Tire pressure using Co2 cartridges

[64Paramount]

I searched the forums and found some info on this, but nothing really definitive.

Has anyone tested maximum tire inflation PSI achieved using CO2 cartridge inflators?

I just bought a new inflator and I'm not sure how many PSI a single 16 gram cartridge is capable of on a 700x25 tire.

Has anyone tested that?

 

[Cipher]

According to Innovations packaging, a 12 g CO2 will fill a 700x23 tire to between 90 and 100 psi. A 16g CO2 cartridge will fill a 700x23 tire to approx. 125 ~ 135 psi.

 

[davereo]

I searched the forums and found some info on this, but nothing really definitive.

Has anyone tested maximum tire inflation PSI achieved using CO2 cartridge inflators?

I just bought a new inflator and I'm not sure how many PSI a single 16 gram cartridge is capable of on a 700x25 tire.

Has anyone tested that?

I never did check into this but I did have a problem blowing out a tube this past February with a CO2 inflator. Is there any information about using these during the winter that someone can share?

 

[Froze]

I haven't heard of any issues with CO2 in cold, and I live where it does get cold.

More then likely you pinched your tube between the tire and the rim and then inflated it rapidly and BOOM!! Or the tube was folded or twisted inside the tire then with the rapid air intake and...well you know what happened.

 

[davereo]

I haven't heard of any issues with CO2 in cold, and I live where it does get cold.

More then likely you pinched your tube between the tire and the rim and then inflated it rapidly and BOOM!! Or the tube was folded or twisted inside the tire then with the rapid air intake and...well you know what happened.

I would lean towards twisted as a culprit because I have a routine I follow to check for pinches whenever I mount a tire. I will rule out the inflator.

 

[tafi]

I searched the forums and found some info on this, but nothing really definitive.

Has anyone tested maximum tire inflation PSI achieved using CO2 cartridge inflators?

I just bought a new inflator and I'm not sure how many PSI a single 16 gram cartridge is capable of on a 700x25 tire.

Has anyone tested that?

It can be calculated using ideal gas laws.

You know the mass of CO2 in the canister (16g or 0.36 moles of CO2) and the volume is given by Genuine innovations as 21cc.

It's also not hard to calculate the volume of the inflated tube (it is approximately a torus). I make it about 995cc for a 25mm tyre.

When fully inflated the tyre and canister will be at the same pressure (fluid can only move by itself when there is a pressure difference).

High school physics or chemistry gives us PV=nRT
V = volume of tyre + volume of canister = 1016 cc
n = number of moles = 0.36
R = universal ideal gas constant
T = temp = lets say 20C or 293K

gives P = 128psi
if the temp is 0C or 273K then the pressure is 118psi
So there's not much variation with temperature.
Of the original mass 15.67g ends up in the tyre and 0.33g in the canister.

This is all only accurate to within a few psi as I have assumed there are no leaks, and I'm probably within a few percent of the correct volume.

This is really as good as you are going to get as far as knowing what the pressure will be. And anyway, why would it matter? The CO2 is for an emergency fix so we don't really care how high the pressure is, as long as it is "enough".

 

[Froze]

Huh?

 

[davereo]

Huh?

Translation if one canister is not enough hopefully you have two....LOL

 

[tafi]

"Enough" is enough to get home on. Most people get home on 70 or 80 psi so a 16g canister will be more than enough for any on-road repair (provided you don't bugger it up and release all the CO2 to the atmosphere - in which case you will need two).

 

[Froze]

Personally I don't rely on CO2 for the simple reason that you have a limited air supply. With a pump you have unlimited air supply. Just don't buy a mini regardless how many psi their rated to obtain because you'll be lucky to reach half of their rated max! Now there are some good medium size mini's, those can get to 90-100psi, but don't even expect those to reach 130 as some claim they will.

 

[alienator]

"Enough" is enough to get home on. Most people get home on 70 or 80 psi so a 16g canister will be more than enough for any on-road repair (provided you don't bugger it up and release all the CO2 to the atmosphere - in which case you will need two).

I've ridden exclusively with CO2 inflators for 6 years and have never had a problem. I carry 3 canisters. The only way I can see venting a lot of CO2 into the atmosphere is by the tube/tire's valve stem getting frozen in the open position. This happens occasionally but is easy to fix. The only other thing to keep in mind is that the next day, the tire w/ CO2 in it will be pretty flat as butyl rubber and especially latex are pretty permeable to CO2.

A bonus is that with rapid emptying, the canisters get very cold and thus feel great against the skin in the hot desert.

