HF pressure tank testing

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J

Jarheaded

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Joined
Nov 30, 2007
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1,264
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Fairfield county, CT, USA.
So far, all tests have failed miserably. We hooked the pot directly up to the compresser, took off all relief valves and gauges that could fail, and use a high pressure hose without any quick connects or anything that might fail before the tank. We got the compresser up to max 180# and absolutely nothing happened at all. there were some suggestions made about using lead to create a small hole, but I felt that usually won't happen under normal circumstances. I am thinking of some way to hook it up to multiple scuba tanks and see if we can get a reaction. I know better than to ask the owner of the local scuba shop for his compresser. But for now, I guess we will have to keep using our tanks in relative safety. If you can think of some scenerio that might cause a tank to rupture, please let me know. I would hate to use the small hole idea.[}:)]
 
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Thats actually great news for us. The higher you have to go for a failure, the better. The most accurate results would be from a real world test, meaning no holes. Hopefully we wouldn't be poking holes in our tanks.

Thanks for the update and keep us posted on any results.
 
Something about your post made me pause, then it hit me...

When I ran the Fire Extinguisher Maintenance shop, fire extinguishers were hydrostatic tested with water, a protective cage was mandatory. You could still get shapnel...

Water not air was used. I imagine OSHA has a lot to say on this. Check your local FD or Extinguisher Repair Service and see about testing that pot with a pump made for testing high pressure...

Safety 1st, pressurized tanks are real bad boys...
 
Well Shanon, I guess you could say that I am trying to exceed in failure. There was a rumor on one of the forums stating the tanks were not safe to use in the way we do. Supposedly, the tanks fail if held above 60# for any length of time. I am bored and am normally blowing up something somehow, I figured I would try this for a laugh. We will be filming all attempts, but with no explosion, they are pretty boring. I hope this doesn't confuse you more.:)
Steve, I am trying to narrow it down to the weak spots. So, I will continue to add the usual parts back on until something fails and hopefully does it in a massively violent way. Better to try to do it than to do it without trying.
Johnnie
 
Why are you wanting to see when it fails? It is rated to 80psi (at least mine is) which really means it should hold more. But why? I cast PR with 25 psi and alumilite is cast at 60 psi(if I remember correctly, maybe less). Whatever you do, be careful.
Do a good turn daily!
Don
Originally posted by jwoodwright

Something about your post made me pause, then it hit me...

When I ran the Fire Extinguisher Maintenance shop, fire extinguishers were hydrostatic tested with water, a protective cage was mandatory. You could still get shapnel...

Water not air was used. I imagine OSHA has a lot to say on this. Check your local FD or Extinguisher Repair Service and see about testing that pot with a pump made for testing high pressure...

Safety 1st, pressurized tanks are real bad boys...
Click to expand...
 
John,
You must be kidding. If I were to tell them that I ws doing this, they would give me a headache with all their talk and no action. I have a safe area that I am using for this and if you look at my profile, you may feel that I am qualified to play, or at least willing to play.[}:)]

Don, I am doing this simply because I bought some extra tanks and have way too much time onmy hands. I guess that is it in a nut shell.
 
Most of the complaints on the Yahoo casting group were about the clamps failing not a pot rupture. And on closer research of the people complaining- they were trying to clamp the lid closed while applying air pressure to the pot.

I asked my brother (a bona-fidey rocket scientist) to look over the parts and he just laughed and said that if a catastophic failure of a single clamp occured, a rather large portion of the seal would be unsupported and one would have a "burp", if I remember what he said correctly. The "burp" would vent all of the pressure more gently, although abruptly, than if you pulled the safety release ring on the overpressure valve.

He did point out though, that at the (I believe he computed it to 80psi) maximum rating the internal force exerted upward on the lid was something over 7000 pounds, which is 3 & 1/2 tons. So still nothing to sneeze at.

He also said that they(his company) use an overpressure value of 5/3(166%) of a vessels rating as the standard for what a pressure vessel must be able to withstand.
 
Originally posted by Jarheaded

...I am doing this simply because I bought some extra tanks and have way too much time onmy hands. I guess that is it in a nut shell...
Click to expand...

J-Dog, you are absolutely priceless! ROTFL about this whole post.

Only a true Marine would call something NOT blowing up a failure.

Dude, sometimes I don't know what I'd do without you on this forum! Keep up the good work, and don't kill yourself..erm...unless it's in like a really spectacular way that I can read about in the news.

"A man was killed today in shed behind the local scuba shop after setting up what appears to be homemade bomb-building equipment, and then shooting at it with a large handgun. Authorities are still trying to determine a motive..."
 
I recall this discussion before about using Mason or pickle jars and vacuum.
When it goes with a vacuum, you get an implosion, then the following explosion of pieces...
I believe it's Newton's 3rd Law: For every action, there is an opposite and equal reaction.

So, hook a vacuum pump up to your pressure pot, apply vacuum until catastrophic failure occurs...
 
With glass or more frangible materials used for HIGH VACUUM chambers, the "explosion" is from the elastic and reflective motion imparted in the broken glass. Metals just crush.

