Air compressor explosion

[Bencrx91]

http://www.cbc.ca/news/canada/ottawa/quebec-man-dies-after-losing-leg-in-weekend-explosion-1.2457103

No much details in news, but how much rust could cause such an explosion?

I use my 60 Husky 60gal compressor once every month or so, and rarely drain it (like a few times in 5 years), I drained it today and maybe 2 cups of rusty colored water came out... is this considered dangerous or just normal ?

Thx.,
Ben

 

[djjsr]

Wow. I really find it hard to believe that a rusty tank would cause an explosion. I had an old compressor with a rusty tank and it just got to the point where it leaked so bad, it wouldn't hold hardly any pressure. Certainly not enough to blow the tank.

Pure speculation, but I'm guessing either a faulty limit switch accompanied by a faulty or missing pop-off, or a repaired tank, welded by someone not qualified.

 

[jomobco]

Rusty pressure valve is my guess. I bet it kept running.

 

[redprmr2]

These can happen when the walls of the tank become to thin to hold the psi. These is the why draining the tank is a good thing to do.

 

[G_P]

That must have been some SEVERE rust and a stuck pressure switch. Tanks usually develop a pinhole which starts leaking. They dont often blow up like a bomb.

 

[marinusdees]

Air compressor tanks don't explode, they rupture Big difference. They are not(normally) filled by an explosive mixture. I yours is, get another life, you'll need it. A rupture will scare the s out of you but will NOT produce any shrapnel, let alone any rifle bullets. If you don't believe this, you didn't take HS physics.

 

[Jrican]

It's unlikely that the blowout valve or the pressure switch alone would cause this problem.
A pump with an 8.5:1 compression ratio could not pump much over 125 psia (110 psig).
12:1 compression ratio gets 177 psia etc. (Boyle's law)
Most tank are tested to well over this when they are manufactured. however if the tank was made week in someway, such as being dropped, badly scratched, rusted etc., it will no longer hold the pressure it was designed to.

 

[mechx]

How can an air receiver tank explode?
During operation, deposits of lubricating oil tend to build up in the line supplying compressed air from the compressor cylinder to the air receiver. As the diameter of the supply line decreases, the already high temperature of the compressed air rises further to a point where it is possible for the contaminant to ignite.

Sparks are then carried into the air receiver where oil from the compressor, which is often present as a mixture with air in the air receiver, burns explosively. As the pressure relief valve is not designed for such an event, rupture of the air receiver vessel is likely to occur. In other air compressor accidents, static electricity sparks have also been identified as a source of fires and explosions

 

[mechx]

I found that at "work safe Victoria"

 

[CNGsaves]

Air compressor tanks don't explode, they rupture Big difference. They are not(normally) filled by an explosive mixture. I yours is, get another life, you'll need it. A rupture will scare the s out of you but will NOT produce any shrapnel, let alone any rifle bullets. If you don't believe this, you didn't take HS physics.

Obviously you have NOT done any research on the internet as whole, let alone research here on GJ of prior AIR COMPRESSOR TANK explosions, or rupture if that's what you want to call it !! Your above response is clueless and irresponsible.

Many rusty tanks have exploded over the years, INCLUDING injuring people and destroying property. Often welded seams on bottom of tank become weak and blow open like an aerosol can put into a fire.

True terminology is PRESSURE VESSEL when you are referring to pressurized air tank. Each tank has manufacturer's tag that contains WAP (working air pressure) and MAP (maximum air pressure). Sometimes a faulty compressor component may fail and continue to pressurize the vessel until it explodes.

If you're offering to "prove your theory" tanks never explode, I'm sure a GJer can arrange to send you an old RUSTY horizontal 20 gallon air tank so you can keep it pressurized with 150 ps and put tank right next to where you sleep each night !! "If you're feeling lucky kid" then crank up compressor regulator to 175 psi and remove the PRV (pressure relief valve) !!!

 

[Fixnair]

Sorry to disagree with you marinrusdees. The explosion may not be caused by heat but pressure causes the same effect. I've seen too many of them in my work the last 50 years. Not small pieces of shrapnel but large ones. Picture a 25 horsepower compressor, separated from the base & motor flying 300 feet away from where it was bolted down.
There is a tremendous amount of energy stored in an air receiver. You guys need to excercize a great deal of caution when working around it.

 

[tdkkart]

The concussion from the air blast alone when a tank comes apart is enough to cause serious injury even if the tank does nothing but hinges up like a door. And what about the items that are sitting between you and the compressor when that blast of air hits them. Even a beer bottle hit by that much air will kill you in a second, imagine what a can of nails would do. Remember the pics from the Boston bombing??
I have seen pics of the whole corner of a building blown out by a compressor(80 gallon upright) with a bad pressure switch. The compressor was bolted down, never moved, and didn't throw shrapnel, just peeled open like a can of Pillsbury muffins. The blast from the sudden release of air blew the walls down.