 

[dhk2]

tafi, not sure if everyone appreciates your calculations, but I do. It's great to have a physics prof around to remind us how a knowledge of physics really can be useful in the everyday world. Good refresher on the Ideal Gas Laws!

alienator, my experience with CO2 has also been good. I carry the 12g carts for emergency inflation on 23mm tires. Haven't needed to use one in the last couple of years, but on a hot group ride they are certainly a lot easier and quicker than resorting to the mini-pump.

 

[64Paramount]

........This is all only accurate to within a few psi as I have assumed there are no leaks, and I'm probably within a few percent of the This is really as good as you are going to get as far as knowing what the pressure will be. And anyway, why would it matter? The CO2 is for an emergency fix so we don't really care how high the pressure is, as long as it is "enough".

If the pressure is high enough to blow the tube I just replaced, then yes, I care about it....

 

[alienator]

If the pressure is high enough to blow the tube I just replaced, then yes, I care about it....

That shouldn't be a problem Besides, you can regulate the flow of gas with your inflator, right? I just inflate the tires until they feel right, when I'm doing that with the CO2 inflator. I don't carry a pressure gauge on rides. Using feel is probably the most inaccurate method of gauging tire pressure, but it's all I've got on the road. I can do it well enough to finish the ride.

 

[Froze]

I don't have to go by feel, I use a pump, and when the pump won't put anymore air into it I know I'm somewhere between 100 to 105 PSI, which is all the air I put in my tires anyways.

 

[dhk2]

12g CO2 carts are plenty for a 23 mm tire IMO. The full shot gets about 95 psi, plenty to get me home without a worry. Cheaper and lighter to carry than the 16g carts, and no fear of overinflation.

 

[64Paramount]

That shouldn't be a problem Besides, you can regulate the flow of gas with your inflator, right? I just inflate the tires until they feel right, when I'm doing that with the CO2 inflator. I don't carry a pressure gauge on rides. Using feel is probably the most inaccurate method of gauging tire pressure, but it's all I've got on the road. I can do it well enough to finish the ride.

I just bought the inflator and I haven't used it yet because I didn't want to waste a $2.50 cartridge just testing to see how it works. The instructions that came with it are very minimal, but yes, I believe I can regulate how much gas I put in the tire.

I don't carry a pressure gauge on rides either, and I wasn't sure if I should just use a whole 16 gram cartridge, or if I would need inject small amounts of CO2 into the tire till it "feels right". Hence my original question....

I'm using 700x25 tires and the inflator I bought is an Innovations Air Chuck SL. Innovations has some fancier inflators, but this one looked like it was the smallest, and space is an issue for me.

 

[alienator]

I don't carry a pressure gauge on rides either, and I wasn't sure if I should just use a whole 16 gram cartridge, or if I would need inject small amounts of CO2 into the tire till it "feels right". Hence my original question....

I'm using 700x25 tires and the inflator I bought is an Innovations Air Chuck SL. Innovations has some fancier inflators, but this one looked like it was the smallest, and space is an issue for me.

Aha! That's the same inflator I use, and I also use 25mm tires. You won't have any worries. The only issue I ever have is that occasionally the tire valve freezes open. That's an easy fix, as I just screw it shut. Not much leaks out at all when that happens. Just remember that the next day you'll have to inflate the tire, again, this time with air because butyl and latex are much more permeable to carbon dioxide.

 

[davereo]

I just bought the inflator and I haven't used it yet because I didn't want to waste a $2.50 cartridge just testing to see how it works. The instructions that came with it are very minimal, but yes, I believe I can regulate how much gas I put in the tire.

I don't carry a pressure gauge on rides either, and I wasn't sure if I should just use a whole 16 gram cartridge, or if I would need inject small amounts of CO2 into the tire till it "feels right". Hence my original question....

I'm using 700x25 tires and the inflator I bought is an Innovations Air Chuck SL. Innovations has some fancier inflators, but this one looked like it was the smallest, and space is an issue for me.

I have two different inflators and the inovation air chuck sl being one is not precise. Once the cartridge is pierced you operate the flow by turning the cartridge counterclockwise to release gas and clockwise to stop all while holding the inflator on the valve stem. The fancier inflators do not take up much more room because you can store a one cartridge inside them. They also work a lot easier being trigger activated upon piercing the cartridge.

 

[alienator]

I have two different inflators and the inovation air chuck sl being one is not precise. Once the cartridge is pierced you operate the flow by turning the cartridge counterclockwise to release gas and clockwise to stop all while holding the inflator on the valve stem.

This is absolutely NOT how it works. It's a simple push-to-inflate, uhm, inflator. Pushing a lot opens the valve all the way. Pushing a little opens the valve a little. Note that the valve is preloaded by an external spring.