Sphere shelf life

juraj · Post by **juraj** » 15 Apr 2008, 12:13

Hi All

I know spheres over time loose their charge of nitrogen via the membrane, I know this happens to new spheres just sitting on the shelf. Of course fitted spheres work a lot harder the charge is compressed to much higher pressures when the hydraulic system is working.

Anyway does any one have any experience with old new spheres? Fitted spheres tend to last at most about 3 years, probably by year 2 end they are already getting quite hard. But what about 3 year old new spheres how do they compare.

There is a set of new spheres on ebay that i think is about 5 years old. I am wondering how charged up they still would be. Is 5 years trivial? Is 10-15 more of a concern?

Anyway this is more rhetorical as I bet the difference in the final price and that of new spheres will be about £10-£20.

bye all

ellevie · Post by **ellevie** » 15 Apr 2008, 17:23

I cant remember the exact details now but I've used some "new old stock" genuine Citroen spheres with no problems.

juraj · Post by **juraj** » 15 Apr 2008, 17:26

thanks

yeh that does sound right

thinking about it, id say the depletion of nitrogen on the shelf would be only minimal, theoretical,

bye

Post by **elma** » 15 Apr 2008, 23:11

Nitrogen @50Bar of pressure @ rm temp will diffuse through the membrane, albeit very slowly.

W/o a test being done couldn't say how much.

I personally refuse to buy any which were gassed more than 3 months prior to purchase and always make sure that the strut pairs were gassed on the same day. I'm a scientist though and you all know we are obsessive.

I'd like to have a bottle of nitrogen and those valves on the sphere nipples so that I could make all the pressures correct.

I know that thickness of LHM in winter is blamed for handling changes but in my mind it's also because the pressure of the nitrogen reduces and ideally I think we should all pump them up when that happens.