refilling suspension spheres

andmcit · Unread post by **andmcit** » 08 Sep 2006, 21:19

nigelc116 wrote:What would happen if you refilled them with air, most people have a compressor nowadays.

I'm not a scientist, and never got on in Physics/Chemistry at school

but this sounds like a recipe for disaster!

I believe the whole idea is to use ANY inert gas, ANYTHING but Oxygen -
doesn't Oxygen (especially pure Oxygen!) go all explosive on you when
you're handling it/compressing it or sending sparks around it...

...that's the whole point of it being Oxygen Free!

I guess I could try my Oxygen free Argoshield Mig welding gas at a push!

Andrew

Unread post by **philhoward** » 08 Sep 2006, 21:20

Amtek are another brand which appeared after the Citroen monopoly on Spheres ran out (was is a patent?) and other companies jumped on the aftermarket bandwagon

Mandrake · Unread post by **Mandrake** » 08 Sep 2006, 21:24

reddeathdrinker wrote:Sphere's aren't that expensive, are they?

A set of 6 comes in at under £150, with the reassurance of a guarantee....

They might be dirt cheap for you fellas in the UK, but they're bloody expensive here in New Zealand. (and Australia)

I just had to buy two new rear spheres for my Xantia, they cost me $178 plus tax EACH. (Thats about £70 plus tax) Thats genuine Citroen ones mind, as 3rd party ones aren't available over here as far as I know.

(And that doesn't even take into account that numerically, NZ wages are MUCH lower than UK wages, as the general cost of living is also lower, making the sphere prices even more out of proportion)

Shipping over GSF spheres isn't really an option, as the shipping costs mean you have to buy at least 4 sphere at a time before you break even with the New Zealand prices due to the high shipping cost of heavy objects like spheres, and even then you're getting 3rd party types not Citroen ones...

It makes a lot of sense to regas when they cost that much, and a few years ago my Dad had a regassing rig and did all the spheres for our GS's and CX we had at the time.

Unfortunately we don't have that rig any more and a guy that used to regas spheres that we knew has gone to ground so I was forced to buy new....

I also agree about regased spheres lasting fine - the key is to regas early and often. If you keep their pressure up to at least 70% of normal they can last almost indefinately.

Rule of thumb is not to bother regassing a sphere which has been operated on a car at less than half its normal pressure. On the other hand a sphere sitting on a shelf for years which is low in gas can be regased reliably before use because the diaphram has not been subject to flexing.

The damage comes from allowing the sphere to be operated on the car with a very low pressure - which causes excessive flexing and folding of the diaphram leading to eventual cracking and failure.

Regards,
Simon

Unread post by **philhoward** » 08 Sep 2006, 21:27

Long shot, I know.........but Rolls Royce spheres are virtually identical. Not sure if this will help, but might be another avenue to explore!

citronut · Unread post by **citronut** » 08 Sep 2006, 22:23

john alexander wrote:Hi I recently posted an enquiry on the the use of westroen spheres , for whatever reason this post never appeared. I just replaced the rears on my xantia 1.9 td estate with GSF ones but can see very little difference in ride quality . Who are amtek???. at least I 've heard of AL-KO . Westroen 6 for £150 worth a go . regards john.

if you see very little difernce then you might have somthing elss wrong,like maybe siezed or partly siezed hight corector linkage
regards malcolm

AndersDK · Unread post by **AndersDK** » 08 Sep 2006, 22:40

nigelc116 wrote:What would happen if you refilled them with air, most people have a compressor nowadays.

Air is not just air.
Atmospheric air as we breathe it - is a mix of many gasses and vapours - including water.
Besides even the best home compressor wont take you up to more than some 8bars.

The rear suspension spheres most types starts at an inflation of 35bars, while most front sphere typess are inflated to 55bars. The accumulator spheres are inflated to 62bars.

I wouldnt like to have a homemade modified air compressor capable of such pressures as a neighbour sleeping in my garage ...

Probem is not to refill with Nitrogen. Nitrogen as an industrial product very cheap and ready available all over the world. Problem is the industrial standard flask the gas comes in - these are rather expensive - and so is the filler fittings capable of handling the max safety pressure of 200bars on such industrial flasks ...

DoubleChevron · Unread post by **DoubleChevron** » 09 Sep 2006, 00:29

nigelc116 wrote:What would happen if you refilled them with air, most people have a compressor nowadays.

It's not only you need nitrogen... But I've never seen a compressor that'll go upto 75bar

That's 75bar, not 75psi

seeya,
Shane L.

slim123 · Unread post by **slim123** » 09 Sep 2006, 09:39

Air aint an option, as the air from your compressor contains oxygen, this will cause rust on the inside.

