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Anyone Ever Built an Air Tank?

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  • #46
    Originally posted by lanceman73 View Post
    150 PSI is nothing. If that tank explodes, it'll just crack a seem and leek out.

    Thanks,
    Lance
    I saw a portable air tank explode on my dads leg. He was in the hospital for a week. The tank had a crack about 12 long in the welded area and opened right up against his leg...Bob
    Bob Wright

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    • #47
      Originally posted by lanceman73 View Post
      So, you fill a air tank with 15 psi. Then you fill another tank with thicker walls, it's still the same. I've worked with hydraulics for a long time. 150 PSI is nothing. If that tank explodes, it'll just crack a seem and leek out. There will be no explosions at all. Look at gas cylinders, 2500 PSI, stored on service trucks. There is no problems with that. Still, no propane tanks in my opinion, should be used for compressed air. They are too fat in diameter. I'm not an engineer, but happy with my homemade setup.

      Thanks,
      Lance
      You are most certainly correct: you are not an engineer

      Air, or other compressible fluid (gas) is NOT hydraulic fluid. Compressed gasses store much, much more energy than liquids. The stored energy is available to do a great deal of damage in the case of a failure. Rough rule: 40gal of air compressed to 100PSIG is equivalent to one stick of straight dynamite (if you ar about to respond 'no one here knows what a stick of dynamite is', you are missing the point: even if you have never used it, you wouldn't hold a tin can with a stick in it while it was detonated, nor would you want it in your home.)

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      • #48
        For the Record...I built my own compressor tank

        Actually my dad had me make a replacement tank for our 1.5 HP 2 cylinder WW Grainger compressor. The twin hotdog tanks rusted out and they were very thin metal wise. My dad had purchased 8" weld on cap ends from a pipe supplier. These were rated as Sch. 40 for pressure application on underground lines. He had me cut a section of 8" Sch. 40 steel pipe to make the body of the tank from. Anyway, my dad said that this compressor will never be sold to anybody cause it doesn't have the ASME / ASTM tags to go on it, because it was home built basically. I welded in couplings and transferred all connections and safety devices from the old tanks to the one I built. Max air pressure is 125 PSI. I cut the compressor mounts and handle from the old tanks and welded them to the new tank I built.

        Also, as part of our storage system, we are using a 40 gallon Butane Tank from an Oliver tractor. My dad had come up with two tanks from scrapping out two tractors. One of the tanks was bad, big hole in it from being run into by something. Anyway, the tank wall thickness was pretty thick, 3/8". So my dad put 125 PSI of air from our shop compressor on the other tank and soaped all the fitting and joints and let the tank set. It held air and didn't appear to have any leaks around the fittings. That tank is still used to this day for our air storage.

        When I was at Texas Tech studying Mechanical Engineering, my faculty advisor and Thermodynamics professor related a story from Oak Ridge National Labs. After WW2, the lab was using surplus torpedo tanks for air storage. They were compressing air to 4200 PSI. One day, someone asked what would happen if one failed. My professor described the tanks from the torpedoes to be about 24" in diameter and about 20 ft. long. The tanks had been nested in racks about 3 tanks high and 5 tanks across. Well, to answer the question about what would happen if one failed, they took one out to a large open field and purposely caused it to fail with the 4200 PSI air charge on board. The destruction from the blast and flying shrapnel was described as a tiny nuke. After seeing what happened, the storage pressure was reduced to 2400 PSI and the nesting was changed. The tanks were stacked 2 high, and had steel plate between each stack of 2 tanks. Also, the tanks were housed in a hardened blast house in such a way that in case of another failure the shrapnel and carnage would be directed away from people and buildings and out into a "blast zone". That is the story he told us in class one day while we were studying about high pressure steam turbines.

        From personal experience, I have seen what 60 PSI and 200 gallons of water can do on a galvanized pressure tank that the bottom weld gave way on. The tank in question was a 300 standard air pressure tank. About 3-1/2 ft. in diameter and around 7 ft. tall. The bottom of the tank was still on the floor of the well house when we arrived to replace it. There was a big gaping hole in the roof of the metal frame and sheet metal well house. All of the plumbing and control wiring was gone, it flew with the tank and was strewn out from the well house to were the tank landed some 300 ft. away.

