Est. 1998 — 27 years of woodworking knowledge
new air tank
Buck Nall
Bottom end has large screw out plug. Poured in Qt. rust=oleam. 516 dowel, split end tripled layered thick cloth couple inches wide bout 6'' long, slid'm down in that split dowel, wired end tight, with Oluem puddled at/in bottom, made sure cloth got saturated, lectric drill on other end of dowel. turned it tll I wuz satisfied entire surface of INSIDE WAS COVERED. no never tried to drain luem left it to do it magic in bottom.
Thank you, Jabba the Hutt
Huh?
Reading between the lines
Ellis Walentine
Buck, you didn't mention what kind of air tank you're talking about, but I get your tip about using a split dowel and a cloth to distribute your rust inhibitor or whatever. Thanks.
Ellis Walentine, Host
Re: Reading between the lines
buck nall
Thanks my friend, oh shoot, I probaply ought not say THAT HERE!!!! What kinda air tank, everyone was/has been talking bout THEIR SHOP AIR TANK!! Figured any and everybody would assume I was talking bout the same. Sir, really SIR, with the two responses to my original explanation, I really believe I should leave these CHILDREN ALL BY THEMSELVES!! i'll lurk and leave these youngsters to their fun.
Re: Reading between the lines
William Duffield
No, you ought not say THAT HERE; It's either "that there" or "this here" 
painting inside a compressed air tank
John K Jordan
Without the inside surface being properly prepared by careful cleaning at minimum, or better, with abrasives and primed, my concern would be paint may not adhere in the long term. Might inspect the inside after some use with a borescope. If paint peels loose a screen on the output from the tank might prevent dry paint peelings from getting into the air lines and clogging tools and such.
One way to clean the inside of a tank is by tumbling with abrasive grit.
I wonder if air compressor tanks are typically painted inside when new. If so, how is the inside prepared?
Judging from the rust color of the water that drains from my air compressors I suspect the insides are not painted. I don't remember steel tanks I've inspected appearing to be painted inside. If not, why not? Perhaps there is a good reason besides the extra cost.
JKJ, former pressure vessel inspector and tester
Bet it's cost...
John in NM
No one does it due to cost, and compressors are more or less disposable unless you're up in the true industrial price range. Like I said, only brand I've ever seen that didn't produce rusty water was Speedaire (and that was 20 years ago).
painting a very bad idea
Bill Tindall, E.Tn.
There is a specific kind of corrosion that establishes when there is a breach in a paint film in the presence of high humidity. It aggressively bores holes in the metal at the paint-breech interface.
For the curious.......where the metal is exposed in the breech the metal will be cathodic and reduce oxygen. The electrons to do the oxidation will come from an oxygen deficient area under the edge of the paint breach resulting in Fe= Fe++ + 2e, an oxidation of the iron to make rust.
Get a scratch on your car and watch it happen (well maybe not with a modern galvanized steel car steel before painting.) Many will have observed a paint "blister" under these conditions.
Re: painting a very bad idea
Barry Irby
This matches up with what the plumber who worked for me when I was a builder said.
He thought glass lined tanks were a bad idea. His idea was that if there were a scratch or pin hole in the lining all of the corrosives inside the tank would attack the one spot and corrode through. But in an unlined tank the corrosives would be spread out over the entire surface and thus less intense. I don't know if he was right.
Wonder if an anode attached to the outside of the tank would help? How about on the inside? Could you just drop a piece into the tank? Is there a way to install one like the ones on water heaters?
Makes me wonder...
John in NM
Those compressors I saw that didn't supply rusty water out the bottom - perhaps they were galvanized rather than painted inside. Never thought of that.
Re: Makes me wonder...
Pete in Holland MI
Have tried painting a small 2 gallon air tank one time. 1/4" NPT ports (3) in it. Took weeks to dry, as there is very little air circulation in there and not much to aid evaporation.
Drain your tanks regularly.
Re: "...leave these youngsters to their fun."
Yonak
Buck, here's my take and why I'm embarrassed by the way you express yourself :
As a fellow Georgian, it would surely pain me if anyone would mistakenly think people of our state really talk the way you do. I got a pretty good education in Georgia, I believe and, you may speak any twisted way you want to but, I sincerely hope no one would think any Georgian would talk in the ignorant, contrived, back woods dialect (that never was) that you represent.
Rant off .. I apologize to everyone else for this reaction before this group.
As an educated redneck...
John in NM
I'll stick up for the guy. No one else is, although Ellis is a class act, as always.
People do talk this way. Maybe not in Georgia, but I know more than a few who speak the western version of backwoods. When I lived in Maine I knew more than a few who's accents and lingo would have puzzled Bert and I. But then I often find myself living in the backwoods.
I only know one person who writes email in vernacular - just as she speaks.
I know more than a few who now speak as they've learned to text -- actually saying dumb stuff like "my car needs washed" instead of "my car needs to be washed".
So cut the guy a bit of slack. Perhaps polite tolerance will bring the tone of the place up a bit.
Like I said, Ellis is a class act and always has been since I started coming here in 2002. If nothing else, I feel that I owe him polite, reasonable posts when I can manage them, and I feel regret when I get hot headed.
Re: Reading between the lines
Buck Nall
Ellis or MR.Ellis, now that I've been bruised and told how ignorant I AM, got a ???.
