[Milsurplus] DIY Vacuum Chamber

[Facility 406]

On 9/22/2026 00:14, Jim Whartenby via Milsurplus wrote:
> When a pressure cooker is cooking, it has about 15psi on the inside 
> pushing out.  When used as a vacuum chamber, the 15psi is on the outside 
> pushing in.  Evidently, the aluminum container can't tell the 
> difference!  <grin>

I suppose so, after looking at several charts.

Pressure?  Let's hope the regulator is working.

Vacuum?  Looking at my old pump, it seems to be rated to around 0.009 
"PSI", not quite 0, or about -15, so, yeah, in or out on the pressure 
cooker.

I was confused by a system I was paying with that was pulling about -225 
pounds, but I'd have to run some numbers on the surface area, seems to 
me it was only a few square inches.  If the roughly 5 I'm thinking, 
that's -45 pounds per inch, triple of -15, or one atmosphere.  Which 
leads to the question:

If a 1 ton weight is pulling on a 1 inch rod in a cylinder, assuming the 
seals hold, what is the "pressure" of -2,000# PSI?  I get confused 
looking at the charts in the minus 14 million Pa range, but I'm guessing 
it'd suck in a  few mm thick of cast aluminum, unless there's a lot more 
I have no clue about, like, sure, the atmosphere can only push so much, 
but how much can 2,000 pounds suck?

Kurt