Spheres, Pressure measurement results

[kenhall1202]

Hello readers

Here's a little food for thought and comment now that the nights are drawing in!

I finally got round to making myself a sphere pressure tester (based on the design by Noz in the self help files) using a BX rear suspension cylinder, an old Dunlop bottle jack, various bits of angle iron, threaded rod and of course a 1000psig pressure gauge. I'll post a picture if anyone is interested.

Having done two lots of sphere changes since I acquired my (1996) 2.1TD in 2001 I thought it would be interesting to check the residual pressures in the old spheres which I had kept hold of with a view to possibly recharging them.

The results are presented in the attached Word file.

I realise that this is only a very limited sample but there are some interesting initial conclusions to be drawn.

1. Note how well the original Citroen front suspension spheres with 'Multicouche' diaphragms have retained their pressures (only 6 to 7% pressure lost in 11 years!!), compared to the other Citroen originals which use the polyurethane 'Desmopan' and 'Urepan' diaphragms.

This begs the question why didn't Citroen use the 'Multicouche' diaphragms exclusively in view of the better pressure retention and longer life? I'm aware that Citroen did use the different diaphragm materials on export XM spheres according to the local temperature conditions so it may be related to this. The cynic in me says that maybe they just wished to keep on selling replacement spheres.

The longer life of the 'Multicouche' spheres would explain why the French guy (see original post in French and translation elsewhere on this site) went to all the trouble of removing the damper from such a sphere so that he could use it as an accumulator.

2. Unused Citroen and Amtex new spheres (assuming they have been fully charged in the first place) do appear to have a long 'shelf life' and (for the reasons that Noz has eloquently presented in earlier posts) lose pressure only very slowly.

3. On the basis of just mileage it appears that Amtex spheres (in use) do lose pressure more quickly than the Citroen ones. This suggests that recharged genuine Citroen spheres from Pleiades might be a better bet than new Amtex of unknown pedigree. By the way has anyone tried the Spanish 'Lizarte' spheres which have recently appeared on eBay? I looked up their website and they appear to be a well established manufacturer of spheres and remanufactured hydraulic items.

Regards

Ken

2/10/07 PS Has anyone had trouble opening the attachment? It came back with symbols and text all mixed up when I tried it this morning. I will re attach it tonight.

This post has been edited by kenhall1202 on October 02, 2007 08:23 am

[mackay1]

Hi Ken,

A really interesting post - thanks. Once I've had a chance to digest it I'll come back to you with any questions.

I'd be interested to see a photo of your rig too if you have time to post it.

Many thanks

Roy

[DerekW]

Yes please, Ken.

Derek

[carlos774]

Hi Ken , I'm only getting symbols and text as you say.
Cheers, Carl

[rowanmoor]

To view the file you will need to right click the link and select 'save target as...' (assuming IE, not sure what the equivalent options are in Firefox etc, but should be easy to find). You will then need to save it to your PC - changing the extension to .doc and then open it from there.

This forum always seems to have this problem with attachments. Something to do with MIME types I should think.

Very interesting document though.

This post has been edited by rowanmoor on October 02, 2007 10:02 am

[kenhall1202]

Thanks Rowanmoor for that tip - it does the trick.

Ken

[carlos774]

Works for me......... .Thankyou.
Carl

[kenhall1202]

Hi Roy and Derek,

Apologies for the delay, here (attached) are the pictures of my sphere pressure tester. The critical part was the top plate which takes the thrust of the cylinder. I used a piece of scrap 1/2 inch thick alloy plate and cut a central hole with a 50mm hole saw. I then turned out the hole sufficiently to match the external cylinder diameter at the shoulder. It was also necessary to mill out a slot to allow the BX cylinder pipe boss to pass through.

The pictures show an unused Citroen accumulator sphere with a charge pressure of 60 bars.

Regards

Ken



This post has been edited by kenhall1202 on October 09, 2007 09:01 pm

[kenhall1202]

Here's the 2nd picture!!

Ken