 

[jaker10]

A little off topic, but is there any danger of having an air compressor in a unheated space ? Mine is a 60 gallon and it pumps to 150 lbs. and its 2 degrees right now. It is only 2 years old and drained when ever I use it, but I always back away when it fires up. Like backing away would do any good if it blows. Just thought I'd ask.

 

[Bull]

A little off topic, but is there any danger of having an air compressor in a unheated space ? Mine is a 60 gallon and it pumps to 150 lbs. and its 2 degrees right now. It is only 2 years old and drained when ever I use it, but I always back away when it fires up. Like backing away would do any good if it blows. Just thought I'd ask.

I'll be interested to see what those who have actual knowledge say.

In my view, the only thing an unheated space is going to do is to increase the moisture level in the tank and therefore require diligent draining. Cold air inside the tank before you fire it up; compressed air entering is hot; hot and cold air together create moisture.

But I sucked at science in school so that could be a crackpot misunderstanding.

 

[rlitman]

Cold air holds less absolute humidity at the same RH. So I would expect the moisture level in the tank to be lower with the same amount of use. That confirms the fact that I drain less water in the winter than the summer.

If water is allowed to freeze in the drain ****, it could potentially rupture it, although I have not heard of freezing water causing a compressor failure.

As for a pressure vessel failure peeling apart a building. To be clear, it is not a surprise that walls were blown down. The pressure wave over such a surface area can make for an enormous force. Being smaller than a wall, a human would experience much less force. I leave it up to the Mythbusters to determine how much of that would be lethal.

There are many anecdotes about failing compressor tanks. One posted here I believe was a failure at a seam. That is not surprising, as it is logically a weak point. Also, the walls of a tank are generally thinner than the end bells. That is one reason I prefer a vertical compressor. The part most exposed to water and corrosion is the end bell, and not a body seam.

 

[galute]

I'm not an air compressor expert per se but I do a lot of pressure testing. I've never seen any specs requireing adjustment to pressures due to ambient temps. Always use the same pressures no matter if it's 100 or 0 degrees and we test very high pressures at times in excess of 3000 psi.

 

[Super Mech]

A compressor explosion happened at a shop near me last week. The compressor was located in a separate building about 25-30 feet from the main shop. The owner and his son along with their dog where in this separate building getting changed to go to work in the shop. The compressor was located in the basement of the secondary building. The place is(was) made of stone and concrete at least 90 years old. The compressor blew up and completely leveled the place. The father was in critical condition with various broken bones, I belive the son had broken legs and maybe an arm, the dog didn't make it.

 

[brianpgriset]

I'll be interested to see what those who have actual knowledge say.

In my view, the only thing an unheated space is going to do is to increase the moisture level in the tank and therefore require diligent draining. Cold air inside the tank before you fire it up; compressed air entering is hot; hot and cold air together create moisture.

But I sucked at science in school so that could be a crackpot misunderstanding.

Start Reading Up On Brittle Fracture. .

But No YoU Have Nothing To Worry About.

 

[djjsr]

..... but is there any danger of having an air compressor in a unheated space ? Mine is a 60 gallon and it pumps to 150 lbs. and its 2 degrees right now.

What oil are you using?

 

[NHBandit]

Air compressor tanks don't explode, they rupture Big difference. They are not(normally) filled by an explosive mixture. I yours is, get another life, you'll need it. A rupture will scare the s out of you but will NOT produce any shrapnel, let alone any rifle bullets. If you don't believe this, you didn't take HS physics.

Tell that to the dead guy professor.... Personally I'd like to see the facts of how & why this happened.

 

[BellyUpFish]

Holy smokes.. Sounds like a good reason to get the compressor outside...

 

[djjsr]

Personally I'd like to see the facts of how & why this happened.

Me too!

I've always been fascinated by failure analysis. It was part of my job for decades.

 

[JakeKohl]

It's unlikely that the blowout valve or the pressure switch alone would cause this problem.
A pump with an 8.5:1 compression ratio could not pump much over 125 psia (110 psig).
12:1 compression ratio gets 177 psia etc. (Boyle's law)
Most tank are tested to well over this when they are manufactured. however if the tank was made week in someway, such as being dropped, badly scratched, rusted etc., it will no longer hold the pressure it was designed to.

Interesting...I'm not sure this is a correct/direct application of Boyle's law, but I never really considered the minimum headspace in the cylinder and how it would limit the ultimate amount of pressure it could achieve.

