Compressed gas for inflation

Does anyone have experience with CO2 (or other compressed gas) for inflating tires? A friend of mine uses the 10# Smittybuilt tank and claims to get 16 fills out of each tank, which I assume is 16 individual tire fills. I'll also assume (after today's experiment) that he's inflating from 15->25 or so, not 13->32 as I did. I'll ask next time I see him.

So I did an experiment and did not have great results. First test is with a 5# CO2 tank and the second is a 40cuft nitrogen tank. Started at 13psi in all 4 tires and target was to inflate to 32psi. CO2 tank started at about 690psig and N2 at about 2030psig. The CO2 tank totally drained before finishing, the tank and tires were at 30psig. The nitrogen was much better, filled the tires and had 840psig remaining. However, each of these cylinders is about $20 to fill, so clearly this is not a cost effective method to inflate tires. How does this compare to anybody else's experience?

Let's check with math. Assuming the 35x12.50R15's have 1" of tread/wall & 1/4" side walls thus can be approximated as 33x12.00R15, we get a water capacity of 8143 cuin = 133 liters. The internet tells me that my 40 cuft N2 has a water capacity of 7.8 liters. At 2,030 psig, that's 15,834 psi-liters (weird units, I know, but the math works). So now we fill four 133 liter tires from 13 to 32 psig, that's 10,108 psi-liters. This should mean I have 5,726 psi-liters remaining, or 7.8 liters at 734 psig. 734 psi theoretical versus 840 psi measured is pretty close - with big assumptions like this I'd say an order of magnitude off is wrong and within a factor of 2 is right. In conclusion, the math and the experiment shows that this is a poor method to fill tires. So fill me in on your experience!

Because people like pictures:
[IMG]http://evanbeloni.com/4wd/xjbuildpics/2014_moctis/moctis-03.jpg[/IMG]

I see this thread, but it did not answer my questions: [url]http://www.frontrange4x4.com/forums/showthread.php?17869-CO2-tank-question/[/url]

I use a 10 pound Smittybilt CO2 tank and run 25 psi on the street and 10 psi on trail (sometimes a little less). I get 16 fill ups (4 x 4 tires) or 4 runs, however you want to look at it. I believe I can go one more but I use 4 runs as my self imposed refill count. Also it gives a little fudge factor if anyone pops a bead or needs help filling up their tires after a run.

I found a grow shop that fills it for $12. That's usually $24-$36 a year for me. Other than the speed of inflation the other thing I like about a CO2 set up is the portability. I can hand carry the bottle to where it's needed. Plus it will run impact tools pretty easily.

So for me there are other uses for CO2 than just airing up tires.

I ran a 20lb co2 tank on my TJ when I had it. I could fill up my 37" tires from 8 psi to 25 about 9 or 10 times. Up here I can get it filled for ~$18. CO2 better than nitrogen because you get a high volume and pressure but the tank is not at high pressure so it's safer.

Thanks for the info, guys. Your experience is more like what I'm shooting for. $3 a fill is totally reasonable. I must have something going wrong, I'll dig into it this weekend.

10lb CO2 fills my 35x12.5x15 tires from 12-14 back to 25-26 psi 4 times (16 tires) with a little to spare... could probably push it to 5 times but I ran out after 18 tires (2 short of a set) once so I refill the tank after doing the set 4 times.

Great post and great information. I just ordered a 10lb CO2 tank for $85 free shipping and a regulator for $46 with shipping. It takes my onboard compressor about 3:30/ tire, or a bit more, and it's a lot of run time on my compressor. Although it's worked fine for several years, I thought $131 for a compressed gas system was reasonable.

That is why I have always used CO2, way faster than most compressors. I could fill my 37s in about one minute per tire.

For those looking for a system I really like the HyperFlow regulators, Wheelers Offroad sells them.

Fixed pressure [url]https://wheelersoffroad.com/i-25490058-hyperflo-150psi-non-adjustable-co2-regulator-reg150.html?ref=category:1345574[/url]
Adjustable pressure [url]https://wheelersoffroad.com/i-25490054-hyperflo-max-0-250psi-adjustable-co2-regulator-4130.html[/url]

Both work very well.

Fast is good... I've been contemplating adding a set of Monster Valves to my wheels. My 35s would air-down in 10-15 seconds and re-inflate in about 30 seconds.

[URL]https://powertank.com/apps/omega-search/?q=monster+valve#q=monster%20valve[/URL]

Just wondering, bear with me.

