...and another thing

[Chassis 33]

I was talking to a few chaps over the weekend and the issue of nitrogen filling tyres was mentioned. Basically you can get your tyres filled with nitrogen when they're fitted but struggle to top up at the circuit etc.
I work in high pressure gas and hydraulics, is it worth me looking into the cost of pressurised gas bottles, either a group buy of a small unit, say 6l x 250bar or a larger one that can be shared about?

I reckon 6lx250bar is enough to fill around 26 18" tyres from flat to 25psi, obviously more if you're just topping up.
Regards
Iain

[teamHOLDENracing]

or just rent cylinders and buy nitrogen from Air Products or BoC...

[Chassis 33]

Thats the other route, its something like £50/yr for bottle, sounds like you've been down that route - not sure what BOC or Air Products charge for regulators or how much per nitorgen charge. Any ideas?

Regards
Iain

[profstoff]

teamHOLDENracing said:

or just rent cylinders and buy nitrogen from Air Products or BoC...

EFA

Wash your mouth out Andy!!!

[Jetblackonetenth]

Just check that the tyre fitters are happy to remove tyres filled with nitrogen.

I also believe that in order to get the benefit you have to completely remove all the air

[Chassis 33]

I'd imagine if your local tame tyre fitter was prepared to fill with nitrogen they'd be able to dismount nitrogen filled tyres too.
Regards
Iain

[teamHOLDENracing]

I use nitrogen for my air jacks, and I have a regulator with a tyre filling adaptor to use on tyres if I wish. In practice I've only used it in my tyres once. On that occasion I rigged up an extraction system to purge the air out of the tyres before filling with nitrogen. I used an air compressor driven fluid extractor connected to the tyre valve to suck all the air out of the tyre until it collapsed in on itself. It took a very long time per tyre and it isn't something I could do at a circuit if I'd just had new tyres fitted.

I can't say I found any great benefit on track despite all this effort - I naively thought the pressures wouldn't move at all with temperature, which is of course nonsense. You still have to set the pressures cold quite a bit below where you want them hot.

I only went through the whole rigmarole once....

[Graham]

I've spoken to quite a few people who have tried it, and all have gone back to using normal compressed air.. too much faffing around for not much benifit.. As Andy says you still need to set hot and cold try temps..

[Chassis 33]

The advantage comes be removing the moisture content, even using an inline dryer compressed air has a variable moisture content that is difficult to measure. By using high purity nitrogen you're removing a variable, but are still held by the contraints of physics, ie pv/t= "a constant" and so on, so you obviously still have to set hot and cold pressures etc., remember not all substances expand with temperature, water being the obvious example.

If you're running in other series its worth carefully checking the regs as some series insist you use "air" and check this in scrutineering, obviously there are ways around this to ensure you have virtually dry "air".

Anyway those who are interested thank you for contacting me, those who obviously aren't need not post any further!

Regards
Iain

[NTEL]

Chassis 33 said:

remember not all substances expand with temperature, water being the obvious example.

Regards
Iain

Errrr.......water does expand with temperature matey

[Chassis 33]

...why does ice float?
Regards
Iain

[NTEL]

Water is at its most dense when at 4 deg C. Either side of that it becomes less dense and therefore expands blah blah blah.

[Chassis 33]

Next you'll be telling me we should use NTC materials to counteract the expansion of the normal gas in you're tyres!!!

Regards
Iain

[teamHOLDENracing]

If you have your own gas bottles will you actually be able to find anyone to fill them for you?

[Chassis 33]

Any accumulator manufacturer or distributor will fill 'precharge' a bottle for a small fee. As i work for one such manufacturer I get it for free and would just need to cover the cost of the initial kit. Anyway Andy I thought you had a supplier and weren't interested?
Regards
Iain

[teamHOLDENracing]

I'm not Iain. It was however a genuine question about filling bottles.

[sarbec]

NTEL said:

Chassis 33 said:

remember not all substances expand with temperature, water being the obvious example.

Regards
Iain

Errrr.......water does expand with temperature matey

THATS WHY IT SPLITS ENGINE BLOCKS WHEN NO ANTI FREEZE IS FITTED

[profstoff]

sarbec said:

NTEL said:

Chassis 33 said:

remember not all substances expand with temperature, water being the obvious example.

Regards
Iain

Errrr.......water does expand with temperature matey

THATS WHY IT SPLITS ENGINE BLOCKS WHEN NO ANTI FREEZE IS FITTED

Water expands as it freezes, ice at 0 deg C, is bigger than water at 0 deg C, hence your cast iron block (which does not have a lot of ductility) cracks. After it's done its damage, it will contract with lowering temperature like any other solid.