tank a consideration too?

Are you changing the safety of the breathen air to the diver by doing that or better yet shortening the life expectancy of very active scuba divers by making them breath an unnatural mixture for extended periods of time?

Any MD's here care to comment on that one? Not being paranoid here folks. I blame this all on Ray Herbert, aka, Mr.Wizrd. He ruined me for life? There wasn't anything else on tv on Sunday afternoon here. Giant home games were blacked out then. You basically only could see them play the Cowboys away on TV.



Ever walk down a straight expansion line in the sidewalk? Is it better to walk in a natural rhythm of one foot starting on one side of the
line and varying with the other?

What happens if you skip on one foot and vary the pattern? Is this the difference between sanity and insanity? OMG! I just answered my own question! Someone please help me! roll on floor
Last edited by panteradoug
panterrorpanterrorMy 74 GTS
quote:
Originally posted by Pantera Doug: If I am starting out at 35psi at 70F, and the temperature drops to 15F and I wind up with say 15psi that is measurable, can I calculate the amount of water that was in the air in the tire? Sounds like I am pumping quite a bit of water vapor into these tires at 70F?

Well, the football game is long over so I’m starting to lose interest in the subject and don’t have time to look at the steam/enthalpy tables, but yes it can be calculated. You need to know the water content of the air to begin with. You can assume it is saturated for worst case. If the air was compressed to say 100+ psi and then put into your tire at 35psi, it won’t be saturated. Search “pressure dew point”. I think I can confidently say if you lose that much pressure you also have a leak.
quote:
How much of that can be removed by purging and running the compressed air through a good desiccant or better yet do I need to contrive a desiccant filter system to remove a specific amount of compressed water vapor?

With good desicant and low flow, for all intents and purposes (at least in engineering terms, but not chemical terms), virtually all. “Pressure Dew Point” is the measure.
quote:
Should that filter be on the intake of the compressor or the exhaust or both?

It would do some good on the intake side but much better on the exhaust side, and after cooling the compressed air. Most folks rely on the tank to cool the compressed air. So in this case you extract it from the tank and put it through the filter.
quote:
Do I need to have a proportional desiccant filter size relative to the intake or exhaust of the compressor to achieve this?

It’s usually relative to the rate of flow you are putting through it.
quote:
Are there better substances that work as a desiccant than others?

Depends how elaborate you want to get. If it’s only once in a while that you need dry air, silica gel is a common and inexpensive desiccant. It usually looks like fine rock salt and starts blue and becomes clear when it’s spent. It’s cheap but you can bake the water out of it in your kitchen oven and reuse it. Caution: If you have an oil lubricated air compressor, don’t do that, chuck it. There are many other sorbemnts like activated alumina and molecular sieve that are strong desiccators too.
If you want to see best practice in managing compressed air systems for average Joes, look to the guys who paint cars. Water is a real drag that causes paint defects and blushing etc. The norm there would be to have a refrigerative dryer and possibly a regenerative (pressure swing adsorption) or semi-permeable membrane dryer downstream of that. These are common but more expensive but make sense if you need all of your air to be dry.
quote:
I can see that in many instances it may be much simpler to drag around tanks of very dry nitrogen to the race track or out onto the runway to top the tires rather than have an extravagant air drying system on a small portable compressor? That could be a player in using nitrogen as well rather than very dry compressed air, i.e., nitrogen in a bottle is actually a whole lot easier to use than drying out the compressed air in a remote location?

Agreed. As a practical matter this may be a more economical source of dry compressed gas depending upon your usage rate, cost to get yourself set up for either N2 tank, or desiccant cartridge, and frequency of use. If you need the gas infrequently or remotely, it may very well be more practical and you do have the benefit of knowing it is dry. The point I was making is it’s more so the dry gas than N2 magic from a pragmatist’s view. If you go this route, I’d suggest you not use the same neoprene compressed air line that’s used to pump water laden air through. Most of these hoses lay around on the garage floor with liquid water in them. Any dry gas will be readily pick up the H20 on the way to your tire. Maybe go buy one of those cheapy polyethylene coiled air hoses to do the job?
quote:
Also, not a scuba diver here but is the amount of water vapor that is compressed into a scuba tank a consideration too? Are you changing the safety of the breathen air to the diver by doing that or better yet shortening the life expectancy of very active scuba divers by making them breath an unnatural mixture for extended periods of time? Any MD's care to chime in on that one? Not being paranoid here folks. I blame it all on Ray Herbert, aka, Mr.Wizrd. He ruined me for life?

It’s not really the H20 in the air. We breathe it all the time. In fact, the presence of H20 in air makes breathing it more comfortable. It is an issue and in part the reason for the SCUBA bottle being worn with the valve down. The safety issue is more a matter of cleanliness and preventing corrosion. Water can breed microbes and bacteria. It also can create fouling and freezing in the regulators and breathing devices which is unwelcome at depth. SCUBA compressors are usually multiple stage recip compressors with multiple water traps, inline desiccant filters, and microbial filters at least for the pros and people that sell the service. The standards often go down for live-aboard boats and hobbyists who recharge bottles.

A couple other practical thoughts; to help appreciate how water affects ability to oxidize metals consider how cars age in the desert Southwest compared to coastal Southern Florida or perhaps add salt to the equation in the Midwest rust belt. To further consider how degrading UV light is to polymers and elastomers, have a look at the dashboards in old Arizona cars. Lastly, I just saw a set of mag GT5 wheels sell for North of $10k. Maybe N2 isn’t such a bad idea.

Kelly-Out
panteradougpanteradougMember
Thank you Mr.Wizard.

Seems like a big bottle of nitrogen in the garage is the simplest solution.

I can justafy the $100 if I can use it for something else, like it mixing well with Scotch?

You are relieved of any responsibility of response in this conversation as far as I am concerned. Wink

Thanks for sharing your knowledge.

Roger that! Big Grin
jfb05177jfb05177Member
gosh Kelly, I was really looking foward to the next class on partial and vapor pressures.

Guess I'll have to see If I can remeber how to use my "Keenan & Keyes".

Interesting, all the "adavanced articles" I find with google on the use of N2 in tires can go into detail gas law calculations, but only mention the possible ill effects of vapor.

Just my quick new opinion is that one would need to have liquid water in the tire to cause a measureable effects. But I have seen water spray from roadside air sources

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