[urq] Fw: RE : The "Bomb" possible cure and a question

[Louis_Alain_Richard@computerhorizons.com]

"Patrick Carlier" <p.carlier at pandora.be> wrote on 2005-08-25 12:51:34:

> Hey I didn't even knew Citroen sold cars across the ocean .
> Anyway , you're right . These are citroën spheres .
> A new one round here costs about 90$ .
> A good and refilled one costs 30 $ .
> Ur-q reservoir is close to 200$
>
> There are five of these in each citroën .
> Only the one at the pump can be used . So you'll need the
> accumulator one , not the four suspension ones  .
> The std pressure is 63 Bar . And they used red atf just like the ur-q 's
.
> Round here citroen dealers have the right equippement
> to recharge them . At any wanted pressure below 100 bar .
>
> It all started out when a friend of mine had a hydraulic failure
> on his Coupe 20V . These "bombs" are outrageously expensive .
> About 800USD . And dealer only , and not rechargeable
> Then I said , lets repair it .
> Someone else said it's iimpossible . Wich led to a discussion
> No ,yes , NO , YES dammit , and before I knew it , I had accepted
> the challenge , and then thought it would work for fine for the ur-q also
.
> The 20V bombs are  a little harder to fix cause the spheres are
> welded to valve block . But it can be done , thats for sure .
>
> Pat
>
>
> ----- Original Message -----
> From: <Louis_Alain_Richard at computerhorizons.com>
> To: "Patrick Carlier" <p.carlier at pandora.be>
> Cc: <urq at audifans.com>
> Sent: Thursday, August 25, 2005 5:45 PM
> Subject: Re: [urq] RE : The "Bomb" possible cure and a question
>
>
>
>
>
>
>
> OK now, I see where you are going with that.
>
> Aren't these accumulators the "green spheres" from the DS-SM Citroens ?
How
> much are they sold in Europe ? I am pretty sure I can find some here in
> Canada, there is a huge Citroen garage (with as much of 50 cars in a
field)
> no far from me.
>
> Beware though, as Citroen used different hydraulic fluids depending on
the
> model year. The Bombs-spheres for our early urQ cars must used the
standard
> ATF red fluid, so the sphere's membrane must withstand this type of
fluid.
> But then, ATF is a "thick" fluid, compared to the "thin" Pentosin CHF-7.1
> and CHF-11s, so it might not be a problem with the Citroen spheres.
>
> What type of fluid the Citroen are using ? And what is the operating
> pressure of the Citroen hydraulic system ?
>
> Louis-Alain
>
>
> "Patrick Carlier" <p.carlier at pandora.be> wrote on 2005-08-25 11:22:15:
>
> > You are right offcourse .
> > I forgot the Kelvins , and calculated in
> > Celsius .
> > My university days are also a long time ago .
> >
> >
> > Thx for thinking along .
> >
> > Pat
> >
> > ----- Original Message -----
> > From: <Louis_Alain_Richard at computerhorizons.com>
> > To: "Patrick Carlier" <p.carlier at pandora.be>
> > Cc: <urq at audifans.com>
> > Sent: Thursday, August 25, 2005 5:10 PM
> > Subject: Re: [urq] RE : The "Bomb" possible cure and a question
> >
> >
> > Maybe my chemistry is too old, but my calculations shows an ambient
> > pressure of 29 Bar.
> >
> > To achieve that number, I used the PV=nRT formulae, the Perfect Gases
> Law.
> > Don't forget that the temperatures in this formulae are to be expressed
> in
> > Kelvin, not Celcius or Fahrenheit.
> >
> > The figures are :
> > Gas volume is constant, if the accumulator is empty of oil.
> > P1 is 32 Bars at T1=313 Kelvin (273K + 40C)
> > P2 is unknown at T2=293 Kelvin (ambient 20C + 273K)
> >
> > From that, considering N2 as a perfect gas, we find
> > P1/T1=P2/T2
> > then
> > P2=P1*T1/T2
> > P2=32*313/293= 29 Bar
> >
> > Am I right ?
> >
> > Louis-Alain
> >
> >
> >
> > urq-bounces at audifans.com wrote on 2005-08-24 15:45:22:
> >
> > > Datasheet says :
> > > Maximum accumulator efficiancy is achieved when the
> > > Pre charge pressure at operating temperature equals
> > > 0.9* the minimum system pressure .
> > > Maximum operating pressure should not exceed 4 times
> > > the precharge pressure .
> > >
> > > So that would be 0.9*36 = 32 Bar at operating temperature .
> > > Givven this , ambient precharge pressure can be calculated .
> > > What would normal operating temperature be ?
> > > My best guess is 40°C/100° F .
> > > In that case , ambient preset pressure would be 22 Bar .
> > > As for the max pressure of 57 bar , or even 75 bar in a worst case
> > situation
> > > that is still below 4 times the preset value .
> > >
> > > Please , any thoughts / comments are welcome
> > >
> > >
> > > Pat
>
>