"mike regish" wrote in message
. ..
Well, the water bath does keep the skin cooler, but that is because the
water increases the tanks ability to shed the heat produced in the gas.
The
heat goes from the gas to the tank to the water. Over filling the tank and
letting it cool could over stress the tank. Not a good idea, IMO. Like you
say, much better to fill it slowly enough for the heat to dissipate to the
surroundings, be it air or water, and you get a full tank. Those tanks are
already under tremendous stresses without not only going over pressure,
but
doing it when the tank is hot and the tanks strength could be weakened
with
enough heat.

More of a concern for the aluminum tanks than the steel ones... I've had
fills that were hot enough to the touch that I wouldn't keep my hands on
them... Probably not as hot as a black car left out in the sun during a
Houston summer though... grin

When they overfill them, they'll prehaps put 3300-3500 psi into a 3000 psi
tank... Considering what the hydro test pressure is for the tank, that's not
that big of a deal... One concern with a fast fill on aluminum tanks is that
since the tank is about 1/2 inch thick, there's a difference between the
surface temperature of the tank and the inner wall temperature which could
result in a greater chance of cracking... It is believed that having the
entire wall thickness the same temperature is less likely to produce a
problem... Well, at least that is what I've read on the issues over the
years... There's still come companies that fill with water baths and even
some who refrigerate the water in the bath, which probably further compounds
any potential problem that there might be... Personally, I prefer not having
my tanks filled in a water bath... If nothing else, it means that any
contaminates on the tank are at least my own doing, not what might have been
in the water bath tank...