Soda blasting

[sgtslag]

Thanks...  I think.  

I read somewhere, recently, about checking older air compressors for rusting, and weakened areas of the tank, from rust.  The author was warning that the tank can rust from the inside, weakening the metal, and that it is a good idea to test them, periodically, with a hammer tapping, to ensure the metal has not become dangerously thin -- could cause a bit of an explosion of sorts.  I recently pulled the plug on it, to drain any water out of the tank -- none came out.  I found a region on the underside that appeared to be rusting, but it is solid.

After I acquired the compressor, I decided to change the oil, as I had no idea how old it was (similar experience with the fork oil on the Honda, after I bought it...  same green color).  What came out was interesting:  thin, typewriter-like oil (very thin, very clear; small amount of this), and (the rest was...) hunter-green goo.  I wondered if anyone had ever changed the oil in that thing in the past two decades -- it seemed as though the heavily contaminated oil had separated out, somewhat.

I share this in the hopes that others will take note, and take good care of their compressors.  I loaded mine with Shell Rotella T6 synthetic (spins over much easier, faster, smoother...), but since then, I have done some research on compressor oils.  I learned that compressors will work just fine (based on experience of posters on the Internet; some claimed auto oil worked fine, for 20 years, in compressors they use for shop air tools, every day), with detergent automotive oils.  Others maintain that compressors have no oil filters, so non-detergent oils are better because any sediment/particles will settle to the bottom of the oil pan, rather than being suspended within the detergent oils.  In the end, I don't think it matters all that much.  Compressor oils are just 30W non-detergent oils, and any such will do -- you do not need to buy "compressor oil". YMMV.  Cheers!

[Piute]

We just add another air tank to are older then me compressore(180gal.),the 1st got a hole in very bottom (vertical)and only new because could just bearly hear it,but just turned it off for about  a week ,thought of it blowing, and used porta-potty one,(25 gal.on wheels),there a reason I call them porta-potties cause they are not worth  $h!^ when it come to turning auto-body tools,D.A.(dual action)Flat boards,but shoot a nail cross town 
  When got new tank just ran lines to new rather then cut and re-weld base to new,
  They say that it can dammage the tank If not done by a pro.
looks like a "still" with copper coils on it.
  Yeh water traps are a must,even a potty will get condensation in day use ,some use inline oilers but just couple drops before use is a good habit and drain tank water and traps before painting AND small water filter near gun2k paint job shot cause of couple drops of water
...Piute N Judose...

[TOOLS1]

When I was younger. My Dad had an air compressor in his garage. He kept it under a workbench. The workbench was made out of 2 1/2 inch angle iron, and 1 1/2 inches of plywood. It was 12 feet long X 30 inches wide. It had a big grinder, and really big vise attached to it. It also had a huge storage bin filled with nuts, and bolts.
Any way, one evening I needed to do something in the garage. It was freezing cold, but I went out, and turned the compressor on. As I was getting tools lined up I noticed that the compressor had been running, for quite some time. I thought something might be wrong, so I went over to unplug it (the plug was on the wall above the workbench). I reached over the workbench to unplug it. When all the sudden it blew. The workbench came up into the air at least a foot. The garage was filled with some sort of smoke/steam? After I composed myself. I made my way to the door. When I opened the door I noticed my Dad at the back door to the house. He was looking out with a bewildered look on his face. When he seen me open the garage door. He hollered "what the hell did, you do now?"  not are, you all right, but "what the hell did, you do now?"
When the smoke cleared. We inspected the damage. the compressor tank was wrapped around a now bent angle iron brace on the workbench, and the side of the garage had a 6 inch X 3 foot bulge in it. Broke 2 2X4 studs. The switch, and safety valve had frozen.
Air compressors can be dangerous. However if, you keep the tank drained, and make sure all the safety devices are working there should not be any problems.
TOOLS
P.S. I used to work as a Boilermaker. All the testing was done with water. Not air!!!!

[Piute]

 "what the hell did, you do now?"Yep I think my name was nobody cause when nobody did it I got the blame>>>Piute<<<

[Dw07u]

Tools...