 

[Hencini]

A little off topic, but is there any danger of having an air compressor in a unheated space ? Mine is a 60 gallon and it pumps to 150 lbs. and its 2 degrees right now. It is only 2 years old and drained when ever I use it, but I always back away when it fires up. Like backing away would do any good if it blows. Just thought I'd ask.

I used to have my compressor in my uninsulated garage in WI. I forgot to turn it off one time and it must have cycled on during the night, but with the temps as low as they were (below 0), the piston was unable to move, so the load from the motor tripped the breaker. In the morning, I couldn't figure out why the garage door opener wouldn't work.

Once I realized what had happened (it took a couple times flipping the breaker, then trying to figure out what that buzzing noise was) I was worried that the motor had burned out, but it was fine. Good thing the breaker tripped when it did.

 

[jaker10]

What oil are you using?

IR all season oil.

 

[lisiecki1]

I have a friend that was inspecting some compressor lines at work last year. All of them looked to be in good shape. As he was walking past one of the lines, which was at head height, it popped and sent rusty shrapnel into his face.

Good thing he was wearing safety glasses. He looked like two-face (batman reference) for a good couple of months afterward.

Sudden releases of pressure can be very bad.

 

[b-body-bob]

The concussion from the air blast alone when a tank comes apart is enough to cause serious injury even if the tank does nothing but hinges up like a door.

I know a guy who got too close to a truck tire, in a cage, while inflating. It blew the safety ring off and the concussion knocked his teeth out and ruined his hearing.

 

[fomocoforrester]

These can happen when the walls of the tank become to thin to hold the psi. These is the why draining the tank is a good thing to do.

In my view, the only thing an unheated space is going to do is to increase the moisture level in the tank and therefore require diligent draining.

I'm not sure draining is going to make much difference to the rupture risk from corrosion.

Even with an auto drain or continuous blowdown - the tank is never going to be dry inside and it more than likely have a puddle of water in it where it can't completly drain because of leveling or weld penetration around the drain boss.

So the low point is going to corrode just as fast as if the tank were full of water - and on the principle that a chain is only as strong as it's weakest link - the tank is equally likely (or not) to rupture.

 

[Stuart in MN]

I've seen a small home air compressor that ruptured. Apparently, the pressure switch failed so it kept running, and then the relief valve was rusted shut. Fortunately, no one was in the garage when it failed, but the shrapnel from the tank did a number on the car that was parked next to it. What was left of the tank itself was pretty much turned inside out, it looked like a steel potato chip.

 

[Bull]

If you guys keep sharing examples, I am going to be too afraid to use my compressor and switch to all electric tools. Please stop!

 

[Stuart in MN]

I wouldn't get too scared. I think the main things to take away from this discussion are to 1) maintain the compressor properly and 2) unplug it when it's not in use.

 

[BD1]

Air compressor tanks don't explode, they rupture Big difference. They are not(normally) filled by an explosive mixture. I yours is, get another life, you'll need it. A rupture will scare the s out of you but will NOT produce any shrapnel, let alone any rifle bullets. If you don't believe this, you didn't take HS physics.

Check this out. http://weldingweb.com/showthread.php?48232-Stay-from-those-old-compressor

More reading.
http://weldingweb.com/showthread.php?273691-Compressor-explosions&highlight=air+compressor

 

[MoonRise]

If you guys keep sharing examples, I am going to be too afraid to use my compressor and switch to all electric tools. Please stop!

Respect the power that is stored in the compressed air, and maintain your compressor and lines.

fer instance:

1 hp = 746 watts = 550 ft-lb/sec

So if a little compressor with a little 1 hp motor ran for two minutes to fill up the tank before shutting off, then the motor ended up inputting

550 ft-lb/sec x 120 sec = 66,000 ft-lb of "work" done

Let's even throw in some efficiency factors of 80% for the electric motor and 80% for the air pump.

66,000 ft-lb x .8 (motor efficiency) x .8 (pump efficiency) = 42,240 ft-lbs of "work" or "energy" available.

So, thinking of it in another way, in those two minutes that the electric motor was running, it could have lifted 42,240 lbs one foot into the air (geared down or reduction pulleys or whatever).

Or 21,120 lbs lifted two feet into the air. Etc, etc, etc.

Jumping into SI units for a moment, where work=energy is measured in joules, we have (1 ft-lb = 1.4 J) 59,136 J.

Which is more energy than the muzzle energy of a 'elephant gun', about the energy contained in the combustion of 1 gram of gasoline, more than the energy contained in 1 gram of TNT, about the energy in a car moving about 25 mph, etc, etc, etc. But less than the energy contained in a 280 calorie candy bar.

http://en.wikipedia.org/wiki/Orders_of_magnitude_(energy)

Drop that weight suddenly and it can make a rather big smash/crash/boom.

That's a rough measure of how much "energy" has been input into the 'system' and is now stored in that compressed air in the tank.

