Helium car tires

[MigL]

Maybe 'liquid' was the wrong choice of words, but look up a table of the dew point of water ( or more accurately the frost point ) at -25 deg C and 32 psi.
You'll find that the maximum concentration of water vapor that it can hold is extremely small.

And unless the air is extremely dry, moisture will precipitate out ( and freeze at said temperature ).
That's why I would post it on a science site; Get over yourself.

[Raider5678]

On 4/23/2018 at 11:48 PM, NimrodTheGoat said:

Could we therefore fill our car tires with helium to make them lighter, or even .... float? 

1

I remember pondering this question the first time I learned why some balloons floated and others didn't. I was like 6 or 7 I think.

It's a really interesting concept to think about, cars just floating overhead like there's no tomorrow. That'd be an odd sight to behold indeed.

[Bender]

3 hours ago, Raider5678 said:

It's a really interesting concept to think about, cars just floating overhead like there's no tomorrow. That'd be an odd sight to behold indeed.

Behold:

4 hours ago, MigL said:

Maybe 'liquid' was the wrong choice of words, but look up a table of the dew point of water ( or more accurately the frost point ) at -25 deg C and 32 psi.
You'll find that the maximum concentration of water vapor that it can hold is extremely small.

And unless the air is extremely dry, moisture will precipitate out ( and freeze at said temperature ).
That's why I would post it on a science site; Get over yourself.

The vapour pressure of water at room temperature is 0,02 bar, so if you inflated your car tires inside with 100% humidity, and then it all freezes, that would be your pressure drop.

On the other hand, a decrease in temperature from 293 K to 248 K , with a tire pressure of about 2 bar, will result in a pressure drop of over 0,3 bar (ignoring shrinkage of the tire) 

I don't think humidity is your problem.

[John Cuthber]

 

11 hours ago, MigL said:

That's why I would post it on a science site; Get over yourself.

 

It's not a matter of me getting over myself- it's a matter of you talking nonsense.

On 4/26/2018 at 10:26 PM, MigL said:

Don't forget I live in Canada John, liquid water in my tires are a definite possibility at -25 deg C.

If you post nonsense, don't try to "double down" on it when someone points it out.

Now, given that

liquid water isn't going to be there at -25C and

that you shouldn't have any condensed phase water in your tyres and that the

deviations from ideality  of both nitrogen and oxygen are small and

they will be similar so the differences between the behaviour of nitrogen and oxygen will be even smaller than the differences from an ideal gas

and that even if  there was bulk water in the tyres the vapour pressure would be negligible

and the changes in vapour pressure would also be negligible

and that the viscosity of nitrogen is lower than that of oxygen (so, for a given hole, it's going to leak faster)

and so on, can you give a valid reason for using nitrogen (other than that the oxygen may  percolate through the bulk rubber faster) for spending the extra money?

Carefully dried air is still cheaper than nitrogen.

It's very easy to provide air that's "dry enough" for this application; you just compress the air to a pressure that's higher then the pressure you use in the tyre, wait for any water to condense, and then expand the air down to the right pressure. The relative humidity will fall with the pressure.

 

Edited April 28, 2018 by John Cuthber

[MigL]

And again, a small difference is still a difference.
I can get my Nitrogen for free, so there is no added expense or effort on my part.

The TPMS sensors in the valve stems came out once I started running Continental run flats.

And the comment about you getting over yourself ( for which I should apologize, but won't ) is certainly not related to your knowledge/intelligence, but rather your condescending arrogance. In the time that I've been a member here, you've managed to nit-pick fights/arguments with quite a few of the members I consider  most reasonable and level headed.
Maybe telling others that they should not be posting on a science site is the wrong approach for passing on your knowledge.

[Endy0816]

Should check with a mechanical guage, that'll tell you one way or another.

[John Cuthber]

1 hour ago, MigL said:

And again, a small difference is still a difference.
I can get my Nitrogen for free, so there is no added expense or effort on my part.

The TPMS sensors in the valve stems came out once I started running Continental run flats.

And the comment about you getting over yourself ( for which I should apologize, but won't ) is certainly not related to your knowledge/intelligence, but rather your condescending arrogance. In the time that I've been a member here, you've managed to nit-pick fights/arguments with quite a few of the members I consider  most reasonable and level headed.
Maybe telling others that they should not be posting on a science site is the wrong approach for passing on your knowledge.