You can use glass with relative safety in low vacuum situations, look up bell jars.
 
I don't have a vacuum pump. Anyone want to loan me one. I will ask that you not hold me resposible for the possible damages that will definetly occur. Does anyone know where I can buy one at a decent price because I don't think anyone is going to loan me a pump to blow up. Hey Glass, all that made complete and total sense to your brother in law, but pretend that you are talking to someone that isn't a rocket scientist. some of what I could figure out of what you said was that I need a valve that can apply approxiametly 500% of the rated pressure since I already did better than 200%. And I also figured out that if this tank does blow, it will be spectacular.:)
Karl, the owner at the scuba shop won't let me play with his toys since I tried something else a couple of years ago and he got very nervous. Also if you do read about me in the paper and they are looking for a motive, you can tell them that the motive was to fill in some spare time and I may have made a slight mistake in my calculations. OOOPS
To all, I decided to just add parts that would normally go on a pressure pot and not add anything else to it like a hole. The one thing that I will not be putting on is a pressure relief valve, but I don't have one on my tank anyways. Something is going to fail so I will start with the stock parts and then start adding better quality as things fail. This is basically a test so we know what not to do and are not tempted to do something experimentally. I do have a good amount of training with explosives and I am only using compressd air so this one is different. I want to see something fail besides this test. As much as I am making light of this, I am taking strick precautions and again, I have the training. I am wearing a flack jacket while doing this and have some serious blast sheilds.. I am also doing this in an area of my property that is in a valley so any shrapnal will either hit the ground around it or the sheilds. Safety is a serious issue as I am not doing this alone, and I have to worry about the others not getting hurt. That is above and beyond anything else. I will make jokes about it, but I am not trying to kill myself....But who doesn't like a big boom?:D[}:)][}:)][}:)]


No detcord or c4 allowed in this test. Sorry Tow
 
Originally posted by Jarheaded

I don't have a vacuum pump. Anyone want to loan me one. I will ask that you not hold me resposible for the possible damages that will definetly occur. Does anyone know where I can buy one at a decent price because I don't think anyone is going to loan me a pump to blow up. Hey Glass, all that made complete and total sense to your brother in law, but pretend that you are talking to someone that isn't a rocket scientist. some of what I could figure out of what you said was that I need a valve that can apply approxiametly 500% of the rated pressure since I already did better than 200%. And I also figured out that if this tank does blow, it will be spectacular.:)

Snipboomy
Click to expand...

The pot should be "SAFE" to approx 133psi if HF used the same standards as my brother's company. I, myself don't plan on using that much pressure.[:I]

To make your test more realistic you could shut the pot, apply pressure, leave it at pressure for some time then dump the pressure and pop open the pot, then repeat. Going through the steps as if you were really casting, and making a mark on a tallyboard or journal for each repetition.

You can find vacuum pumps listed on eBay. I refrained from bidding on a 2 stage Robinair vacuum pump, that went real cheap, and could kick myself.
 
I knew a guy who decided to make some high octane beer so he substituted regular yeast with champaign yeast. The bottles he used were of the lower psi rating and all he did was shread his beer bottle cases and stick glass shards in the drywall in his basement...This blowing up a harbour freight paint pot sounds like the same kind of fun.....I would think that the pressure relief valve(s) are whats rated @ 166% of the rated pressure. The pot would probably take a lot more persuasion without the reliefe valves installed. If these pots are made from mild steel, the tensil strength should be at least 50,000 lbs/inch.
 
this has been a big disapointment to me so far. I have trashed 2 pressure relief valves(factory units are crap and the metal actually breaks) and 1 factory gauge failed after being brought up to 140#. I will keep trying, but if I don't get some satisfaction soon and have something to actually be worth filming, I may have to try Scratchy's idea. I am also considering trying it with a little more heat applied as I am doing this in about 35 degree weather. maybe I should try replicating the temperature of say Texas, and stick it in an oven at 200 degrees.:D[}:)] No matter what, I am going to keep trying until I suceed in making this pot blow up in a highly entertaining and property damaging way.[}:)][}:)][}:)]
 
I hope you survive your endeavors.

Thanks for relieving my concern about not having a pressure relief valve on my unit. My compressor can't even get up to 140#.

GK
 
Lee, I don't think safety glasses are going to help much.
Myth busters won't do this because there is no myth, this is just fun. Besides, they want to use all kinds of safety stuff that I find excessive, like safety glasses.
I have never seen anything knock a clamp off or even come close. And finally, If you are casting at 150# and you drop your tank from 4 feet, you let me know what happens....LOL
 
I think you might need more than safty glasses if you were to knock it off your bench and it was to go bang. Last year a farmer in the next town was filling a spayer with air and it killed him when the tank let go.
Bob
 
Bob,
Are you trying to say that I may need to use some caution while I am doing this? I think I should get out my aluminum foil and make a suit out of it for protection.:D What is the safety factor of my Ray-Bans anyways. With all the damage that I have been able to do so far, I may as well be wearing a bathing suit [:0]. I think these tanks are pretty well made overall, except for the relief valve--JUNK--I personally will never use a factory one again.

