Well, Larry, I made the mistake of actually doing some research of ANSI, ASTM,
and those kinds of documents on the web. And of course, the more you know,
the more you realize you don't know. If I had a PhD in Chemistry, I could
probably make this short, but since I don't have time to get one, this is
long. And no research on this issue of whether distilled water is 'hungry"
for metals.
>From my limited research, it appears that the main problem is, distilled water
does not mean one thing, and it appears that is the big part of the problem
with the different theories and discussions. "Distilled" water can be more
corrosive than ditch water because it usually isn't really "pure" water from
what I can tell. Distilled can mean softened, de-ionized, steam-distilled,
reverse-osmosis, and lots of other processes to "purify" water depending on
the context. An army.mil document talked about how corrosive distilled water
is, but as it turned out, what they were really talking about was the
corrosive nature of the dissolved gases in the distilled water as a byproduct
of the de-salinization systems .For instance.
But it also appears that *with a corrosion inhibitor* any of these "purified"
waters calling themselves "distilled" are going to be much better than most
tap waters, and that seems to sync up with the MB discussion. If you use tap
water of unknown properties, corrosion is secondary to all the other stuff
that can be in there, and that is what causes your Gano filter to get all
crudded up, apparently.
I did the search of the E-Type archives, and didn't find the dissertation by
PhD Chemists I seemed to recall, but was able to find some of the
discussions.
There is also discussion by a PhD Chemical Engineer on team.net that mentions
the issue, and discusses corrosion in general:
http://www.team.net/sol/tech/coolant.html and he recommends "distilled"
water.
But here is what did turn up in my search on the E-Type list. This is
actually a more recent thread where it came up again and somebody asked
Prestone to comment. One would think that it would be to Prestone's advantage
to say you could use just any old water with their product:
Just got this response from Prestone:
<quote>
Thanks very much for your inquiry. We consider the use of a distilled or
deionized/demineralized water to be a better
choice then most tap waters. Tap water will commonly contain harmful
cations like calcium and magnesium that lead to
scale build-up.
<endquote>
I'm close to the end of my list of anti-freeze manufacturers, I've yet to
find one who DOESN'T explicitly recommend purified water over tap water.
And another response from Prestone when it came up a year earlier:
<Dear Eric: Thanks very much for your inquiry. Prestone has not made the
recommendation that only tap water should be used in a vehicles cooling
system. In fact, we did at one point supply a purified water for the cooling
system. The purified water was both demineralized and deionized. The water
was deionized to remove calcium, magnesium and iron (harmful cations) that
otherwise could lead to deposit and scale buildup. The water was also
demineralized to remove aggressive anions, such as chloride and sulfate
which otherwise could reduce the effectiveness of the rust and corrosion
inhibitors found in most antifreezes.
We hope this has been helpful.
Prestone>
So Prestone seems to say that excessive crud would not have occur with
distilled water.
And a quote about water as a solvent:
Well water is a good solvent but is only good at dissolving molecules that
are
> hydrophilic , i.e. water loving molecules, there are many including most
organic
> molecules that are hydrophobic and water is a lousy solvent. This is one of
the
> major hurdles in drug development but then that is another story. Probably
the
> best solvent of all is dimethylsulfoxide.
A two year old thread about de-ionizing water which is "hungry" for metals.
deionise means to remove all the ions from it, these are metal salts usually
those of sodium, potassium, magnesium , calcium, chloride, nitrate, fluoride
etc.
you remove them by either distillation or a process called reverse osmosis.
Cheers, Robin
Ken Thompson wrote:
> on 6/12/01 10:23 PM, rdgc at rdgc@iquest.net wrote:
>
> > Excuse me, why and where did you get the information.
> > Frankly I think that is a load of codswallop, the ions you suggest that
the
> > deionised water is trying to get are not natural to water,pure water is a
> > non conductor and is not ionized if you want to get technical.
> > Cheers, Robin
> >
> > George Badger wrote:
> >
> >> Scott,
> >>
> >> You are correct, de-ionized water is very aggressive about replacing its
> >> ions, regards of the source. SS in some alloys is somewhat impervious to
> >> its attack.
On the other hand, it was pointed out that not all de-ionized water is the
same.
http://newton.dep.anl.gov/askasci/chem00/chem00223.htm
>
> Last entry indicates two types of "deionized" water, that purified
> using reverse osmosis, and that softened using an ion exchange
> column, which swaps sodium ions for water-hardening ions like calcium and
> magnesium. That water will still be full of ionic salts, just sodium salts
> instead of something else. Also indicates that deionized water may still
> contain
> non-ionic substances, like many organics.
>
> So I think one has to be careful to define what kind of deionized
> water you intend to put in the system...
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