On 5/5/2013 9:56 PM, HeyBub wrote:
woodchucker wrote:
Hey,
I bought a compressor from a garage sale yesterday.
Paid $20, seems to be between 13 and 20 gallons.
What I wanted was an oil type compressor that uses a belt.

I could not take the oil less type of noise anymore.

I thought I was taking a risk, pretty rusted on the outside, but
didn't appear deeply rusted. I shook the thing did not hear water in
it (WRONG)...

When I got it home still did not hear water in it...
opened up the petcock after charging it up and holy crap the most
rusted water... and probably a pint to quart of water came out.


So what chance do I have of saving this tank? Where I used to live we
had a scales air compressor place nearby but they closed... I don't
find any of them around any more.. not close by.
The rust on the outside is all superficial and can be sanded and
painted ... I need to get into the tank with a 3/4 square end and
see.. Anyone have some real info on how to treat this?

Thanks.

From Wikipedia:

--- begin quote
Phosphoric acid may be used as a "rust converter", by direct application to
rusted iron, steel tools, or surfaces. The phosphoric acid converts
reddish-brown iron(III) oxide, Fe2O3 (rust) to black ferric phosphate,
FePO4.

"Rust converter" is sometimes a greenish liquid suitable for dipping (in the
same sort of acid bath as is used for pickling metal), but it is more often
formulated as a gel, commonly called "naval jelly". It is sometimes sold
under other names, such as "rust remover" or "rust killer". As a thick gel,
it may be applied to sloping, vertical, or even overhead surfaces.

After treatment, the black ferric-phosphate coating can be scrubbed off,
leaving a fresh metal surface. Multiple applications of phosphoric acid may
be required to remove all rust. The black phosphate coating can also be left
in place, where it will provide moderate further corrosion resistance (such
protection is also provided by the superficially similar Parkerizing and
blued electrochemical conversion coating processes).

--- end quote

This is how "black pipe" (used for natural gas distribution) is created.



And, from one blogger:

"Look for it as Metal Prep oluton. It's available at any lumber yard, borg,
or hardware store in quarts and gallons in plastic bottles. I use Jasco out
of blind brand loyalty but it' a good consistant product. It has tuff in it
that makes it work better than the plain acid. I dilute it 10 to 1 in a 5
gallon pail. When the blue color fades the acid has pooped out so add more.

"It's sewer safe when exhausted. Or since the spent solution is mostly iron
phosphate it makes good fertilizer. Run it through a proportioning squirt
nozzle and water your flowers."


So if I can't scrub it off, will it still work?

--
Jeff