Thanks for pointing out that correcting  errors like "water is liquid at -25 C" constituted "nit picking".

Re "And again, a small difference is still a difference."
Yes, and like the  difference caused by changing the vehicle load, or temperature, it is inevitable.

 

If it was a problem (and it's not), using nitrogen wouldn't solve it.

 

[J.C.MacSwell]

Depending on the tires, speeds and loading, driving for half an hour at -25C could easily raise the tire temperature above the melting point of water.

https://www.caranddriver.com/columns/a-look-behind-the-tire-hysteria

[dimreepr]

1 hour ago, John Cuthber said:

Thanks for pointing out that correcting  errors like "water is liquid at -25 C" constituted "nit picking".

Well just to nitpick...

https://www.seeker.com/waters-ultimate-freezing-point-1765534898.html

[John Cuthber]

10 minutes ago, dimreepr said:

Well just to nitpick...

https://www.seeker.com/waters-ultimate-freezing-point-1765534898.html

Thanks for clarifying the distinction.

Pointing out that  liquid water might exist at -25C, but not in conditions that would be found in a car is irrelevant, and, therefore, nitpicking.

25 minutes ago, J.C.MacSwell said:

Depending on the tires, speeds and loading, driving for half an hour at -25C could easily raise the tire temperature above the melting point of water.

https://www.caranddriver.com/columns/a-look-behind-the-tire-hysteria

And the change in temperature would significantly alter the pressure- just because hot gases try to expand.

That effect is going to exceed any effect from water vapour pressure or any difference between air, oxygen, nitrogen or helium.

 

[J.C.MacSwell]

3 hours ago, John Cuthber said:

Thanks for clarifying the distinction.

Pointing out that  liquid water might exist at -25C, but not in conditions that would be found in a car is irrelevant, and, therefore, nitpicking.

And the change in temperature would significantly alter the pressure- just because hot gases try to expand.

That effect is going to exceed any effect from water vapour pressure or any difference between air, oxygen, nitrogen or helium.

 

The effect is additive so can still be significant.

Let's say you fill up your front tires with air from a compressor on a hot humid day in the summer time. You make sure to make the pressures equal. You do the right side of the vehicle with dried air but the left you simply compress air and pump it in moisture and all. Drive for a while and the pressure increases in both tires as they heat up but will be greater for that on the left. Wait for a cold day in the winter and both tires will have dropped in pressure but again the difference will be greater for the left, as some of the vapour will have condensed.

The main point of course is that that left tire can in fact have liquid moisture in it at -25 C. It could be quite likely to under driving conditions after it is warmed up...something you assumed was not the case when you jumped on MigL...unless of course you knew it all along but thought it was still OK to think he claimed the "water is liquid at -25" when that was not what was stated, whether his wording was in error or not.

[John Cuthber]

2 minutes ago, J.C.MacSwell said:

The main point of course is that that left tire can in fact have liquid moisture in it at -25 C.

No

3 minutes ago, J.C.MacSwell said:

You do the right side of the vehicle with dried air but the left you simply compress air and pump it in moisture and all.

Not treating tyres reasonably symmetrically is obviously a bad thing.

It has nothing to do with nitrogen or He vs air.

5 minutes ago, J.C.MacSwell said:

The effect is additive so can still be significant.

And the effect will be the same with He, N2 or O2.

[J.C.MacSwell]

Just now, John Cuthber said:

No

...on a typical -25 degree day...while/after driving...liquid moisture in tire...are you having trouble with the context of the wording or the science?

[John Cuthber]

 

1 minute ago, J.C.MacSwell said:

...on a typical -25 degree day...while/after driving...liquid moisture in tire...are you having trouble with the context of the wording or the science?

No

I'm having trouble seeing why you say 

 

9 minutes ago, J.C.MacSwell said:

have liquid moisture in it at -25 C.

When the water you refer to  is not at -25C

The ambient air (or the road) might be but the water isn't.

And, it's very  poor practice to have any condensed water in the tyre.

11 minutes ago, J.C.MacSwell said:

Some of the vapour will have condensed.

How much difference will that make?

How accurate is the gauge? 

[J.C.MacSwell]

4 minutes ago, John Cuthber said:

 

No

I'm having trouble seeing why you say 

 

When the water you refer to  is not at -25C

The ambient air (or the road) might be but the water isn't.