Spheres are filled with Nitrogen (Oxygen free)

The other point is that a good compressor will get you about 200psi max. On the Xantia, front spheres are filled to 55 bar, rears are 30bar, main accumulator 62 bar and the anti sink 50 bar.

One bar of pressure is more or less 14 psi (70 bar = 1000 psi) you can work out the math yourself, when you do you will find out that you aint gonna get enough pressure.

Regards
Slim

406 V6 · Unread post by **406 V6** » 09 Sep 2006, 10:13

You guys seem to be forgetting that nitrogen virtually doesn't increase it's volume with temperature (well, our cars working temp range), being stable. ones,

jeremy · Unread post by **jeremy** » 09 Sep 2006, 10:42

Within limits (by which I mean they are in the gaseous phase) most gasses have a close approximation to the theoretical ideal gas - and will behave in the same manner physically.

Chemically things are a bit different - Oxygen is chemically very active and so will be avoided for most practical applications - and things like Nitrogen, Carbon Dioxide, are virtually inert for most purposes, cheap and convenient. The truly inert gasses (Argon, Crypton, Neon atc) are also available relatively cheaply but are no better than Nitrogen for sphere gassing.

Of course things are different at welding temperatures - Carbon Dioxide will react a bit - and de-compose, Nitrogen presumably will do the same but more so - and so is not used. The inert gasses -reamin - inert of course.

Besides chemical purity - making sure there ia no water vapour in the gas used will be important.

ellevie · Unread post by **ellevie** » 09 Sep 2006, 12:26

As a matter of interest, there is a 2000 psi (>136 bar) air compressor on eBay at the moment for £125.
Just search for psi compressor.

Clogzz · Unread post by **Clogzz** » 09 Sep 2006, 14:39

Rolls Royce spheres are virtually identical.

The Rolls Royce sphere has a different thread.
The local Citroën stealer does Bentley too.
Many Bentley owners have bought the car when they could afford it, but are retired now.
There are also quite a few inherited ones, and the inheritors are just about compelled to keep them for now in the hope that their value will rise in time.
They get an engineering mob to make an intermediate threading piece to adapt the Citroën spheres.
Citroën spheres here, opening special: about £70.
Rolls Royce spheres: £320 a piece.

KP · Unread post by KP » 09 Sep 2006, 16:48

How does one re-fill the spheres while fitted to the car as i would think they would need to come off to be done??

May get the rears and accumulator by Westroen just to save me the hassle for £5 extra a peice saves me crawling under the rear of the car for fun.

slim123 · Unread post by **slim123** » 09 Sep 2006, 16:49

The Rolls Royce sphere is the same as the Citroen on except for there is no damper in the neck and the pressures are different.

Rear suspension = Large (500cc) sphere 18.5 bar pressure

Main Accumulators = Small (400cc) sphere 75 bar pressure.

The reason for the 75 bar in the accumulators was because at 62 bar the cars were not getting out of warranty with a decent pressure left in, as the regulators on a Rolls Royce are mounted under the exhaust manifold and run very hot, thus diffusion is quicker.

But the threads are the same as they are standard Citroen spheres.

Regards
Slim

AndersDK · Unread post by **AndersDK** » 09 Sep 2006, 18:28

KP wrote:How does one re-fill the spheres while fitted to the car as i would think they would need to come off to be done??

May get the rears and accumulator by Westroen just to save me the hassle for £5 extra a peice saves me crawling under the rear of the car for fun.

The "end" button on the spheres is the filler cap. This is replaced by a valve when re-gassed.
This means the sphere is completely deflated when the cap is removed for fitting of the valve.
Once the cap is removed the serious re-filler companies do an internal inspection of the sphere to check the memebrane is in good nick. Then the valve is fitted and the gas filled to spec.

This means that first time you have the spheres re-gassed - you are charged for the filler valles - which are approx £10 ea.

There are independent re-gassers around with homemade filler equipment. They use a special made filler cup to fit over the end of the sphere when regassing - having the original filler cap just nipped on ready to wind up once filling pressure is reached. Its a special tool clamping and winding the filler cap inside the filler cup such no pressure is lost while cap is torqued.
This method is however not suitable for re-gassing fitted spheres. The spheres have to come off the car.

Dont know of any other brand than the italian made Valprex filler valves - and their suitable filler equipment. The valves are very reliable. Its always a defective membrane that makes a re-gassed sphere go flat again shortly afterwards.