Topping up da toobs

[Limey Linda]

Has anyone used a CO2 for topping up the tubes. I have a few paintbal gun cylinders that I can refill from a large tank at home. Any comments would be welcome. I know you cannot do it too fast without freezing.
Thanks

[keelhauled]

Often did it from dive bottle, just keep the jet about 3 inches from the valve then when the tube gets hard the pressure equalizes and valve lets no more in. The only thing about CO2 is the fact that it becomes a weak acid when disolved with any salt water that may be in the tubes, so may rot the tubes from the inside.

[Limey Linda]

Originally Posted by keelhauled

Often did it from dive bottle, just keep the jet about 3 inches from the valve then when the tube gets hard the pressure equalizes and valve lets no more in. The only thing about CO2 is the fact that it becomes a weak acid when disolved with any salt water that may be in the tubes, so may rot the tubes from the inside.

That is could to know, thanks. I assume there would no problems using nitrogen.

[Tim M]

I don't see why not - afterall liferafts are filled with CO2 very quickly.

[Cookee]

Originally Posted by Limey Linda

That is could to know, thanks. I assume there would no problems using nitrogen.

I seem to remember that nitrogen is preferred as it is less likely to leak (bigger molecules or something) and expands less in heat - might be wrong though! I think they might fill tyres with it as well for a similar reason?

[Nos4r2]

Originally Posted by Cookee

I seem to remember that nitrogen is preferred as it is less likely to leak (bigger molecules or something) and expands less in heat - might be wrong though! I think they might fill tyres with it as well for a similar reason?

Someone on Iboats.com forums suggested filling the tubes with nitrogen for exactly that reason-apparently it's common in the USA to fill tyres with it.

Originally Posted by Tim M

I don't see why not - afterall liferafts are filled with CO2 very quickly

Not sure the comparison to liferafts really counts though-they aren't left inflated for years at a time. It's an interesting question though.

[Pete7]

Originally Posted by Nos4r2

Someone on Iboats.com forums suggested filling the tubes with nitrogen for exactly that reason-apparently it's common in the USA to fill tyres with it.

Surely our tubes have 79% Nitrogen in them anyway?

Pete

[BassBoy]

Hows about hydrogen! The positive bouyancy must reduce fuel consumption! Maybe thats what they use in them french ribs?


Seriously though........what about helium? Anyone done any experiments? Very expensive though.

[Pete7]

Helium costs about 1p per litre, now work out how many litres you would need to fill your tubes. The other problem is helium is a very light gas and would leak out past valve seals and through the material seams.

Oddly enough ordinary air seems to be quite a cost effective solution

Pete

[BassBoy]

Cheaper than I thought!

My question was really...... has anyone ever tried it?.
I'm sure some crazy naval architect has had access to the required seaming/valve technology and budget to give it a go.