Tire fill: Something different in the air
 

I will be trying to attain measureable results from filling the tires with something besides air, or nitrogen.
Since I already tested nitrogen years ago and found no measureable difference from air. Makes sense since air is almost 80% nitrogen. You would expect there to be little difference.

I am going as unair like as possible, while staying with non flammable and non oxidizing gases.
Since summer is coming in New Mexico, a lot of roads have been repaved, making them extra black and there for extra hot. I am going to test cooling gasses on hard working trailer and truck tires.
Possible cooling gasses are any heat pump working fluid or inferred absorber.

I dont plan on it saving a bunch of fuel. I am looking to save tires. At $50 to $80 each not blowing them is pretty economical, not crashing even more so.
My winter test will be aimed at saving some fuel in car tires.

How can I do this? Well I keep inert shielding gasses on tap in pure form to mix on site to feed my welding machine. I have CO2, Argon and Helium. Helium is the most expensive by far. I also have refrigerant, a blend R-404a has caught my attention.
To get the gas into the tire I built a tire gas manifold to unite the welding world, HVAC worlds and bring them to the tire world.

Because I am too cheap to waste gas, even if its $1/lb CO2 doing a bunch of purging I will attach a vacuum pump to the tire manifold. Pumping some of the air out of a tire and then filling will have the same effect as preforming 1 or 2 purges.

First tests will be to make sure any of the gasses used for on road tests dont permeate out at some catastrophic rate.
I already tested this with CO2 and it stays where its put.
Next test will be to fill a small trailer tire with helium and see how fast it leaks compaired to its air filled twin.
Then working up to on road tests with varrious gas mixtures.
Filling a tire with something different and hitting the road, not a good idea.

CO2 seems to like absorbing heat through conduction and absorbing IR. And its not a bad refrigerant, just expensive to employ.
Helium likes to move heat really fast. But is the most expensive by far and the most likely to leak out at a higher rate.
Argon, unlike CO2 and Helium likes to move heat more slowly, much more slowly than air.
R-404a is already a mix. The 2 main ingredients are "canned air" and fire suppressant, both are very good heat movers.

So we know refrigerants are used to transfer heat from one area to another using the compressor some valves and a condenser.
What is your theory , why you can cool a tire with a refrigerant when the heat is not later removed from the refrigerant ?

Or what is your hypothesis with using this gas ?

How worldly of you... :thumbup:


Subscribed.

>

My theory is that you're going to eventually be on the news after you blow yourself or somebody else up.
There's no reason any of those gases would pull any measurable heat out of your tires any more than the nitrogen would, and it also seems kind of irresponsible to test your theory on the road with no idea how those gases react with the tire material under heat & load, while pulling trailer loads of welding equipment. You could probably keep liquid propane in a tire, buy I doubt that you'd really want to drive around on it

In some related threads, there was talk about the heat capacity of various gases - and there is some considerable difference. I suspect the actual difference in operating temperature would be minimal.

But you haven't told us what you are gauging. That is, what is the thing you are measuring to see if there is a difference. How does that relate to things?

But good luck with the experiment.

How differently do these gases expand when heated?

Perhaps I can answer that.

Not much differently. Pretty much all gases at the temperatures and pressure we encounter behave close to the Ideal Gas Law: PV=nRT.

Measurements will be looking for swings in pressure with temperature.
This will be part of the non road test, fill the tire at night to a set pressure, lay it down on the ground where the sun will hit it, let it get good and hot to simulate being driven and check pressure again. I am not expecting much to happen.
The result I am looking for in the cooling test for the tread package to run cooler. Tread slightly cooler, side wall and rim, slightly warmer.
If the complex gasses stay in the tire longer that would be nice too, (the idea behind stayfill).


Did you read the post?
There is an entire pre-onroad phase to this.
I know the gases I am going to test have been used on road or track before.
A company called stayfill sell a fluorocarbon to fill vehicle tires, likely HFC-125 (fire suppressant), R-134a, or "canned air" aka R-143.
Plus how is fire suppressant going to blow up?
You spray into a room full of fire and it goes out, if that's not a definitive test than I dont know what is.
An R-404a mixture was used in F1. Do you think if it were going to blow up they would use it?
No of course not :rolleyes: .

I'm interested in the results of this, but uninterested in the sense that the results won't amount to any practical application.

The various gasses are infinitely more expensive than (free) air, and will not have significantly better operating properties.

The only way a different gas could keep the tires cooler is to more readily absorb heat, and then transfer it to the wheel. Heat conduction is the property of the gas that would be important here, and the conduction rate can be looked up for the various gasses.

