Sketch Level: Midnight

[Norcal]

I found this picture of a CMU wall that was mostly destroyed by an exploding compressor tank. Is this the one referenced above?

Thanks for posting that photo, it illustrates the immense power of compressed gasses.

 

[Metal-Marc]

Thanks for posting that photo, it illustrates the immense power of compressed gasses.

The guy ate beans for his last meal.

 

[Jim greengo]

One of my two air compressors has had an audible leak from the bottom of the tank for the past few weeks. I finally got ambitious enough to disconnect it from everything, lay it on its side, and take a look. Found a pinhole with a rust streak around it. Just to see if I could, I "successfully" repaired it by drilling it out, tapping a hole (into about 3/16" of fairly clean metal), and screwing a 1/4"-20 bolt into it with part of a used bicycle tire as a gasket:



Believe it or not, this is actually holding 120 psi. Although I'm neither brave nor stupid enough to stand in front of it at that pressure. Yes, I am going to reinstall the compressor, but just temporarily. I figure if it lets go while upright, the worst it will do is put a dent in my floor.

The reason I'm posting this here is, I am looking to get a new compressor, and figured I would upgrade to a 2-stage while I was at it. Current compressor is wired to a 30A double pole breaker, which is about 3 ft of 10-3 wire away from a wall plug (NEMA 30A, I forget which configuration offhand). There is about 5 ft of 10-3 SJ cord from the plug to the compressor motor. Current motor FLA (nameplate) is 17.2 @ 240V.

The compressor I am considering says this in the specs:

• 21.5 Full Load Amps, Recommended Breaker Amp Size 40, Recommended Wire Gauge<50 ft. 8 Gauge

Not sure why a 21.5A FLA motor needs 8 gage wire, or a 40A breaker, but I also am not an electrician. Changing the breaker, outlet, and SJ cord is easy. Upsizing the wiring between the panel and the outlet would be "intrusive."

Since there seems to be an impressive amount of knowledge and experience on this forum, I thought I would ask for opinions. Can I run this compressor on a 30A circuit? Will it kill me and all the neighbors if I try? Do I have to cut a holes in my wall to install 8-3 wire if I want to run this compressor? Have you already concluded from my compressor repair that I am too dumb to be left in a garage full of tools unsupervised?

Appreciate all constructive input.

MrFreeze

I'd say it's time to replace that grenade with a new compressor.

 

[Lassen Forge]

I don't even want to comment on this other than to advise you to turn it into a barbecue. Or a smoker. Cut that ******* thing in half YESTERDAY. I don't care how or why you repressured a fubarred and compromised tank, or how you "repaired" one little part with a bolt and inner tube gasket. Then defended??? FFS...

It doesn't matter if you *think* that was the only bad sopt in the tank. You willing to bet your life, and those around you, on a "I'm pretty sure it's safe"? Let me see your STI certs and inspection docs. Thats what the insurance company will want to see before they pay out on the accidental death and dismemberment policy. For your wife and kid who were talking with you out in your shop about Thanksgiving.

That tank - ain't worth dying over. If you dismiss it because, well, you think I'm being dramatic - then I'm not the fool. Sorry, dude.

 

[ArcReactorKC]

So could the sun! But your point is well taken...

MrFreeze

So I think you were using hyperbole but using the Sun as a reference to your exploding tank is not apt.

The sun has approximately 5 billion years of hydrogen left before it starts the process of star death. It won't explode then either, it'll start to decay and go through the stages of star death.

But don't worry before it "explodes" (goes supernova) it will have already grown large enough to consume the earth.

Source:

Will the Sun Ever Stop Shining?

The sun is a star that formed about 4.6 billion years ago. Scientists believe that a giant spinning cloud of gas and dust began to collapse due to its gravity. Much of the material that collapsed came together to form the sun. Gravity continues to create pressure, pulling the material that makes...

askanearthspacescientist.asu.edu

 

[Bert_]

I've run 5hp motors on #10 Romex.

It's not code compliant but the full load current values that the code calls out are extremely outdated.

I generally put 5hp 1ph motors on a 40 or 50A breaker. 30-60 amp breakers are the same price so there is no reason to undersize it.

 

[4x4Pete]

Not to reduce the serious nature of using a damaged compressed air tank, but wouldn't there need to be another fault or compromise that would cause a catastrophic explosion? I could see a tank blowing open a bad section of rot at the bottom but if it was bolted down, like it should, it probably would be scary as hell but not necessarily damaging to the surroundings. There would have to be another fault to cause a catastrophic explosion, which could happen to a "good" tank almost as easily. Pressure switch stuck on and relief valve inoperable, etc... You would think that if this was happening with any regularity a governing body would add regulations that would prevent it. Just like houses that explode from gas, there's usually several additional faults that end up with a bad situation. With all this said, no need to gamble, I myself wouldn't use it and make it into a fire pit or yard art and sell it. I have made fire pits from 3 leaky compressed air tanks rather than trying to repair them. The dome ends make great fire pits! I was just wondering what line of events need to happen to make a tank catastrophically explode.