Nitrogen instead of compressed air

Nitrogen instead of compressed air

Author
Discussion

carl_w

6,707 posts

225 months

Wednesday 17th March
quotequote all
77racing said:
divers dry air expands less than compressor air usually
Yes, because compressor air has water vapour in it. I'm trying to understand your use of nitrogen vs divers' dry air. Surely for motorsport applications they are equivalent? Maybe if you're keeping the gas in the tyres for months there will be a difference.

leef44

2,316 posts

120 months

Wednesday 17th March
quotequote all
carl_w said:
I'm planning to run a 78% nitrogen, 21% oxygen and 0.9% argon mix this year.
I've looked at the various options and found this one to be the most economical.

77racing

Original Poster:

3,329 posts

154 months

Thursday 18th March
quotequote all
carl_w said:
Yes, because compressor air has water vapour in it. I'm trying to understand your use of nitrogen vs divers' dry air. Surely for motorsport applications they are equivalent? Maybe if you're keeping the gas in the tyres for months there will be a difference.
all tyres be it road or motorsport will contain water within the carcase of the tyre. nitrogen does not obsorb water molicules so thats why i went with nitrogen .Clearly some will not see the benifits and it is i think just a small advantage but all those small advantages add up to a few tenths a lap. who doln,t love a plastic trophy wink. as an aside divers air and nitrogen about the same price .

77racing

Original Poster:

3,329 posts

154 months

Thursday 18th March
quotequote all
leef44 said:
I've looked at the various options and found this one to be the most economical.
no one said motorsport was cheap and as i can afford to do some think different why not ? nitrogen is cheap to buy in my opinion, granted not as cheap as compressor air but thats not what i wanted to know.

Kawasicki

9,583 posts

202 months

Thursday 18th March
quotequote all
As a former tyre engineer all this talk of pure nitrogen offering clear benefits over dry air confuses me.

mmm-five

9,183 posts

251 months

Thursday 18th March
quotequote all
Kawasicki said:
As a former tyre engineer all this talk of pure nitrogen offering clear benefits over dry air confuses me.
Ooooh, you've gone and done it now!

The OP doesn't want to hear any dissenting opinions, even if they're scientifically valid.

rolleyes

77racing

Original Poster:

3,329 posts

154 months

Thursday 18th March
quotequote all
how,s that then ? have you got some think usefull to contribute ?

TimCrighton

995 posts

183 months

Thursday 18th March
quotequote all
The benefit for us is its easier to get hold of then divers air and its dry (which is the critical difference between whatever option you want and 'standard').

We've also found that it seems to remain marginally more consistent over long stints than divers air - perhaps a result of air absorbing moisture from the tyre carcass as it heats up? Perhaps its placebo.

liner33

8,672 posts

169 months

Thursday 18th March
quotequote all
TimCrighton said:
The benefit for us is its easier to get hold of then divers air and its dry (which is the critical difference between whatever option you want and 'standard').

We've also found that it seems to remain marginally more consistent over long stints than divers air - perhaps a result of air absorbing moisture from the tyre carcass as it heats up? Perhaps its placebo.
That was our thinking , also a dive cylinder is a useful and convenient source of compressed air for other uses at the track as we used air tanks for fuel and shifting and needed 140psi

BertBert

15,191 posts

178 months

Thursday 25th March
quotequote all
TimCrighton said:
We've also found that it seems to remain marginally more consistent over long stints than divers air - perhaps a result of air absorbing moisture from the tyre carcass as it heats up? Perhaps its placebo.
Can you elaborate about what consistency you see please and how you measure it?

And just for mechanical curiosity, how do you get rid of the air and replace it with nitrogen?

Evanivitch

10,127 posts

89 months

Thursday 25th March
quotequote all
If you're worried about consistency, then it's the moisture content that is really the big variable. Not the nitrogen content.

TimCrighton

995 posts

183 months

Tuesday 13th April
quotequote all
Sorry - slow reply to this one.

About 1 psi difference between Nitrogen and Divers air over a 20 minute on track period (one rising by 2psi, the other by 3psi) vs historically seeing rises of around 8-9 psi with normal compressed air. I'd suggest though every scenario will be different and it will be important to look at whether you have purged properly, what moisture content was in the tyres etc etc.

