Jack Stein wrote:
Drew Lawson wrote:
Jack Stein writes:
So, I'm NOT alone....although you got me by maybe 5 years. I had
thought the tanks were lined in glass, someone told me that once...
Now, I'm thinking metal rusts slower under water than just being
damp? If damp metal is in contact with air, it rusts quickly. Not
much air in water, so, leaving it in might be better than draining it
every day?

Um, no. There isn't much air in water, but there is a hell of a
lot of oxygen.

Good point.

Water contributes to rust so well because water is
self-ionizing (something to do with the shape of the molecule). A
small fraction of the water is always free oxygen and free hydrogen.

Thanks for the link, but I got to tell you, it was way over my head.:-)
I couldn't figure out if it addressed say a nail submerged in water vs a
nail kept constantly wet/damp but not submerged. I'm thinking that a
compressor is always wet on the bottom whether or not you drain it. What
do you think? I don't have a clue myself, but I know I rarely have
drained mine in over 30 years, and it still has no leaks, and the last
time I drained it, about 6 months ago after a similar discussion here
(where I learned the tank doesn't have a glass liner) I drained several
pints of water into a glass container, no sign of rust, and no sign of oil.

I'm also thinking when/if it rusts through, it will go pfsssssh instead
of boooom.:-)

Beyond that, I'm completely ignorant about the details of the steel
that is used for these tanks. Maybe the typical tank-steel rusts
very slowly.

Maybe they use, or used to use, or some use, a rust resistant, high
nickel or something type of metal. I know mine is over 30 years old,
bought it used, and my brothers he bought used when I was 12 years old,
really old then (50 years ago), and it still holds air fine, no signs of
leakage (he drains his though) I remember painting cars with it and it
sounded like it was going to knock itself apart. My brother said if
breaks, he'll buy a nice 2-3 stage compressor... still running still a
knocking. I painted lots of cars and trucks with that thing, and it
proves if you want something to break, it never will.

http://en.wikipedia.org/wiki/Self-ionization_of_water

I used to have a small home air compressor. Over time the air tank
developed a couple of holes. These were in the bottom and would vent air
and water when in use. The pump eventually gave out so I replaced it
with one from HF.