That said, helium would be more dangerous since it will leak out rapidly, requiring a pressure check before each trip.

Further, each time you check the tire pressure, you loose a little bit of pressure. I wouldn't be surprised if you loose 0.5 psi each time you check a trailer tire. This, along with the other variables of heat expansion and the tire just loosing gas will muddy the results of the test, since these variables aren't tightly controlled.

I know that is a lot of negative talk about the experiment, but I'm still curious to read the results, and I think it's great that Oil Pan has the motivation to take on such a test and share the results with everyone. :thumbup:

i'm in for the results. good luck.
maybe have wireless psi/temp instruments IN the tires. can't lose pressure that way.

Some things you might not be aware of:

Tires, when first mounted, expand greatly in the first 24 hours - to the point where people who do this regularly add 2 to 3 psi over the target, so that it will be on target after the tire grows.

Second, even tires that have been deflated, then re-inflated suffer from a lesser form of this.

So I'd recommend mounting the tire for 24 hours before starting the test and readjusting the pressure at the start. That reading should be taken in a stable environment - room temperature.

You need to have a sensitive pressure gauge. I think one with tenths of a psi will work.

And lastly, as an end point, you ought to return the tire to its original condition (at room temperature) and check for leakage by measuring the pressure 24 hours after it is returned to that stable environment. THAT reading should be the same as the first one. If not, you have leakage that invalidates the test.

Ok these are all tires that are between several years old, to brand new tires mounted on the rim within the last month or so but have seen 0road miles.
My gauge does half psi.

I'm mostly interested in seeing what the tires look like with vacuum in them. ;)

I dont try to pull a high vacuum. I figure tires are made to hold pressure in, not the other way around.
I put the air powered vacuum pump on it and let it pull air out till the side walls suck in a little bit.
Then it takes a lot of CO2 to bring them up to 30psig.

So far they have been holding CO2 like a champ.

Next step will be to bleed the CO2 down to 15psig, then bring it up to 40psig with R-404a.

Next time I fill with CO2 I will weigh the bottle before and after.

The CO2 test was on going for a few weeks. About as exciting at watching grass grow.
Tired of that I decided to spice things up a bit.
So I deflated my CO2 test tire from 40psig to 15psig. Then brought them up to 40psig with R-404a.
Then rolled it out in the sun and dropped a sheet of aluminum in front of the tire to act as a reflector to heat the tire up faster. Almost immediately the tire surface temperature jumped up 50°F. The back side of the tire heated up 12°F in about 5 minutes.
This translated to a 2psi pressure rise.
An increase of 5 to 6 degrees F on the shade side of the tire resulted in another 1psi increase. At the same time the sun side temperature had risen another 10°F.

Its looking like with the 50/50 CO2/R-404a mixture I am getting almost a 1psi change for every 10°F in temperature change.

I did a test like this on tires if purged and filled my self with 95% nitrogen back in 2006 and saw something like a 1.5 psi change for every 20°F change.

So the CO2/R-404a mixture only changes pressure with temperature slightly more than nitrogen. Nitrogen according to some people doesn't change pressure as it heats up. :rolleyes:

http://ecomodder.com/forum/showthrea...tml#post255838

Since immediate catastrophic failure has been ruled out it may be time to start limited on road testing, where 1 tire is filled with the mystery gas and the other 3 regular air.
So far my test tires have been with 2 brand new yokohama 30 inch load range C highway tires, that I purged and filled with CO2 and then took one tire forward with the R-404a test. These tires have been on rims and filled with air for a few months before I started messing with their inflation media.

I would also like to know whats going to happen this winter to these tires. Unfortunately I do not have a time machine. But a refrigerator and small trailer tire small enough to fit in said refrigerator should work in place of a time machine.

To be environmental friendly, save the O-zone (*cough* BS *cough*) and be cheap I have set aside an old empty R-134a tank that I can pump down to a vacuum and recover my tire gas. Soon I will have a compressor I can use to pull tire gas out of a tire and force in to a bottle. Then I have more tanks I can store gas in once the compressor is up and running, I dont think these other tanks will survive pulling a vacuum inside them.

The helium biasply trailer tire test will be soon. This test will just be to see how fast it leaks out.

Yes, some folks believe that old wive's tale.

But I disagree about the gases behaving differently.

The Ideal Gas Law predicts a 12°F change for every psi change, and 18°F for 1 1/2 psi. Looks like good correlation there for the data you are getting regardless of the gas. (Keeping in mind you are only able to measure the pressure to 1/2 a psi.)

