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Homework Help: Helium tank filling parts to a specific pressure?

  1. May 15, 2012 #1
    1. The problem statement, all variables and given/known data
    I have a tank that has 8000 cubic feet of helium in it. I have parts I'm filling to a gage pressure of 0.5 bar. The parts have a volume of 0.05ft^3. How many cubic feet of helium are in each part? Temperature is constant.

    2. Relevant equations
    I'm not sure if I'm missing any important variables...


    3. The attempt at a solution
    I figured it would be 0.05ft^3 * 0.5 bar = 0.025 cubic feet per part, but I'm not sure?

    Any help? (I'm a rookie)
     
  2. jcsd
  3. May 16, 2012 #2

    Astronuc

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    Please note that the parts are being filled "to a gage pressure of 0.5 bar" and recognize the significance of gage pressure as opposed to absolute pressure.

    Also is the He gas in the 8000 ft3 tank at 1 atm pressure? If so, one has to compress the He from an initial pressure to the higher pressure in the part.
     
  4. May 16, 2012 #3
    So do I use absolute pressure instead of gage pressure? So 1.5 bar instead of 0.5 bar?

    The 8000 ft^3 is the amount of He inside the tank at 1 bar not the size of the tank. I'm not sure what the size of the tank is.
     
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