Date: Wed, 17 Nov 1999 14:27:22 -0800
Reply-To: Alistair Bell <albell@UVIC.CA>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Alistair Bell <albell@UVIC.CA>
Subject: Re: DM: Re: VW coolant
In-Reply-To: <3.0.5.32.19991117075300.0081f420@rockisland.com>
Content-type: text/plain; charset="US-ASCII"
on 17/11/99 7:53 AM, T.P. Stephens at doktortim@ROCKISLAND.COM wrote:
>
> When the
> buffers in the coolant go south, they go exponentially. You can test pH to
> confirm the buffers are gone. If you get a 6.5 pH, it is proof that you
> don't yet have a 4 gallon battery going on. But it can be 7.5 in another
> month or 1000 miles. Once ion transfer begins, the march of aluminum atoms
> to take vacations and "See the System" begins. Gee, if we had some
> phosphate we could really get the tranportation system going. The steel has
> free ions for the asking. The aluminum, now out free and roaming thanks to
> the acid, is asking. A mutual agreement is founded to create a micro
> amperage battery of the cooling system. The acids eat the aluminum, and the
> steel at a much lower rate, and provides the atoms to build the crystals of
> scale that act like ice at the seams, fittings and flanges, wedging their
> way to freedom from the system.
>
> If there are phosphates available to enhance ionic transfer when the
> coolant shifts to acid, you have a handy transfer infrastructure already in
> place. The Neaderthals knew this from the data they obtained when first
> studing the realities of their proposed mixed metals products. This is a
> long standing specification for all the DM school.
> Porsche/VW/Audi/MB/Opal/Volvo/Saab/Peugeot and others. Even the English
> apes have followed suit as Jaguar specifies the same for their mixed metal
> mechanisms.
>
>
What the heck are you talking about? You talk about the coolant pH going
from 6.5 (slightly acidic) to 7.5 (slightly basic) and then go on to talk
about the coolant shifting to acid.
Buffers are necessary in the system, and by nature are ionic. A buffer
system is an ionic solution!
Phosphate buffers (and the borates ands silicates in "traditional" coolant)
will precipitate out, especially in hard water, and will coat heat exchange
surfaces lower the heat transfer efficiency.
The long life coolants use carboxylate buffers rather than phosphates
Even Neanderthals know that the pH is a measurement (neg. log) of the
hydrogen ion (proton) concentration (actually in water it would be
protonated water - H(subscript3 )0(superscript plus). It is a logarithmic
scale, pH 6 having 10 times more H(superscript plus) than pH 7, pH 5 - 100
times, and so on.
Coolant becomes more basic - pH going UP - as it ages. Basic (alkaline)
solutions are the death for aluminum - will cause corrosion far quicker than
acidic solutions.
That said, measuring the pH of your coolant is a good way of determining the
quality/age of the stuff. I would test it every so often and observe the
change/trend.
There is a company that makes test strips to measure the pH and also the
glycol concentration (which according to the company is based on the same
enzymatic assay as used in glucose test strips used by diabetics to measure
glucose concentration in urine and by me to measure glucose concentration in
bacterial fermentations).
The web address is :
http://acustrip.com/prd3001.htm
For a good summary of co0ling system theory and practice have a look here:
http://www.dp.doe.gov/CTG/bpwg/cooling.htm
Alistair (I use 18 mega Ohm water plus prestone longlife orange coolant)
