Equinox

I used my CO2 pump today and it worked great. It came with a 16 gram cartridge, but when I went to Wally World, they only had 12 gram cartridges. What would happen if I piggy-backed two 12g cartridges?
Would I pop the tube?

Mentor58

one of the companies that make inflators and combo pump/inflators has a page that lays out what kind of pressure you get from different cartridges with different sized tires. I'm sure somebody will post it, I'm brain dead on the name of the firm right now.

Steve W.

Mariner Fan

I've been looking at these things for along time and really don't know much. Any advice on a particular brand or style would be great. So does a 16 gram bottle fill a 23c tire? Is it a one time shot?

MrCjolsen

No it will not pop your tube. The pressure in the CO2 cartrige is about 90-100 PSI. It's the volume that is the variable.

carlson5200

I just picked up a CO2 filler thinger, and I have one thought on it (haven't used it yet by the way). Why not add a built in relief valve that is adjustable to whatever you want tire pressure set to. In other words, just dial it to 110psi and pull the trigger. Once 110 is reached the remaining CO2 can simply be discharged or kept for later - no over / under inflation, no bulky gage to carry. If I was smarter and not so lazy I might even try to figure this out, like a prototype or something.

Mentor58

The company I was thinking about is Genuine Innovations. I've heard a LOT of good stuff about them, thinking about getting one. I especially like the idea of being able to use it as a mini pump to check that I don't have a pinched tube, check for where the leak is when reduced to patching the old tube.

Steve W.

Mariner Fan

So you basically use the CO2 inflator and pinch the tire to figure out how much air you have? Most folks in the forum say the CO2 inflator is the way to go vs a hand pump.

thewalrus

It wouldn't be a good idea to put two 12g cartridges in a 700x23 tire with any tube - you'd end up way above 160psi and most likely shred the bead.

timhines

yeah one 12g cartridge should do one 700x23c tire/tube.

genuine innovations has a good product. I've bought 3 of theirs.

steppinthefunk 

Most 12gram Co2 cartridges are non threaded - They will not work on a threaded Co2 adapter...

chroot

If you're using normal road bike tires (typically inflated to 100+ psi), don't even worry about. Just open the cartridge and let it fill the tire until no more gas is moving. Your tire will be at about 90-100 psi, as this is the maximum pressure obtainable from a CO2 cartridge.

- Warren

fsor

On 700cX23 tires I only get about 95-100psi out of a 12g cartridge. Since I need more psi, I use a 16gm.....that is about 125# or 130. I have never popped a tube with 16g. The 12g will get me home but I have pinchflatted at the lower pressure. The people with the little combo pump/CO2 inflator use the 12 g cartridges and just pump 20-30psi in first by hand.....this is a cool idea as the 12g unthreaded cartridges can be bought very cheaply in bulk.

Elvish Legion

There are a number of adapters that can take either threaded or non, so this is not an issue

GrannyGear

Idiot question...does CO2 have thinner molecules that leak thru tubes faster?. It seems every time I use one my tire has significantly deflated by the next morning.

inkdwheels

Im not sure on the reason why, but the air will escape faster. If i have to use a co2 cartridge to get home, normally i'll let all of it out and use my track pump to brimg it back to the correct pressure before my next ride.

steppinthefunk 

I stand corrected...

Stealthman_1

I haven't measured the molecules myself... , but your experience is not unique...Do the WallyWorld 12gers unless you are over 210 or so.

snoboard2

it'd make more sense for normal air to leak out faster seeing that N is alot smaller than CO2. i love my co2 only had to use it once, fast and no pumping. of course i went home and filled it the rest of the way, i hate having my tires below max.

Team Hammertime

Air: 70 percent Nitrogen, 16 oxygen , rest ( i think close enough)

oxygen molecule is O=O
carbon dioxide is O=C=O

Though the three-D structure is diffrent for co2 and oxygen, co2 is still larger because of the extra carbon atom.

and i dont believe nitrogen bonds with itself, instead just stays N, though even N=N would be smaller than co2.

Of course there are many different molecules in the air including ones with nitrogen and oxygen, but i think they wouldnt make a large enough difference.

It has been awhile since I took bio so correct me if i am wrong.

By the way please dont correct my grammar or spelling please because:
Did you konw taht the hmaun mnid is a birllnat mcahnie. I bet ervyenoe who is rdaenig **** has zreo porbelm uednrentsaing waht is bineg siad. It is pvoren taht you olny msut sepll the frsit and lsat lteetrs crorcet for the biran to udnresantd lgnagaue. Yuor biran flils in the rset. Azmaing!

**** psot is tchneiclaly cmpoetle dibrlbe, and you sitll get it. So raelx, oaky? I cnnaot wiat utinl you gmamarr nzais ctriquie **** psot. How fsat did you raed **** praagparh?

inkdwheels

Holy crap. I just read that as easily as anything else. That settles it, im never using spell check again.

Trsnrtr

So, pump the thing up like you're supposed to do before every ride and everything will be copacetic.

DannoXYZ 

Uh... where did you get that info? In order for flow to occur, you have to have a pressure-differential. If there's only 90-100psi in a cartridge, how does it ever get up to 120psi with a 16gm cartridge; wouldn't it stop when the pressure in the tyre reaches 90-100psi and equalizes with the cartridge? How does the 2nd 12gm cartridge raise pressure to 130-140psi?

Simple way to calculate pressure in the cartridge, just plug into ratio of PV=nRT. At STP, 12gm of CO2 occupies about 6 liters. Stuff that into the 0.015 liter volume of of a cartridge and you can figure out how much pressure's in there..

aerodave

Nitrogen does form a bond with itself, and makes N2. Even though nitrogen atoms are smaller than oxygen atoms, an N2 molecule is bigger than an O2 molecule. It's all about the strength of the bond. Tires pumped with pure nitrogen will leak less quickly than an 80-20 mixture of N2 and O2 (which is air).

I believe CO2 molecules are even bigger than nitrogen, but don't quote me on that. I've also heard that CO2 leaks out worse than regular air.

aerodave

That's true. Bt to figure out the final pumping pressure, you'd need to figure out what pressure 12g of CO2 would be when it takes up the combined volume of the tube and cartridge. It will be lower than the pressure that's intially in the cartridge, since the cratride will lose significant pressure as it fills up the tube. When the tire stops filling they're at a new equilibruim pressure.

My guess is that the cartridge is initially at WAY higher than 90 psi. It it started at 90, you'd probably only be able to get the tube to fill to about 30 psi as the cartridge is emptied. If you want your equilibrium pressure to be around 90, you'll have to start with a LOT of pressure in the cartridge.

KingTermite 

Very ironic....I was just a bike shop yesteday and decided to get some new cartridges as I was out. Mine takes 12 gram cartridges, but all they had were 16 gram cartridges.

I think the CO2 pumps equalize at the right pressue and won't let you put more in anyway...so you should be fine.