Wonder how many of these educated children have a pull cord on the (air tank)bottom drain valve that 18 wheelers have so a quick pull of/on that cord, and let go to BLOW ALL the accumulated rust, PAINT, corn cobs, dead rats, crows AND OTHER ACCUMULATED crap outside the shop.
OK.
I realize THIS IS PRETTY complicated, but, MAYBE some of the more educated will explain.
Pull My . . .
Mark Mandell - Gone Round In New Jersey
well, actually, Buck, I did away with just such a rig on my compressor in favor of an air-activated drain that vents all that s . . (stuff) outside one time in each cycle when the pressure drops by 15 psi. I just have to clean & lube it once a year.
Not a question of education, just acquired knowledge from people who know more than me.
PS
Mark Mandell - Gone Round In New Jersey
If Buck, you hang around here to learn stuff, you'll get more faster if you write your question such that people don't need a translater to understand what you've asked.
PPS
Clifton C
It's more fun to read the responses then the question.
Re: PPS
Buck Nall
Aint it the truth!!!!!!!!!!!!!
Re: painting a very bad idea (galvanized)
John K Jordan
>>>Get a scratch on your car and watch it happen (well maybe not with a modern galvanized steel car steel before painting.) Many will have observed a paint "blister" under these conditions.
Bill, you seem like a person who might be interested in this. The process used in at least some situations is galvannealed steel instead of galvanized. The zinc coated steel is heated and annealed forming a zinc-iron alloy which has superior protection properties. There is a lot on the web but this page has a clear comparison and describes some detail about the corrosion resistance.
And this: https://en.wikipedia.org/wiki/Galvannealed
I don't remember the year ('80s, '90s?) but when I worked at the Lab we had a project working with a major automotive steel producer to help quantify parameters of the galvannealing process. For sheet steel the galvanneal process moved the sheet upwards through a large vat of molten zinc. High above the vat were induction heaters which raised the temperature to form the alloy. It can be difficult to precisely measure the temperature of precise points on a rapidly moving sheet of steel with a shiny reflective coating. Researchers in our department had developed a method to measure temperatures by phosphorescent decay. A nozzle sprayed a phosphorescent powder onto the surface of moving web in several places after leaving the zinc bath. Zapping the powder created a pulse of phosphorescence. Optical equipment measured the light output. It turns out that the decay time of certain materials is related to the temperature allowing precise non-contact measurements. Knowing the precise temperature at various points on the line let the engineers improve their understanding and make improvements with less guessing. At that time I did technical 3D modeling and animation and my task was to model the process and produce video and graphic materials to let the researchers explain and document the entire process, perhaps for publication and patent purposes. Seeing the process in action was fascinating.
There is another process called galvalume which coats ferrous metals with zinc, aluminum and silicon, common in the metal roofing industry. I have no idea if it's is used for automotive applications (or for air compressor tanks!) I used galvalume 5V roofing on my shop and barn.
JKJ
Paint Will Fail
Mark Mandell - Gone Round In New Jersey
Quickly because the tank is constantly expanding and contracting with the temperature and pressure changes so the paint film will likely fracture starting at the weld seam.
Water heater tanks can be glass lined because the changes (30psi range) will be minimal and can be addressed with the type of glass used.
My IR compressor's discharge has been rust-free for most of its 20-year life because of the auto drain and extra piping I installed. Discharge is mostly clear with a tiny bit of oil. It's rare, indeed, that I get any condensation out of the drip-legs incorporated into my pipe system.
Re: Paint Will Fail
Yonak
Mark, can you explain your system ?
System *LINK*
Mark Mandell - Gone Round In New Jersey
OK.
The compressor is a SS3L3 Ingersol with a 60 gal receiver. Oil lubed, 220v.
The stock drain (POS) was removed and an adapter put in. Piping from that out beyond the tank's side is 1" brass. Pipe then reduces to 1/4" brass to which the auto drain is attached. The drain is a Wilkerson #50 air activated unit that purges once following a pressure drop of 15psi following a repressure run by the compressor. You can see the drain at McMasterCarr at Part No.4919K13 (link). The extra large piping acts as a reservoir for condensate between purges in order to keep fluid out of the tank. The drain is connected to tubing that vents outside.
Once a year I take down the drain, clean and lube it with synthetic grease and reinstall. I have used a rebuild kit once in the 15+ years I've had the drain installed.
My supply system is soldered 1/2" type L copper. Each of the 4 air "stations" (with or without regulator) has a drip leg that vents into a plastic (recycled) water bottle through a 1/4" ball valve and tubing.
Must admit, I've gotten a bit lazy checking the drip legs because it's rare that I get anything from those vents.
Hope this helps
Valve
Thanks
Yonak
Thanks so much, Mark. I have to admit I'm not smart enough to understand all that's going on here. ..But I got a sense of all the work that's involved and my lack of competency and ambition in some areas of the piping. Then I saw the price of the valve and I think I'll get a replacement tank when it rusts through. Thanks for all your explanation.
Re: Cost
Mark Mandell - Gone Round In New Jersey
The price of the Wilkerson has more than doubled in the time I've had it. It's probably not economical to put one on a smaller compressor that only sees occasional use or gets moved around. I also have a small 2hp twin-tank Thomas that I use when working outside of the shop. That one gets drained and left vented when not in use so condensation is not an issue.
Aside from keeping the storage tank and air dry, the auto drain's big benefit is taking "drain the compressor" off the to-do list. 