I am thinking of playing around with food in partial vacuum conditions (ie water boiling at room temperature). But, as it is more a curiosity, I'd rather not spend too much money right now. That inspired me to be a little creative with stuff I already have.

I have a pressure canner (heavy duty aluminum), an AC vacuum and sheets of 3/16" acrylic. The acrylic would be nice to use as I can keep an eye on what is happening.

I don't think the acrylic is thick enough to withstand the pressure, so I was thinking of ways to combine them somehow.

Here is a proposed solution. For the first sheet on the low pressure side, drill some holes in the sheet to reduce the pressure, but make the holes small enough that it is not able to come to an equilibrium while the pump is in operation. Then another sheet is placed on top of it with a gasket to keep them separate. This next sheet would have smaller/fewer holes in order to .. In theory, this could continue indefinitely, then an unperforated sheet at the top.

Here is an illustration (note, I missed gaskets around the vacuum outlet):vacuum semiperforated seal

  • a=pressure canner
  • b=sheets of acrylic
  • c=gaskets
  • d=vacuum outlet
  • e=larger holes
  • f=smaller holes

I am not particularly sure I want to do this, but I am curious if the general concept is sound.

One possibility is that it could work, but the holes would be smaller than I could reasonably do in my home shop. Acrylic isn't great for drilling.

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    $\begingroup$ It looks like you can get a small bell jar setup for ~$110. Are you sure the time cost of a project like this is worth it? $\endgroup$ – Chris Mueller Feb 22 '16 at 16:37
  • $\begingroup$ @ChrisMueller At this point, I am mostly curious if the general concept is sound. I could see myself getting a 2nd hand bell jar if I could buy and sell it fairly easily.. Craigslist doesn't seem to have many in my area, though. $\endgroup$ – sthgrau Feb 22 '16 at 17:19

No, this idea won't work. Except for the start-up transient, there will be no flow of air through all of those holes, and the top (unperforated) plate will still be experiencing the full force of the pressure difference between outside and inside.

Better to just stack up N sheets with no holes and no space between them.

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