re:
" The advice I've received from individuals as well as from the radiator
specialists is to never use distilled water in a radiator. Just use regular
water. My very unscientific understanding is that distilled water tries very
had
to become hard water, pulling extra molecules off the cooling system and
actually causing corrosion. "
Yes, that is very unscientific, in the realm of urban legend. Probably comes
from somebody's high school chemistry class where they discovered that
distilled water will dissolve more table salt than the local tap water (no
wonder our schoolkids don't do well in science). This is due to the fact that
tap (typically "hard") water is already partially saturated whereas distilled
is not, and therefore will dissolve more salts. Very bad indeed for engines
made out of table salt; however, most of our engines are made out of elemental
iron which, while prone to corrode and produce soluble iron oxide when bathed
in a hot electrolyte--i.e. water with dissolved salts in it--does not
otherwise surrender its atoms that willingly, no matter how hard the nasty
distilled water tries to steal them. In fact, I believe (not sure) that the
corrosion inhibitors in antifreeze are slightly acidic--oxylates, like a
compound found in rhubarb--to neutralize (or 'buffer' ) the increase in pH
produced as the metals do corrode and dissolve.
The fact is, distilled water is chemically neutral, with pH of 7.0 due to a
balance of hydronium (H+) and hydroxide(OH-) ions. It is much less capable of
promoting corrosion than either an acidic--pH less than 7--or
basic/alkaline--pH greater than 7--liquid (think battery acid and dissolved
Drano, respectively). That is why noted mechanics--Click&Clack, Dr. Gizmo and
others--recommend distilled water. Also, the premixed solutions are blended
with distilled or deionized water (ex. http://peakantifreeze.com/peakrtu.html
http://www.peakantifreeze.com/faq.html#B).
Actually, deionized seems to be the new favorite, as it contains even fewer
stray ions than distilled, as distilling does not remove all ions (but it does
get the good stuff out of the corn mash).
bs
--------------------------------
Bob Spidell - San Jose, CA
The advice I've received from individuals as well as from the radiator
specialists is to never use distilled water in a radiator. Just use regular
water. My very unscientific understanding is that distilled water tries very
had
to become hard water, pulling extra molecules off the cooling system and
actually causing corrosion.
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