|01-26-2009 01:01 PM|
I just came across this little incident on another forum and since this old thread was revived recently I thought some of you might find it interesting.
The fella that was telling what happened said his uncle had a small compressor that was about 20 years old and they had forgotten to unplug it and the tank let go on the thing during the night. He described the tank as "opening up like a banana peel" and going through the metal siding of their small garage where it left a hole big enough for a man to crawl through. They found the tank about fifty feet away from the building and the pump about 100 feet away, he said they could not even find the motor! He ended the story by saying he has become a big fan of hydo testing after seeing that!
While tank ruptures are not exactly an everyday occurrence they do happen and sometimes it can get real serious. Injuries and even fatalities are sometimes the result of these failures and property damage besides the compressor itself is likely in the event of a failure so it is a very good idea to treat these things with respect and DON'T TAKE CHANCES!
|01-18-2009 12:59 PM|
I've got a buddy that only runs his compressor when he wants to use it.
Having to wait for that ... what a pain!
I have a ball-valve shut-off on mine, so it stays at 125 PSI all the time. It runs very seldomly (if ever), and air is available any time I want it.
Think of air as "kinetic energy", and spend the time to find and repair any line leaks that you can. Doing so will save you money, time, and aggravation.
Spend the extra money on good quality couplers, plugs, teflon tape and hoses ... they'll pay for themselves over time.
|01-18-2009 12:31 PM|
|01-18-2009 08:59 AM|
|oldred||If that compressor is bleeding down to zero (or nearly so) every night you should find out why and stop it, probably a simple shut-off valve at the tank will do it. Having to refill a compressor tank from zero every day puts a tremendous amount of unnecessary wear on the pump because of the long run time and heat build-up, occasionally dropping the tank to near zero will not not hurt anything but it adds up fast. If this happens, for example, 250 days out of a year and takes 7 minutes to refill from empty that is about 29 hours of wasted hard run time per year not to mention the wasted power. The bigger problem though is the fact that the tank has to expand and contract through each of these cycles which will greatly shorten it's service life and as old as yours is it likely will not have a lot of time left anyway so you need to go easy on it. Most people don't realize that a tank undergoes expansion and contraction during discharge/recharge but it does, not much during the normal discharge/recharge cycle but all the way down to zero and than back up to pressure causes a lot of expansion/contraction which will eventually lead to tank failure due to metal fatigue. Obviously letting the tank drain to zero is a REALLY bad idea and you really need to address this problem as soon as possible, especially considering how old that compressor is.|
|01-18-2009 04:11 AM|
|metalmeltr||My dad has a 60 gallon cambell hasfeld 2 stage compressor that is probly 20+ years old and it works great. We had to change the pressure switch and magnetic starter a couple years ago but other than that it is all good. There are a few leaks in our air lines so it will bleed down overnight, but i usally forget to turn it off so it stays pressurized. If bleeding don the comressor is bad is using auto drains also bad. As far as tank explosions are concerned I have taken pop bottles both2 liter and smaller ones and drilled a hallf in hole in the cap put a valve stem in the bottle the fits snuly in the neck and the cap holds it in and presurize it as high as I can get it abuot 120 psi and poke a hole in it with a nail in the end of the stick andthe blast is like a shotgun and it ecoes in the suronding woods, the first time i did it i heldit and just poked the hole but now I stand back and whack it with the stick with a nail in it since my hand was numb after doing that. any way when i do ths the bottles can fly 20' and that is not with much pressure|
|01-17-2009 01:09 PM|
|oldred||That reads like so many I have seen in safety bulletins from years past, while fortunately it is not a common occurrence it does happen far more than most people realize. Of the one's I have read about and the two I witnessed first-hand most were related to attempting a repair which should of course NEVER, EVER be done! Both of the tank explosions I looked at were caused by rust/metal fatigue but repairs accounted for the largest number of the one's I read about. Sometimes these explosions involved injury and sometimes a fatality and I can only guess at how many close calls went unreported since unless an injury or fatality was involved it was not included in those bulletins. I remember one in particular where a large tank of about 200 gals at a sawmill blew the end out and the main portion of the tank body was found nearly 1/4 of a mile away!|
|01-17-2009 12:18 PM|
This story was in the Fresno Bee today. The net version is shortened a bit.http://www.fresnobee.com/updates/story/1136067.html try this again:
The air compressor tank had been repaired at this shop, they were testing it when it blew up. One man killed immediately.
