# Anyone know how much vacuum a mason jar can handle?

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

1. ### Mark W. Silverton, OR Bronze SupporterBronze 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.

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3. ### 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 Milwaukie Well-Known Member

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

5. ### jake2far Portland Active Member

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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. Silverton, OR Bronze SupporterBronze Supporter

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OK thats basically what I needed to know.

7. ### Jamie6.5 Western OR Bronze SupporterBronze Supporter

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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 Milwaukie Well-Known 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 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 Portland Active Member

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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

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