        That's all I have to share on this.

        Charlie
        '77 Miller Bluestar 2E on current service truck
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        • #49
          Happened to be watching some "Mega Marvel Something-Or-Other" TV program about building tires and high-end mountain bikes. The statement was made that a 70/70 mountain bike tire, filled to 120psi had enough energy to blow a 200# man to an altitude of 10,000 feet!

          Now, I don't know if that is true or not, but they said it right there on TV, so it must be.
          sigpic
          Capn' Dave
          Plying the canals and rivers of France. Plunder, wenches, good wine...!

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          • #50
            You think that makes sense?

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            • #51
              They get crap wrong all the time. I've been a machinist for a long time and every time there is something machine related I can point out a few mistakes.
              The probably got the decimal in the wrong spot
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              • #52
                Da

                Me no genius, you must be smarter.
                Originally posted by enlpck View Post
                You are most certainly correct: you are not an engineer

                Air, or other compressible fluid (gas) is NOT hydraulic fluid. Compressed gasses store much, much more energy than liquids. The stored energy is available to do a great deal of damage in the case of a failure. Rough rule: 40gal of air compressed to 100PSIG is equivalent to one stick of straight dynamite (if you ar about to respond 'no one here knows what a stick of dynamite is', you are missing the point: even if you have never used it, you wouldn't hold a tin can with a stick in it while it was detonated, nor would you want it in your home.)
                Millermatic 210
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                • #53
                  Originally posted by lanceman73 View Post
                  So, you fill a air tank with 15 psi. Then you fill another tank with thicker walls, it's still the same. I've worked with hydraulics for a long time. 150 PSI is nothing. If that tank explodes, it'll just crack a seem and leek out. There will be no explosions at all. Look at gas cylinders, 2500 PSI, stored on service trucks. There is no problems with that. Still, no propane tanks in my opinion, should be used for compressed air. They are too fat in diameter. I'm not an engineer, but happy with my homemade setup.

                  Thanks,
                  Lance
                  Obviously, YOU have never seen an air tank blow. I have.
                  Air (volume) is compressed. Hydraulic fluid is not.
                  Getting by with something for a long time does not validate that procedure.

                  Griff

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                  • #54
                    How about this . . . .

                    How about this . . . .if you just need volume at a low price, buy a NEW unused propane home supply tank. $300.00 will get you a 30" diameter tank 5 feet long . . . and it is safe to 150 psi . . .

                    Another thought, you build a tank & it carries no certs, it blows, someone is injured, your insurer is going to say . . . . "TOUGH LUCK" buddy . . .
                    Millermatic 251
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                    • #55
                      Lots of opinions about what an insurance company will or wont pay for. One of the main reasons to carry it is in case you do something dumb.

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                      • #56
                        Be Careful Buddy!

                        Originally posted by justinp61 View Post
                        I'm in the process of getting everything together for a air compressor, already have a large Ingersoll Rand pump and have found a source for the motor. I can't find a decent tank near home. I do have some natural gas line pipe that is 30" od, 3/8" wall and a friend has a sheetmetal shop that can cut the ends (3/8") on his plasma cutter. Has anyone ever done this? I'm not worried about the welds, but is there anything else I need to look at?

                        Thanks, Justin
                        is there anything else I need to look at?

                        You may want to look at some Life Insurance.

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                        • #57
                          Why not? The prices I was given for two 30 gallon tanks was $1500.00 each. I've got money, but not that kind of money. I guess that it depends on your needs. My home made tanks are incased in the body and secure from "explosions".
                          Millermatic 210
                          Syncrowave 200
                          Spectrum 625 X-treme
                          Hobart Champion 16 W/
                          Miller 8VS Suitcase
                          Miller 3035 Spool Gun
                          Tons of Tools
                          Microwave
                          Laptop and Printer
                          Speakers in the Back for all to hear Sirius Radio!

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