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Anyone know how much vacuum a mason jar can handle?

Discussion in 'Preparedness & Survival' started by Mark W., Feb 27, 2012.

  1. Mark W.

    Mark W. Silverton, OR Bronze Supporter Bronze Supporter

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    I have a Medical grade vacuum pump that will draw vacuum down to very near zero psi. I have used this vacuum pump to bust 1.5" x 1.5" Oak board by drawing down the vacuum and allowing the 14+PSI atmospheric pressure to push on the boards stacked acorss each other.

    This experiance leads me to wonder how far down I can draw a large mouth mason jar before it breaks.

    Looking to do some food storage.
     
  2. knuckle Head

    knuckle Head southeast Well-Known Member

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  3. chemist

    chemist Beaverton OR Well-Known Member

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    At sea level, the maximum vacuum that can be applied is around 15psi, and that's well within the range that a Mason jar will tolerate. That 15psi of differential pressure represents full atmospheric pressure against full vacuum.

    It's not possible to generate more vacuum, because the force is due to the atmosphere pushing down, and there's only 15psi of air on top of us (equivalent to 760mm height of mercury, if you prefer).
     
  4. Unka-Boo

    Unka-Boo Milwaukie Active Member

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    ....and where did you come up with this?
     
  5. jake2far

    jake2far Portland Bronze Supporter Bronze Supporter

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    The measurement scale would be in inches of mercury, Pascal, Torr, MilliTorr.
    In MilliTorr the mason jar would be able to sustain below .1 MilliTorr. It can handle as far down as you can pull it.
    Vacuum Basics

    Jim
     
  6. Mark W.

    Mark W. Silverton, OR Bronze Supporter Bronze Supporter

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    OK thats basically what I needed to know.
     
  7. Jamie6.5

    Jamie6.5 Western OR Well-Known Member

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    It's a fact Unk.

    There is no such thing as suck.
    There is only positive pressure pushing from the other side.
    Atmospheric pressure is 14.7 PSI

    The force=high pressure>low pressure.
     
  8. Unka-Boo

    Unka-Boo Milwaukie Active Member

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    Ahhh....gotcha...sorry...been twenty years since my last physics class. I had "inches of

    Vacuum" on the brain, not pressure differential.
     
  9. chemist

    chemist Beaverton OR Well-Known Member

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    Atmospheric pressure near seal level is equal to thirty feet of water, or thirty inches of mercury.
    What people usually don't 'get' is that even a rough vacuum is almost the full 14.7 psi, and that getting to a perfect hard vacuum applies almost no additional force on the container.
     
  10. jake2far

    jake2far Portland Bronze Supporter Bronze Supporter

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    After all this I believe the question relates to food storage.
    The best answer to safe food storage is low oxygen content. Using vacuum alone the MilliTorr level should be below .500
    The very best storage is achieved when using artifical atmosphere, no matter what vacuum you pull the oxygen % is always 20%, if you pull a vacuum and flush with CO2 the oxygen content can be lowered below 1/2 a percent, this lower O2 content combined with CO2 preserves the food. Vacuum alone is not the best answer.
    Here is one source:
    CO2 Technologies - About Us

    Jim
     
  11. chemist

    chemist Beaverton OR Well-Known Member

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    Agree that vac alone is not the best answer, but applying rough vacuum along with oxygen and/or water absorbers is by far the best way to go. It's just inconvenient, since glass jars are heavy, fragile, and generally not as space-efficient as multilayered Mylar bags.