Inflation Chart

[junkie_ball]

A quick question have searched the net and found numerous answers on this one. I may have missed a chart somewhere (hopefully).

After a ride with lots of punchers i decided to go the route of a co2 inflator to get me out of trouble (Will still use my mini pump if i'm not in a hurry) i have been looking for a chart to see what pressures various size canisters will inflate too. I ride 700x25c tyres and have seen 16g canister pressure ranging from 90 psi to 130 psi. if they inflate to 130psi using a complete canister would over inflate my tyre as they are only rated to 120 psi max so would appreciate if anyone could point me in the right direction.

Thanks

 

[sevenfourate]

Seller on ebay has some info here:

http://www.ebay.co.uk/itm/281719364743?_trksid=p2055119.m1438.l2649&ssPageName=STRK:MEBIDX:IT

 

[Ern1e]

Speaking from working in the tyre industry firstly no gauge is ever 100% accurate and most tyres will happily stand at least a 10% increase in pressure so that would make it 132 psi. Once you have got back home or to a air pump I feel sure things would be ok. I do remeber a member of staff fitting some continetal folding bead tyres to his bike wacked the pump on and inflated the things to 140 psi to seat the beads which was 20 psi over what we used to put in truck tyres lol.

 

[classic33]

Speaking from working in the tyre industry firstly no gauge is ever 100% accurate and most tyres will happily stand at least a 10% increase in pressure so that would make it 132 psi. Once you have got back home or to a air pump I feel sure things would be ok. I do remeber a member of staff fitting some continetal folding bead tyres to his bike wacked the pump on and inflated the things to 140 psi to seat the beads which was 20 psi over what we used to put in truck tyres lol.

You inflated truck tyres to 120 PSI!!
Higher volume & a lower pressure normally.

 

[Deleted member 23692]

here you go - http://genuineinnovations.com/co2chart/

 

[Milkfloat]

I don't think any of the cartridges or tube combinations will allow perfect assessment of the psi you will be putting in, let alone allowing for loss from the valve when trying to get the air in. I use my co2 as a get me home or on my way method and my gauge is a pinch between my finger and thumb. You don't have to use all the air in one canister. I do carry two canisters in case of multiple flats or a cock up.

 

[martint235]

The canisters I use go to 130psi as I used to run Lelly's tyres at 145 usually. However I now have 25s on both bikes with a max of 115psi but I don't think the canister will over-inflate them or at least I've never had any issues yet with just connecting the canister, pulling the trigger and waiting till it stops.

 

[Ern1e]

You inflated truck tyres to 120 PSI!!
Higher volume & a lower pressure normally.

On the odd occasion we had to go way above that to seat the beads ! this is one of the many good reasons we used to put them in a cage just in case, at one time I had a trainee who for want of a better way of putting it was bl**dy dumb and would not listen so I borrowed a dummy hand grenade from the TA. took that into work shoved it in his grimy little mitt pulled the pin out saying to him "now f**k with that" his face was a picture ! So when you are sat next to an 285/85 x 22.5 truck tyre which should be operating at anywhere between 90/120 psi is and doe's have the explosive force as per a grenade. If you have had the misfortune to see one going off on the road it can cause some serious damage to what ever gets in its way !

 

[SpokeyDokey]

A quick question have searched the net and found numerous answers on this one. I may have missed a chart somewhere (hopefully).

After a ride with lots of punchers i decided to go the route of a co2 inflator to get me out of trouble (Will still use my mini pump if i'm not in a hurry) i have been looking for a chart to see what pressures various size canisters will inflate too. I ride 700x25c tyres and have seen 16g canister pressure ranging from 90 psi to 130 psi. if they inflate to 130psi using a complete canister would over inflate my tyre as they are only rated to 120 psi max so would appreciate if anyone could point me in the right direction.

Thanks

Sod the tyre pressures, I'd just hit the buggers straight back.

 

[junkie_ball]

here you go - http://genuineinnovations.com/co2chart/

Thanks for the chart but is it just me any charts i have seen including the one in your link doesn't include a 700x25 tyre. Is this not strange as most road bikes nowadays seem to use these now. I know i can do the maths but surely there must be a comprehensive chart somewhere.

My main concern was over inflating and blowing a tyre on the side of the road as i would always double check pressure on the return home after having a puncture.

 

[Tim Hall]

There's clever SCIENCE and HARD SUMS that you can do, involving the mass of gas, which we know (12g or 16g) the atomic weight (?) of CO2, which we can calculate and the volume of the inner tube, which we can also calculate ( (πr^2)(2πR), where r is the radius of the tube and R is the radius of the wheel). Add in Avagadro's number (6.02 x 10^23), do some long since forgotten calculation (A level chemistry was a few years ago), fiddle around with the units, and, shazzam, the theoretical pressure in various sized inner tubes is known.

 

[Tim Hall]

Right I've done some sums.

Assuming the tube is a torus centred around the radius which is half the bead seat diameter plus half the nominal tyre size, the volumes of various tyre sizes are:
23mm 0.84l
25mm 1.00l
28mm 1.25l

A 16g gas bottle, molecular weight 44 (c=12, O=16) has 16/44 = 0.36 mol of gas. At STP this has a volume of 22.4l. So squeezing 22.4l into the various volumes above gives the following (theoretical) pressures:
23mm 140psi
25mm 118psi
28mm 94psi

Can anyone who actually knows this stuff check my workings?

 

[Globalti]

On truck tyres, a few years ago a woman passenger in a car was killed when a car tyre, which she was carrying on her lap (!) exploded.

http://news.bbc.co.uk/1/hi/scotland/edinburgh_and_east/8600833.stm

 

[cisamcgu]

Right I've done some sums.

Assuming the tube is a torus centred around the radius which is half the bead seat diameter plus half the nominal tyre size, the volumes of various tyre sizes are:
23mm 0.84l
25mm 1.00l
28mm 1.25l

A 16g gas bottle, molecular weight 44 (c=12, O=16) has 16/44 = 0.36 mol of gas. At STP this has a volume of 22.4l. So squeezing 22.4l into the various volumes above gives the following (theoretical) pressures:
23mm 140psi
25mm 118psi
28mm 94psi

Can anyone who actually knows this stuff check my workings?

Internal radius = 0.622/2 = 0.311m
External radius = 0.627/2 = 0.314

Volume = 1/4 x (pi)squared x (a+b) x (b-a)squared

V=1/4*3.14*3.14(.311+.314)*(0.314-0.311)*(0.314-0.311) = 0.14l

But this is very old maths - I may well be wrong and the external radius looks wrong anyway ....

 

[biking_fox]

Right I've done some sums.

Assuming the tube is a torus centred around the radius which is half the bead seat diameter plus half the nominal tyre size, the volumes of various tyre sizes are:
23mm 0.84l
25mm 1.00l
28mm 1.25l

A 16g gas bottle, molecular weight 44 (c=12, O=16) has 16/44 = 0.36 mol of gas. At STP this has a volume of 22.4l. So squeezing 22.4l into the various volumes above gives the following (theoretical) pressures:
23mm 140psi
25mm 118psi
28mm 94psi

Can anyone who actually knows this stuff check my workings?

There's probably an issue with how much comes out/remains in the canister. It's internal volume will be a notable increase in the tyre volume. But he chemistry seems about right.