I believe you are correct.
The Nitrogen tire testing was more controlled.
The gas mix tire was heated by the sun and aluminum reflector.
My difference between the N2 tire test and the gas mix test was about a half PSI difference between the 2, that difference was likely caused by even heating of the N2 tire versus the uneven heating of the gas mix tire.
The gas mix test scope was to heat the tire up as much as possible from the base line to see if there were any wild pressure swings.

I thought there would be a much wider pressure swing with the R-404a mixture, because of the way refigerants act in a refrigeration system.

[QUOTE=oil pan 4;430103]
My difference between the N2 tire test and the gas mix test was about a half PSI difference between the 2, that difference was likely caused by even heating of the N2 tire versus the uneven heating of the gas mix tire.

you have a pressure gauge accurate to 0.5 psi and you are using a recorded difference of 0.5 psi as significant data?

so... um... well good luck with the research.

I think he is expected much more then a .5 psi difference,
That .5 psi measurement shows there is little to no change.
Should be fine using a psi gauge with 0.5 psi increments as any psi change that size and smaller can be classified as no change.

As has probably already been mentioned, air is ~78% nitrogen, so the remaining ~22% has to be pretty huge effect. Most of the 22% is oxygen - which is on the outside of the tire, anyway.

http://en.wikipedia.org/wiki/Atmosphere_of_Earth

sure, it just seems pointless to go through the procedure and not get any data. 0.01 - 0.99 2.48% change at 40 psi. could be significant. with the cost of the gasses being used, why not buy a better gauge and have some data that is usable.

If you cooled a tire filled with 100% R-404a down to -20 deg F, the pressure would drop to 31 PSIA, or 16.5 PSI on the tire gauge because some of the R-404a would condense to a liquid.

If the tire is filled with 100% R-404a until the R-404a is a mixture of gas and liquid, then the pressure will be the saturation pressure listed in the refrigerant data sheet. That would be 150 PSIG at 70 deg F and 450 PSIG at 150 deg F.

I would expect gases with larger molecules, such as CO2 and R-404a, to have lower lead rates.

[QUOTE=bryn;430109]The gauge is graduated in half psi increments. The gauge is dead on other wise.
I know this because I checked it against a master gauge calibrated in 1/4 psi increments.
Unfortunately I do not have a climate controlled lab with double precision instruments, but my measuring equipment is a lot better than what most people have.

Alot of people have tire pressure indicating tools that cant even detect a pressure change in their tires after driving. This is partof the reason people believe nitrogen doesn't change pressure in a tire as it heats up.

I am not developing a temperature pressure chart for this gas mixture. All I need to beable to do is detect wild pressure swings and accelerated leak down for CO2 and helium.

There's no reason any of those gases would pull any measurable heat out of your tires any more than the nitrogen would, and it also seems kind of irresponsible to test your theory on the road with no idea how those gases react with the tire material under heat & load, while pulling trailer loads of welding equipment.

Argon and Helium should not react at all with the tire material, they are both ideal gases of group 8 on the periodic table with full valencies meaning they do not react unless under extreme conditions, (I doubt the inside of a tire at a higher temperature is a concern). If the CO2 were to react the only reaction it would undergo is an oxidation reaction where it would gain another oxygen and become carbonate, again unlikely given the conditions and the carbonate would not react with the tire material as it would be a very weak base. The refrigerant might react, it depends on what its chemical make-up is.

Oh really?
I noticed they don't use nitorgen in fire suppression systems.

Well I don't think there will be any on road helium tests. I am expecting helium to leak out really fast.

Did you read any of the other posts?

All the likely canidates used in stayfill are found in R-404a.
My money is on "canned air" (R-143a).
CO2 is widely used to fill tires on motor cycles, according to stayfill CO2 is the main bottled product they compete against.
Street legal off road and jeep guys often use CO2 to fill their tires after going off road before the drive home.
CO2 is very stabile.

These numbered "R" chemicals are stabile to some where in excess of 400'F. At those temperatures the tires is likely on fire already, then at that point would you rather have a tire filled with air, or fire suppressant?

And why does everyone assume this is going to be a welding trailer. I live in the ghetto. The trailer will not fit in the garage and it wont fit in the back yard. If I left welding equipment out side on the trailer crack heads would decend on my valuables like roachs on a chinese restraunt after hours. Anything they couldn't steal, like something bolted to the trailer would have leads cut off or be broken from attempts to pry or hammer it free.
Or they would just steal the trailer, contents and all.

The heaviest load I plan to carry on this trailer is water tanks filled with water. Or stranded electric vehicles. :p

I weighed my mostly finished tandem axle trailer. It weighed in at 1720lb with no wood decking or tool boxes.