And that's for our example 'little' 1 hp electric motor filling the tank in 2 minutes.

You have a bigger tank with a bigger motor that takes longer to fill up? Then even more energy is stored in that tank full of compressed air.

Which is 'good', because we can then use that energy from the compressed air to do some useful things, like turning it back into some sort of mechanical work like an impact wrench or a die grinder or whatever pneumatic tool you want to use at the moment.

But if that energy in that compressed air somehow is released 'instantly' and in an uncontrolled and unexpected manner (such as a tank or pipe suddenly bursting), then there can be various negative effects. Ranging from a need to change the shorts, to a need to clean up or repair broken items (damage to items), to a need for medical attention (injury), to a need for a mortician (fatality).

Respect the energy that is contained in compressed gases and maintain the equipment.

Most of the time, tank or metal pipe failures are on the more 'graceful' end of the failure spectrum. ie: a leak develops.

But not always. Sometimes, the item releases the compressed air rather suddenly and zips/peels/splits open rather forcefully and can launch or propel items (including the tank or other things in the vicinity) forcefully.

Respect and maintain.

 

[mikegt4]

Sometimes, the item releases the compressed air rather suddenly and zips/peels/splits open rather forcefully and can launch or propel items (including the tank or other things in the vicinity) forcefully.

Respect and maintain.

X2
Last year a co-worker had his 30 year old compressor split apart when he was adjusting the air pressure in the tires on his NEW pickup truck. It was on the other side of the truck in his garage when it went off. It flew up and hit the ceiling then dropped down on the trucks hood and then fell to the floor in front of the truck. 30 seconds before he was right next to it. His hearing was impaired for a few days and insurance covered the damage to his new truck. The tank was pretty rusted inside. The good part is that I got the 3hp old school, made in the USA, motor off of the compressor.

 

[Bull]

I drain my compressor about once per week. My lines consist of a rubber hose.

Should I replace the pressure relief valve, or take it out to examine it?

Should I leave my tank empty? I currently leave it filled and turned on. But tonight when I go out there to feed the cat I will be switching the thing "off," that's for sure!

 

[rlitman]

The pressure relief valve has a pull ring. Don't pull on it without wearing hearing and eye protection.
You should test it annually, just like the pressure relief valve on your water heater.

 

[koditten]

There should be a pull ring on the pressure relieve valve. Give it a quick tug until a small burst of air is vented. It should pop back in and shut off the relise of air.

The pressure reliefe valve is supposed to "lift" when the pressure of the tank exceeds the setting on the relief valve, thus vent and prevent the tank from gaining any more pressure. These valves should really be called excessive pressure relief valves, after all thats what they do.

If you pull on this ring and can not make the valve vent, the PRV is stuck! This is bad and requires the PRV to be replaced!

I can't count the times I have been inother people shops and walk over to the compressor and give PRV ring a quick pull. I usually get the "what the hell are you doing?" phrase. After explainint that I did them a favor and why, I usually get a healthy thanks.

I have encountered compressor tanks that have had the PRV plugged with a pipe plug. Home use compressors have a pretty "cheap" PRV. When they go bad and won't seal, some people just cap them. This is another very bad thing!

With all that said, I still rank a compressor tank explosion and failure up there with the chances at winning the lottery. I've heard of more people winning the Power Ball than tank explosions.

Drain it once and a while, check the PRV and don't **** with the pressure switch to get more pressure and the risk of a tank explosion is reduced almost to zero.

Its good to be aware, but don't lose sleep.

Later

KO

 

[R6 Racer]

I'm not sure draining is going to make much difference to the rupture risk from corrosion.

Even with an auto drain or continuous blowdown - the tank is never going to be dry inside and it more than likely have a puddle of water in it where it can't completly drain because of leveling or weld penetration around the drain boss.

/QUOTE]

I'll start with full admission... I'm no expert by any standards!

As for the never being dry or drying out, wouldn't the warm air produced by the compressor dry the little dampness that's left in the tank after draining?

My routine... I drain my compressor after every day of using it & I turn the power to it off right after. The only time I have power going to it is when i'm using it.

PS...
1) I only have to use a rag to collect the moisture that I get from it.
2) I have my compressor in a place in my garage that shields my entire working area from it.

Steve

 

[koditten]

rlitman:

Thanks for that tip. It can be a pretty loud air blast.

In addition, do the test when the tank is at full operating pressure. Doing the test with only 10psi on the tank does nothing.

KO

 

[rlitman]

It can be pretty loud, and it can spray whatever **** is in the tank along with the air. Usually a rusty oily fog.
Oh, and once you pull the ring, the airflow will generally not let it snap shut until the pressure in the tank has dropped quite a bit, although you can usually pop it back in with your finger.