CO2 is probably a better choice for alloy wheels than steel wheels unless there is an absence of water vapor in the tire assembly as a whole which would be rare I would think. Water reacts with CO2 and creates carbonic acid which can/will attack the iron in the carbon steel. Though not the nature of hydrochloric or sulfuric acids, it is a corrosive just the same. Has anyone using CO2 noticed any above “normal” corrosion on the inside of their wheels, steel or alloy?

I've used CO2 for years, including on the same set of aluminum wheels for 8 or 9 years. Zero problems with corrosion or anything else. Had the tires balanced with the same Airsoft pellets all that time, and no issues with those, either.

39.5x16.5x17 Rockers on Cepek DC1s.

Mark

Great info guys!

@Spieg - those monster valves look pretty cool, I like that idea. However, the directions say you don't even need to derim. While I agree that you don't [I]need[/I] to, you will most certainly end up with chips in your tire when you drill and tap the rim. I have had loose machining chips rupture rubber diaphragms, albeit much thinner than a tire.

@Getaklu - I've been curious about that too. I once removed a bunch of air hose used as CO2 line in a grow and the hose had degraded in a way that I've never seen air hose with air in it degrade. I'll keep an eye out over the years after getting the CO2 going.

Another concern I have is freezing the regulator and hose, especially if the hose cracks. CO2 in the tank is stored as a liquid and vaporizes to come out, just like propane does. I have a lot of experience with drawing enough propane to freeze tanks (my fire sculptures can burn 600 lbs propane in a weekend!), so many of us fire artists heat our tanks. The 5lb in my experiment frosted up. For now I'll just roll with it and address it in the future if it becomes a problem, which I don't expect since PowerTank doesn't sell the PowerTank Heater.

So back to my failed experiment -> Eureka! I think the first 5lb fill was incomplete. I didn't weigh it, but the guy at Do Your Brew was like "I think I can fill it" then I got a second fill at Way To Grow and sure enough that filled the set of tires with more to spare. Great. The guys there also quoted me $7.50 out the door for a 20lb cylinder exchange, so I got one on Craigslist. 8 full sets of tires filled for $7.50 is totally reasonable.


Test fit the new mount for 20# CO2 cylinder:
[IMG]http://evanbeloni.com/4wd/xjbuildpics/2019_ojcga/cga_001.jpg[/IMG]


Before getting the second fill to test again, I tried the math route again because I need to prove this to myself and I'm a math and science dork. This time calculating the moles of CO2 required to fill the tires and comparing that to the mass inside a CO2 cylinder. This was pretty close to what you guys reported of 4 sets filled with a 10#! Great. Math:

[IMG]http://evanbeloni.com/4wd/xjbuildpics/2019_ojcga/cgamath_01.gif[/IMG]
[note the pressure in psig is gauge and pressure in Pascal is absolute]

[quote=SynergyXJ;329299]For now I'll just roll with it and address it in the future if it becomes a problem[/quote]

If you find yourself in need... Engine bay mounting for warmth? Find an old but usable tire heater from someone who used to race? Aftermarket automobile seat heater (James just put a couple in his jeep)?

I had my TJ for almost 10 years, I didn't see any corrosion issues on my aluminum wheels. It was a trailer queen the last few years so it saw less deflating and filling but it still had co2 in the tires.

No CO2 corrosion issues to report either but I have aluminum wheels and I run balancing beads. The beads keep everything pretty well polished inside.

To the question about Monster Valves, I believe they make 2 versions (or they did last time I checked). For one type you just drill and tap a hole without needing to remove the tire (although as you said, it might be a better idea to pull the tire to clean up the drill shavings). The other does require the tire to be removed because there is a retaining nut that needs to be installed inside the wheel (this is probably the style I would choose).

@Jim - Good idea with the tire heaters, I didn't know about those. I like that a blanket is part of it. I've used 12v flexible silicone heating pads with a foam backer/insulation before for propane in the jeep. Also thought about coiling copper tube around the exhaust because the CO2 is close, but then I have no control, just always hot. There's not enough room in engine bay, this sucker is pretty big.

@Spieg - Right on. I only see that one model that's just 1/4 NPT. Might try them out on the next set of tires since I'd be derimming anyway. Also depends on if they have lock-on chucks. I don't see any info about what you connect to it to inflate. And actually, looking closer it looks like deflating drains through those 4 jet holes, so that doesn't work with my CTIS, so nevermind, scratch that. Good looking out though, looks like a cool idea for most of us.