Glad you survived!

[Peterwh]

I'm glad you survived too.  You were very lucky.  Many others have not been so lucky.  You can be killed by the explosion from an over inflated tyre.  That's why professional truck shops inflate gyres in a steel cage.

Maybe not everyone knows this but the reason you pressure test with water, and not air, is that air (any gas) is compressible, and therefore can explode, whereas a liquid, eg water, at least in theory, is not compressible, and cannot explode.  If the vessel being tested does rupture, it just goes with a bit of a phut.  That's why we use brake fluid for our hydraulic brakes, because it is incompressible and transmits the force applied through the lever directly.  It's the rubber hose that expands, not the liquid that compresses to reduce the effectiveness.  Also, that's why we bleed the air out, because the air compresses causing that spongy feel.

Before anyone asks why trucks use air brakes, that's because the air holds the brake off, not on.  You release the air pressure and the brakes are applied by springs.  It's also a fail safe device.  If the air supply leaks or fails, the brakes are applied.

[TOOLS1]

Thanks guys I'm glad I survived to. If it had not been, for that workbench. I would not be here today. Peter. You are right on the money with your explanation of why water/fluid is used. We used to test some vessels to 2,000 psi.
TOOLS

[Piute]

  good explanation there Pete

[Peterwh]

Thanks

[TOOLS1]

I went to Harbor freight today, and got the 15 lb soda blaster (along with a few other things). I can't wait to try it out tomorrow. I have a lot of parts to clean.
TOOLS

[Dw07u]

I bought a air compressor kit yesterday, tried blasting some soda, but didn let it get up to proper pressure, will try later today... anyway, here are some pics...




Tools, how about some pics of that soda blaster you bought?

[TOOLS1]

Here is a link to the one I bought. There is a video of it being used. I hope to have time tomorrow to try it out. http://www.harborfreight.com/15-lb-portable-soda-blaster-66742.html
I hate to be the bearer of bad news, but, you will not get much done with that air compressor. It is way too small, for blasting. You will only be able to do small spots at a time, and spend a lot of time waiting, for it to build pressure again. Sorry.
TOOLS

[Dw07u]

no worries, I only have small spots to do anyway, and I really could not afford the bigger one, and besides, I can use this one for alot of other stuff too

[TOOLS1]

It should be fine, for airing up tires, and running a nail gun. Just do not over work it while soda blasting. Let it cool down once in awhile.
TOOLS

[shinyribs]

I wonder why they dont just build compressor tanks out of aluminum so rust-thru wont be an issue?I guess it would cut down on repeat business,huh? Glad mine sits in another roomcant get to me

[Dw07u]

I won't, and I think that little guy is gonna surprise us, just wait ;)

Yes well repeat business will be cut down when aluminum is used. Production costs will also rise, and if it blows up in your face it is likely to cause more damage, since it's a slightly softer metal(and will most likely fling more pieces of metal at you), and you just would not get that thick blue paint with the big welding spots, tubular handle, "this is a huge chunk of metal" feeling with it...

then again, these guys(not mine specifically, but ACs in general) can last years, just ask SGTSLAG  so rust can't be that bad...

[TOOLS1]

Ridged makes an aluminum air compressor. So do a few other company's. I just can not remember which ones. If, you keep the tank drained it will last, for years.
TOOLS

[shinyribs]

All true.Mine is about 16-17 years old.Its a Speedaire.I know that water and oil dont mix    and that water will sink to the bottom.but when i got it new i dumped a quart of gear oil in thru the tank plug.Im paranoid like that.I doubt it did any good,but i still felt like it would help at the time.oh well

[TOOLS1]

Remind me never to paint with your compressor.
Here are some pictures of my new soda blaster. I did some blasting on an old engine case that sat in water, for years. It took most of the crap off, but the case was stained, so it is hard to tell.
 
TOOLS

[Dw07u]

You planning on painting that case now? Looks like the soda did a good job, why did it sit in water for years?