Helium for tyres.

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I don't think that this table of seal leak rates applies to gas diffusion through rubber.

The hydrogen number is a good example -- it's only 2x that of nitrogen. Hydrogen is very good at diffusion through "impermeable" barriers, sometimes many orders of faster than other gases.
 
Originally Posted By: djb
I don't think that this table of seal leak rates applies to gas diffusion through rubber.

The hydrogen number is a good example -- it's only 2x that of nitrogen. Hydrogen is very good at diffusion through "impermeable" barriers, sometimes many orders of faster than other gases.


I would agree. Compare a helium filled balloon to one filled with air, and see which runs out first. The chart shows them as very close, but in a balloon, the helium filled one will deflate much more rapidly.

It appears this company makes metal seals. Ordinarily, helium's diffusion rate (being monatomic) is about three times that of normal air. Hydrogen will penetrate even faster.
 
Originally Posted By: Garak
Originally Posted By: djb
I don't think that this table of seal leak rates applies to gas diffusion through rubber.

The hydrogen number is a good example -- it's only 2x that of nitrogen. Hydrogen is very good at diffusion through "impermeable" barriers, sometimes many orders of faster than other gases.


I would agree. Compare a helium filled balloon to one filled with air, and see which runs out first. The chart shows them as very close, but in a balloon, the helium filled one will deflate much more rapidly.

It appears this company makes metal seals. Ordinarily, helium's diffusion rate (being monatomic) is about three times that of normal air. Hydrogen will penetrate even faster.


look at the last table then wrt molecular diffusion.
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Originally Posted By: Garak
Ordinarily, helium's diffusion rate (being monatomic) is about three times that of normal air. Hydrogen will penetrate even faster.


That's not a logical statement, as hydrogen is diatomic.
 
Originally Posted By: Shannow
Originally Posted By: Garak
Ordinarily, helium's diffusion rate (being monatomic) is about three times that of normal air. Hydrogen will penetrate even faster.


That's not a logical statement, as hydrogen is diatomic.


Yes, and helium is monatomic. Helium diffuses through such a membrane at about 65% the rate of hydrogen. Hydrogen diffuses slightly faster than helium, partially due to lower mass. The molecular radius of H2 is smaller than the van der Waals' radius of He.
 
I use CO2 to air up my Tacoma tires after off road excursions and have not noticed any difference.
 
Originally Posted By: Papa Bear
Should use water to fill tires, it would be so easy to find the leaks ....


LOL
 
Originally Posted By: Jason2007
Running helium in your tires will cause them to squeal in a much higher octive.


lol
 
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