And, it's very  poor practice to have any condensed water in the tyre.

OK. So you could not infer from my explanation that it was -25 C ambient condition and when the tire heated up, as it must, it (the tire) was...no longer -25C?

Edited April 28, 2018 by J.C.MacSwell

[John Cuthber]

Why not actually say what you mean rather than repeatedly saying something plainly not true?

[J.C.MacSwell]

3 minutes ago, John Cuthber said:

Why not actually say what you mean rather than repeatedly saying something plainly not true?

So you didn't understand? You thought I meant that it heated up, but stayed at the same temperature? That's what you got out of it? 

[John Cuthber]

Water at -25 in a tyre is not liquid.

So, it is plain wrong to say " liquid water in my tires are a definite possibility at -25 deg C."?

Now, perhaps you could get back to my question.

How much does the vapour pressure change by?

 

[Bender]

26 minutes ago, John Cuthber said:

How much difference will that make?

How accurate is the gauge?

Let's focus on this instead of bickering over a confusingly worded sentence, which isn't really relevant (for the pressure it doesn't matter whether the water is liquid or not).

[StringJunky]

20 minutes ago, Bender said:

Let's focus on this instead of bickering over a confusingly worded sentence, which isn't really relevant (for the pressure it doesn't matter whether the water is liquid or not).

[J.C.MacSwell]

43 minutes ago, John Cuthber said:

Water at -25 in a tyre is not liquid.

So, it is plain wrong to say " liquid water in my tires are a definite possibility at -25 deg C."?

Now, perhaps you could get back to my question.

How much does the vapour pressure change by?

 

I guess it is impossible to drive a combustion engine car at -25 C so the tires would not heat up anyway.

[Endy0816]

Here's consumer reports talking about it:

https://www.consumerreports.org/cars-why-tires-go-flat-in-cold-weather/

 

Peesonally haven't this seen much due to cold weather, but have  when filling air tanks. Either have to cool, overfill(Caution!) or fill let cool then fill again.

https://www.trails.com/facts_22657_why-cool-scuba-tanks-filling.html

[John Cuthber]

11 hours ago, Bender said:

Let's focus on this instead of bickering over a confusingly worded sentence, which isn't really relevant (for the pressure it doesn't matter whether the water is liquid or not).

Good point.

And, to give credit where it is due,  you already answered the question

On 4/28/2018 at 6:52 AM, Bender said:

The vapour pressure of water at room temperature is 0,02 bar, so if you inflated your car tires inside with 100% humidity, and then it all freezes, that would be your pressure drop.

On the other hand, a decrease in temperature from 293 K to 248 K , with a tire pressure of about 2 bar, will result in a pressure drop of over 0,3 bar (ignoring shrinkage of the tire) 

I don't think humidity is your problem.

If you had bulk water (as liquid or solid) in your tyres you would  be treating those tyres badly.

But the effect of changes of vapour pressure would be small compared t the effects of thermal expansion.

 

 

11 hours ago, J.C.MacSwell said:

I guess it is impossible to drive a combustion engine car at -25 C so the tires would not heat up anyway.

A stably running heat engine doesn't have a temperature.

It has at least two- you can use them to calculate the theoretical thermodynamic efficiency.

 

On a related, and probably a more interesting, note (it's not difficult).

Are there any native French speakers reading this?

I seem to recall hearing that the translators struggle to translate the common English phrase "room temperature" into French because there's no simple equivalent.

Is that true?

[J.C.MacSwell]

3 hours ago, John Cuthber said:

 

A stably running heat engine doesn't have a temperature.

It has at least two- you can use them to calculate the theoretical thermodynamic efficiency.

I knew you would get it...but +1 for explainining

[MigL]

 could have PMed you but I thought it would be better public...

I apologize for my comments John. I have gotten along with other blunt people who speak their mind, such as Ophiolite and Dr Rocket, and I assure you, I respect your opinions as much as I did theirs.

Its not much of an excuse, but you caught me on a bad day and I took it out on you.

Incidentally ( to get back on topic ), enthusiasts do all sorts of things with negligible ( or even non-existent ) returns. That is the very definition of enthusiast. Do you think people collect stuff for its monetary value ? Do you think people can tell the difference between a transistor Amp and a tube Amp, or $1000 speakers and $15000 speakers ?
So while you may argue that the difference between air and Nitrogen is negligible, to an enthusiast, it isn't