Tomorrows test if it stops raining. We are going to hit max pressure(180#) on the tank and my son (qualified expert rifleman) will shoot one of the clamps off the tank and we will see what happens. He has been warned that he is not allowed to hit the tank and he won't.
I'm not sure which is more dangerous, the attempt to blow up this pot or a bunch of Marines and cops standing around getting frustrated that we have nothing at all to watch except a pressure tank doing the same thing that my other ones do except they are at least making a casting of something [|)]. Maybe I should be mixing some Alumilite and at least cast some worthless wood while this is going on. I think my biggest fear is ruining a mold that Gadget made(he does nice work). (This testing and promos alone should be worth something:D.) With all these cops that are starting to show up to watch this happen(friends and friends of friends) maybe I can get a donut shop to sponsor this.:D[}:)]

Disclaimer--- This is all just my opinion and nothing should be taken as a reason to not purchase these tanks. If anything, again my opinion, I use 3 for casting and am very happy with them and obviously, I can't seem to be able to destroy it under normal circumstances. But I am far from done.
 
Paul,
Are you saying that I may need to hit 50000psi to make this thing blow? I will need some serious hoses to hit that pressure. This may start to cost me money and lots of it. 1 bullet= 50 cents. If it comes to having to put a hole in it to make it fail, it will be a long ways down the road. I will never trust this pot for casting, so a last resort will be drastic and exciting for me. I might even go the direction that Tow suggested, or something like it.
But for now, I have not exhausted all the possible weaknesses thet this testing has to offer.
 
THE TESTING HAS BEEN SHUT DOWN
Due to an accident while attempting to cause a failure in the pressure pot, all testing is being put on hold. An air line connection failed and 2 of my friends were injured due to it. Several stitches and a lot of bruising later, I have to put this on hold. I thought that we had taken every precaution while doing this and I neglected to consider the lines that were leading out to the area. The temperature has been going from 50's to 20's and this may have weakened a line. I am responsible for 2 of my friends getting hurt. This was a test to try and get a pot to fail. I think that these pots are not going to fail with the modifications that we do. When the weather warms up and I can continue this safely, I will. But I am sorry for the injuries that I have caused and will stop until proper safety procedures can be implemented.I wish I had that part on film just so I would remember that there is more to consider dangerous than just the pot, but I don't think that I will forget anyways. The camera was aiming at the pot when all this took place. The good news is that everyone will be okay and I'm not getting sued. This just goes to show that even with no less than 6 people with experience in demolition, just something as little as an air line can cause damage even when it has been inspected.
Lee, I should have asked you to come down and watch(from a distance) just in case.
 
Thank God they will be ok.

Running full pressure over numerous attempts and temperture changes, sounds like premature hose failure.

I know you don't plan on stopping, so here's some advice...

Might I suggest using copper or iron pipe with two (2) stubb hoses.
(stubb hose to pot and 1-to compressor) use Aircraft Quality Hose, steel jacketed for stubb hoses.
Secure pipe to something solid. Ensure people are protected/shielded from compressor and piping connections.

Are you draining hoses and compressor between tests? Moisture from heated air will cause all kinds of grief...
 
I have to admit that I did slip up on some precautions. Next time will be warmer weather(late spring) and all hoses if I continue will be made from braided stainless. I also am not going to run 400' of hose, the compressor will be moved a lot closer to the site and all lines will be encased. I don't know at this point how much more I am willing to risk. My safety is not an issue, but others got hurt due to my mistake. If I continue, it will be done alone, no innocent bystanders. I really felt like hell when I saw what had happened. It might not be worth it. The whole thing was to make the pot fail and that wasn't going to happen without a lot of help from outside sources. Might have to put this one on the same list as : Make sure to unload before cleaning.[B)]
On a positive note, both guys were here tonight and do want to continue. I really have to think on this one.
 
I really hate to chime in here, but I feel I have to. Please, please stop!

As I was reading through the thread, I had a huge sense of foreboding, which culminated when I got to the page about the accident...You've just discovered something - no matter how well prepared you think you are, there's always one more thing that you might forget. You got lucky, this time, in that no-one was hurt - what happens next time? A pin hole leak in a ridiculously highly pressurized hose can sever appendage - and your pressure tank could end up turning into a rocket if your pressure release valves are compromised...

If you need to see a big bang, turn on Mythbusters...or wait until July 4th for some fireworks...but please don't end up winning the Darwin awards because you wanted to see what happened when you dangerously exceed maximum safety precautions!

There, I said it. Now my conscience is clear! :)

Andrew
 
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Johnie,

Let's think about why you started this project. Was it for the bang or to find out if the pot was safe doing what we do? If the latter, then you have proven it safe under any conditions we might use it in. If the former, get your C4 and be done with it.

In either case, there is no reason to continue with this thread of testing and risk more injuries.

Stay safe. You and your friends!
GK
 
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