by John
(Denver)
My wife brought home my son in-law’s air compressor for me to use to work on their car and it got air left in it for a long time with out being drained. It has gotten rust inside. is there any way I can clean it or do I need to replace the tank?
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John, you don’t say how big an air compressor, so I wonder if the effort is worth it, if it’s a fairly low cost DIY home compressor?
I suppose, if you were really handy and could disassemble the unit, you might try a light sandblasting, but then that would strip off whatever protective coating that might be left inside the tank.
You could oil the inside of the tank once disassembled, that might help retard ongoing rusting.
Again, depending on the cost of the unit, I wonder if the effort is worth it?
From now on, of course, make sure you leave the drain valve open when your compressor is stored.
Anyone else have any thoughts for John?

Using tool oil for the tank
by: Anonymous
Air tool oil could coat the tank. it’s good for the tools, too. though, if you’re ever going to use the compressor for spray painting… I don’t know if it’s a good idea.
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Interesting thought. I’m against injecting oil into the tank. Even though the air tool oil is good for lubing tools, by the time that oil gets into the air stream, along with all the other crud that’s in the tank bottom, that wouldn’t be good for tools, nope, for sure not.
Cleaning tank
by: PCBEACHRAT
DO NOT ADD ANY type of rust preventative, or coating of any sort!!!If you add oil into that tank or any type rust preventative, you will NEVER get it all out,and say goodbye to ever wanting to spray paint,sandblast,or any other air function that needs to be clean..the sulpheric acids and other chemicals in rust convertors will ruin air tools one after another..No matter how many filters etc you use..you have just ruint this tank for future applications..I build pumps, sandblast and paint from a shop from my home..The reason the factory doesn’t coat the inside of the pumps is becuase of heat transfer..an uncoated inside of the tank will absorb alot of the heat,which in turn produces alot less moisture in the tank…if you coat that tank the pump will get 4 times hotter than designed,harsh residual chemicals in it will ruin every air tool yiou use thereafter..TANKS ARE NOT MEANT TO BE COATED..THE BEST YOU CAN DO IS DRAIN THE TANK after every use, AND WORK THE RUST OUT OVER TIME..NO QUICK FIXES HERE WITHOUT RUINING THE PUMP OR TOOLS
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Just a guess
by: Chuck
Just a guess here as I have never tried it on a compressor tank, but I use Evapo-Rust to remove rust from my tools. It works quit well, and it is reusable. You would need to fill the tank and leave it over night then rinse it out and dry it. Evapo-Rust only attacks rust, so it is safe to use. I keep a bucket in the garage that I drop rusty tools into. But it might cost more than the tank is worth.
Another option might be to drop some large ball bearings or nuts and bolts into the tank and shake it. That would break up any flake rust. Again, I have never tried it.
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Thank you for the suggestions, Chuck.
PCbeachrat… I work for a major brand air compressor company who shall go unnamed… We offer coated and uncoated tanks. The heat transfer claims he makes are utter hogwash. He is literally Making. Things. Up.
I just wanted to clarify that many manufacturers do coat the inside of their tanks some charge over $200 to do so. That would seem to perhaps void the input of the above poster that untreated metal handles the heat better, not sure why someone would think that?