|11-28-2006 07:26 AM|
|oldred||Just thinking, all this talk about tanks and service life might lead one to think that tank failure might be a major concern but in fact tank failure is rare in a normal shop situation even on old tanks. A tank's service life is determined by, damage from rust and abuse aside, the number of expansion/contraction cycles it goes through and under normal use the tank will far out last the pump so if the water is drained regularly and it is not damaged from accident or other reasons it should never be a problem. Draining a tank to zero pressure on a daily basis is abusing it and it just stands to reason that if you greatly increase the magnitude of the expansion/contraction cycles then the number of cycles will be decreased before it fails due to metal fatigue. If you abuse your tank in this manner then you very well may experience failure in a few years, maybe sooner, but if you maintain it properly then you probably will never see a tank failure even after many years. It is not uncommon to find tanks that are 20-30 years old and even older but I would strongly recommend pressure testing one this old if it is considered for use even if it is on a running compressor, just to be safe.|
|11-27-2006 08:28 PM|
Draining water does not significantly reduce the pressure and draining a tank down to about 75 PSI or so will not be nearly as bad as zero since the tank will still be expanded. This, BTW, is not just my opinion but is fairly well known fact and for examples I can give you a good one. Since this is hardly a problem with smaller tanks it was not a problem on mining trucks that use air starters and almost completely drain their tanks several times a day, that is until on one job we decided to use 60 gallon tanks to replace the smaller ones in order to increase the starter volume(bigger tanks help a lot here since this is a one shot affair that does not rely on the compressor). After a while the tanks began to develop the cracks that are common to a tank that has reached the end of it's service life but these tanks had been total discharged and recharged many times, just as if they had been completely drained everyday. These were the common medium duty tanks found on consumer air compressors and were charged to 135 PSI. Some of the larger mining trucks use much larger tanks of 80 gallons or even bigger with no problems but these are a lot heavier than you are likely to find on a normal shop compressor. I have sold and serviced air compressors for over thirty years and I have seen many tanks crack from fatigue and vibration and the ones with leaky systems that allowed them to drain frequently had a noticeably shorter service life. I never said that you would ruin a tank in a short time and in fact it may take a while for damage to appear, probably many years on a heavy commercial unit but for the common consumer units which are quite a bit lighter the cracks can appear in a much shorter time. Drain yours if you like but it's service life will suffer.
As an added note tanks which reach the end of their service life and fail from fatigue, whether in a normal time or accelerated from excess expansion/contraction, rarely do more than just develop cracks usually around a weld at the mounting feet or pump/motor brackets and do not present much of a danger. Tanks that have reached this point must be scraped and should NEVER be repaired by welding or any other means and to attempt to repair one can be extremely dangerous.
|11-27-2006 06:52 PM|
I have had close association with two long-time, regularly used air compressor systems. One was a body shop system and "Dan the Man" insisted that the water be drained daily, to a level that significantly decreased the pressure in the tank -- not dead empty, but it would take a few minutes in the morning to cycle up, probably 2/3 or 3/4 of the way down.
The other is a boatyard system that I am still around. The water gets drained 2 or 3 times a week and the compressor is shut off on Saturday afternoon unless customers are using it, in which case it runs all weekend and all week to the next weekend, sometimes 3 or 4 weeks in a row.
The first lasted many years til the dealer went out of business, and the second is still running. At least 25 or 30 years of life each...
The logic is sound, but practices differ I guess.
|11-27-2006 06:36 PM|
|oldred||Over the years I have heard many stories about those bottles and a couple of them I know are fact, most probably are. One happened to a friend of mine who was a railroad employee that dropped one off of a rail service truck and he insists they tracked that thing over 1200 feet bouncing between rails before it stopped, this fellow is a no BS kind of guy and I have no doubt what he said was true. Another was in a safety bulletin, it went through a light metal garage door, a chain link fence, took out and awning and a picnic table before winding up in a swimming pool about 150' from the garage where it started it then spun around until the pressure was finally gone. Yep those things can create some excitement!|
|11-27-2006 04:51 PM|
|weirdbeard||Funny that you tell that story Farna. I was just watching a show last night called myth busters and they were testing that old (myth). They got very similar results.|
|11-27-2006 01:13 PM|
|farna||I'm USAF. Had to go repair a hangar wall that an oxygen tank went through in the mid 80s. Kid that started to move the cart without checking reportedly got a severe tongue lashing and nearly had a heart attack as he watched the tank skid across the floor between two fighters before it bounced up and went through the wall, across the parking lot, and sunk about a foot in a dirt bank. Went right through the middle of an empty parking space against the building, with a car parked to each side. Talk about lucky!! That tank traveled a bit over 100' and still had the energy to embed a foot in relatively hard packed dirt. Now if it had hit him on the way out, or the regulator that popped off had hit someone/something... I don't recall what happened to the regulator, but the lightest thing will go the furthest fastest. Throw a rifle shell in the fire (well, no, don't!!) and the bullet will likely stay in the fire. The lighter shell casing is what will launch and be dangerous!|
|11-24-2006 10:46 PM|
It would be interesting to know how many times the wisdom from hotrodders members has helped people go about working more safely and helped avoid harm. This is truly a great site.
|11-24-2006 09:12 PM|
|weirdbeard||Exploding tanks have always been a lil fear of mine. Like a bomb just waiting to go off. So many people neglect to maintain there compressors and it just makes me cringe. But not as much a somebody knocking over a oxy/acetylene set up onto concrete.|
|This thread has more than 15 replies. Click here to review the whole thread.|