Just so we are all on the same page:

The point of the test is to simulate the heat buildup in a tire and see how that impacts the pressure buildup. Oilpan4 says he doesn't expect much, but he never explained why. I suspect it is because the Ideal Gas Law is a pretty good way to predict pressure buildup.

But the one thing that jumped out at me when I reviewed the posts in this thread was that using the sun to simulate the heat buildup in a tire was somewhat non-analogous. That is, the heat in the air chamber of a tire comes from the hysteretic properties of the tire components (mostly the rubber) and that is not uniform around the perimeter of the tire. The tread will generate more heat than the sidewalls because the tread has much more material that is being moved.

And I think the point of using a different gas in a tire (ala F1) was to move that heat away from the tread area to an area where it could dissipate - like the sidewall. The net effect would be to slow the heat buildup internally to the tire, and to speed the cooling down. In F1, this would help preserve the tires, plus allow the driver to push for a longer period, then have less time to cool the tires down before having another go at fast laps.

Yes heating the tire in the sun with the help of a sheet of aluminum was the next best thing to driving it on road.

This gas mixture in the tire at normal tire pressure and temperature will act a lot more like an ideal gas than the working fluid all by its self in a charge bottle.

being a tire sucks
 

Here is a bias ply, 8 inch rimmed trailer tire with the air pulled out of it.
I pulled a gentile vacuum, filled to 30psi with CO2. Blead CO2 down to 23psig and filled with 404a till it was at 55psi.
The max pressure on the side wall is 60psi for this tire.
Looks like this will be the first on road test.

After weeks of checking pressure on CO2 filled and CO2/404a filled tires, yeilding results about as dramatic and dynamic as watching a tree grow. Its time for another small step.

Since I filled the 8 inch rim trailer tires with the mixture and they are small enough to fit in the freezer so I put a tire in the freezer for about 6 hours.
When i removed it the metal rim was showing 4°F to 5°F and the tire its self was less than 10°F.
Pressure dropped to 42psi over about a 85°F temperature change.
That was less of a pressure drop than I was expecting.
So the danger of it getting cold out side and making the tires go flat has been removed as a possibility.

and paint drying.

I sold the trailer that had the tires I was going to test the helium fill with. That one is off the table for now.
I need to pick up a spare tire for my small tired trailer and could do the helium fill test then.

I took the trailer tires filled with the mixture on their first voyage. They were my 4.8x8inch load range B bias ply tires used on my aluminum trailer, tney were on my trailer when I originally bought it. We took 200lb of steel to be recycled at the scrap yard.
These tires are rated around 440lb each. The weight of the trailer plus the load of scrap put them at about 50% capacity.
And it worked. No catastrophic failure, or any failure, deficiency of any kind.

This was a 2,000lb trailer, but I reduced its capacity when literally sold the 12inch 990lb each load range C tires out from under it. They were 5 years old, made a trip to Maine and 2 trips to virginia and back so they were getting warn down and some one offered me $50 for them, think I paid $75 each for them and I have definitely gotten my $150 out of them. I like how the trailer sits low to the ground with these 8inch wheels, makes it easy to load and unload. To restore its 1 ton capacity I will not be buying tall narrow 12 inch wheels again. Instead I will buy and install brand new 5.7x8inch load range C wheels rated for around 1,020lb each, costing around $56 each.

Went 100 miles with my fancy tire air in my 8x18 foot deck over trailer with a car on it, in the texas heat, 100 miles each way.
Nothing happened, they just did their job.
Until now this trailer had just been driven around town and to the next town over in cooler weather.
One of the tires had a slow leak, leaked down to 20psi and refilled with air. I am just going to keep refilling the slow leaker with air. The others will be topped off with, CO2 one time then 404a the next, as needed.

I have had the smaller tires on the 4x8 trailer on there now for months and done lots of small tows. They are still fine.

How about water?

Bean bag beads?

One thing that keeps nagging on me is what those gases will do when it gets cold; condensation may occur and make the tire collapse.

CO2 is unfit for winter use up north as it will condensate at near atmospheric pressure when it gets really cold.
R-404a condensates at room temperature at pressures higher than tire pressure, but not that far off. I don't know the exact condensation point for that but suspect it lies at an even higher temperature than CO2.

It would be interesting to know what happens when you fill a balloon or such with your mixture and put it in the fridge.

See post 32, I already tested it down to 5'F.
That is about as cold as it normally gets here in new mexico.

I see. Sorry for that. Good to know it works in the cold too.