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Convert pressure & energy /TnT equivalent to vol.

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  • Convert pressure & energy /TnT equivalent to vol.

    Hello all, after all my searching I just might have found some of the brightest minds that can help me.

    I was giving a sheet to bid on a project to pressure test a system with air . I asked a simple question when they called me to quote the job. I asked the test pressure and volume, this was so I could understand the volume and how many 1650 scfm compressors I will need to bring out to pressure the system up in a timely fashion.

    Here is what I have:

    Design pressure is 275 psig, Test pressure is 303 psig, Energy ( Ft-lbs 87,646,838) , TnT equivalent 59 lbs,

    Is there a way to calculate the volume of the vessel based off of the Pressure and the energy stored ? There is no reference to temperature that I assume will plat a factor in this as well. I am not in any way trying to portray myself as smart as some of you when it comes to this. but am requesting help if you can provide any.

    Thank you

  • #2
    TNT as in Trinitrotoluene? How da heck do you test with that, just toss a couple sticks in the vent? FIRE IN THE HOLE!!!
    As for your question, I think if you convert PSIg to PSFg, and divide your energy by that you'll get a result in cubic feet. In this case I calculated about 2008.77 cubic feet. I donno if that's accurate, but I couldn't think of a better way.
    Personally, I'd do it the TNT way but maybe that's why I'm not working.

    Comment


    • #3
      Originally posted by gubment_cheez View Post
      TNT as in Trinitrotoluene? How da heck do you test with that, just toss a couple sticks in the vent? FIRE IN THE HOLE!!!
      As for your question, I think if you convert PSIg to PSFg, and divide your energy by that you'll get a result in cubic feet. In this case I calculated about 2008.77 cubic feet. I donno if that's accurate, but I couldn't think of a better way.
      Personally, I'd do it the TNT way but maybe that's why I'm not working.
      thank you, I will try it out .

      Comment


      • #4
        Originally posted by gubment_cheez View Post
        TNT as in Trinitrotoluene? How da heck do you test with that, just toss a couple sticks in the vent? FIRE IN THE HOLE!!!
        As for your question, I think if you convert PSIg to PSFg, and divide your energy by that you'll get a result in cubic feet. In this case I calculated about 2008.77 cubic feet. I donno if that's accurate, but I couldn't think of a better way.
        Personally, I'd do it the TNT way but maybe that's why I'm not working.

        TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The ton of TNT is a unit of energy defined by that convention to be 4.184 gigajoules,[1] which is the approximate energy released in the detonation of a metric ton (1,000 kilograms) of TNT. In other words, for each gram of TNT exploded, 4184 joules (or one large Calorie = 1,000 calories) of energy is released.

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        • #5
          I'm familiar with the term. I found it amusing that it would be used within the context of an air pressure test, since in my experience it's used in a pretty limited scope, and tens of pounds of TNT is so small relative to the scope I was offline-questioning the sanity of the entity that had requested your quote.

          Comment


          • #6
            Originally posted by industrial commissioning View Post

            thank you, I will try it out .
            Remember that the gas equations use absolute, not gauge, pressure, but I agree the volume appears to be about 2000 cubic feet. Remember this is the container volume, and it will take about 21X this volume of "free air" to fill it. Compressors are normally rated by the volume of free air (at atmospheric pressure) they move at a stated output pressure. I find it very odd that they would only tell you energy and not state the volume of the tank.

            Comment


            • #7
              Originally posted by JohnS View Post

              Remember that the gas equations use absolute, not gauge, pressure, but I agree the volume appears to be about 2000 cubic feet. Remember this is the container volume, and it will take about 21X this volume of "free air" to fill it. Compressors are normally rated by the volume of free air (at atmospheric pressure) they move at a stated output pressure. I find it very odd that they would only tell you energy and not state the volume of the tank.
              We are a relatively small company in prospective to most , we are still having to prove ourselves as a contender in a cutthroat industry to some of the veterans . I have been in this industry for 25 years and my partners for even longer. All of our experience means nothing it seems because our company is considered new and inexperienced even after 6 years. So they are trying to test me to see if we can even understand what they sent or its a simple oversite on their side. Ether way I will not ask for volumes . I sent this over to my engineering manager and he made short work of it. I spent some time last night and this morning going about it different ways and came up with almost the same answer as him . I used gauge and he used absolute. with that being said I used absolute and we now are in line with each other or should I say I am now inline with him . Thank you for your help. I am still fascinated and get enjoyment finding and coming up with answers to problems. Bet this is very simple to most of you but does take me a little longer to understand some of it but I will keep at it until I learn. my whole career even with the answer I will ask the methods so I can learn from it.

              Comment


              • #8
                Originally posted by gubment_cheez View Post
                I'm familiar with the term. I found it amusing that it would be used within the context of an air pressure test, since in my experience it's used in a pretty limited scope, and tens of pounds of TNT is so small relative to the scope I was offline-questioning the sanity of the entity that had requested your quote.

                Think they were using it was a secondary measurement of stored energy.

                Comment

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