No doubt it could be argued the on track conditions weren't quite the same on the comparable sessions between Nitrogen and Divers air, although the weather was broadly the same and the times were very very similar so its as good a back to back as we ever achieved. After than point I think you are dreaming at least well beyond the tolerance of the average decent tyre gauge and mechanic!

Tyres had beads broken and were resealed to the rim with Nitrogen / Divers Air in that scenario.

As said the key is to get moisture content out and ensure whatever is in the tyre is as dry as possible

944 Man

524 posts

99 months

Monday 19th April
quotequote all
carl_w said:
I'm planning to run a 78% nitrogen, 21% oxygen and 0.9% argon mix this year.
Works for me. I have an endless supply.

Kawasicki

9,583 posts

202 months

Monday 19th April
quotequote all
TimCrighton said:
Sorry - slow reply to this one.

About 1 psi difference between Nitrogen and Divers air over a 20 minute on track period (one rising by 2psi, the other by 3psi) vs historically seeing rises of around 8-9 psi with normal compressed air. I'd suggest though every scenario will be different and it will be important to look at whether you have purged properly, what moisture content was in the tyres etc etc.

No doubt it could be argued the on track conditions weren't quite the same on the comparable sessions between Nitrogen and Divers air, although the weather was broadly the same and the times were very very similar so its as good a back to back as we ever achieved. After than point I think you are dreaming at least well beyond the tolerance of the average decent tyre gauge and mechanic!

Tyres had beads broken and were resealed to the rim with Nitrogen / Divers Air in that scenario.

As said the key is to get moisture content out and ensure whatever is in the tyre is as dry as possible
Are you sure? A 2 or 3 psi rise from cold to hot with nitrogen/dry air seems very low... and 3 or 4 times that with normal air seems a huge difference. Are you sure?

Cliffe60

1,189 posts

3 months

Thursday 29th April
quotequote all
Entirely depends on how much water there is in your normal air source. There is no discernable difference between the rate of expansion of oxygen and nitrogen.
However liquid water will occupy 1600x the volume when it turns to vapour, so a small amount will cause a big rise in pressure as the tyres heat up.
A completely dry pure air source will expand at the same rate as nitrogen.

Tcars01

14 posts

160 months

Tuesday 6th July
quotequote all
also switching to Nitrogen for my next race meeting, just a quick question.

I have new tyres fitted at the track and they're filled with just normal compressed air as expected by the tyre supplier. I obviously need to try and purge that out to refill but what do you do to fully expel the compressed air? I am guessing simply opening the valve until done and refilling with the Nitrogen won't do the job well enough, or will it? Or is there a vacuum pump or something recommended to get everything out properly? This is all new to me.

Thanks

Cliffe60

1,189 posts

3 months

Tuesday 6th July
quotequote all
leef44 said:
carl_w said:
I'm planning to run a 78% nitrogen, 21% oxygen and 0.9% argon mix this year.
I've looked at the various options and found this one to be the most economical.
Funnily enough, that’s the mix I’m planning to breath for the next year!

Kawasicki

9,583 posts

202 months

Tuesday 6th July
quotequote all
Tcars01 said:
also switching to Nitrogen for my next race meeting, just a quick question.

I have new tyres fitted at the track and they're filled with just normal compressed air as expected by the tyre supplier. I obviously need to try and purge that out to refill but what do you do to fully expel the compressed air? I am guessing simply opening the valve until done and refilling with the Nitrogen won't do the job well enough, or will it? Or is there a vacuum pump or something recommended to get everything out properly? This is all new to me.

Thanks
You fit the tyres underwater, so the cavity is completely filled with water. Then you inflate with the nitrogen, which purges out the water.

liner33

8,672 posts

169 months

Tuesday 6th July
quotequote all
Kawasicki said:
You fit the tyres underwater, so the cavity is completely filled with water. Then you inflate with the nitrogen, which purges out the water.
No you do it in a vacuum chamber, you just need to hold your breath while you do it

Kawasicki

9,583 posts

202 months

Tuesday 6th July
quotequote all
liner33 said:
Kawasicki said:
You fit the tyres underwater, so the cavity is completely filled with water. Then you inflate with the nitrogen, which purges out the water.
No you do it in a vacuum chamber, you just need to hold your breath while you do it
Whatever you do, don`t fart.