[Milsurplus] DIY Vacuum Chamber

[Bob kb8tq]

Hi

Indeed, Vacuum in space = empty. You can’t take anything more out of a bucket that has nothing in it. That’s as far as you can go. 

Start with 10 tennis balls in a bucket, take them all out. Ask: "What happens if I take out another ten?”. Answer: You can’t there aren’t any more in there. You just keep reaching into the bucket and coming up empty handed. Nothing happens when you do. 

Pressure can go up and up and up. It can’t go below zero. 

Bob

> On Sep 24, 2026, at 1:37 AM, hwhall--- via Milsurplus <milsurplus at mailman.qth.net> wrote:
> 
> >We can compress gas to tens of thousands of PSI, why not draw as much?<
>  
> Think about it this way: increasing gas pressure comes from increasing the density of gas molecules in a confined space (e.g., cramming more molecules into the same space). You can increase the density that way by a great deal, until molecules become so close together that the gas behaves like a liquid. But going in the opposite direction, once you've removed all the gas molecules from the space, you cannot go any further. There's a limit in that direction; there's nothing less than nothing (except for non-real integers, LOL).
>  
> Of course, pressure can also be increased indefinitely by compressing the same number of molecules into less space. Same effect: more molecules per unit of volume. Similarly, for the same number of molecules, pressure can be decreased by expanding the volume. Fewer molecules per unit of volume. But you can't expand the volume enough to make the density as low as zero molecules would be. So a perfect vacuum won't be reachable by that method.
>  
> >Have one unit of space, pull 300 times that, see what happens<
>  
> No matter how far we draw a piston from a cylinder, the same number of molecules are still in there. There's just fewer per unit of volume. So we'd never be able to reach perfect vacuum inside. And a perfect vacuum inside only causes ~15 psi squeezing inward (on earth).
>  
> Wayne
> WB4OGM
> 
> On Wednesday, September 23, 2026 at 09:00:04 PM MDT, Facility 406 <facility_406 at bruteforcedevelopment.com> wrote:
> 
> > I'm not sure minus 10000 psi has a meaning. Can you make a vacuum that's
> > a harder vacuum than a perfect vacuum?
> 
> Draw harder.  Drawing -15 just means hitting neutral to what we are
> familiar with.
> 
> Have one unit of space, pull 300 times that, see what happens, not
> pulling against the ambient pressure we happen to be within, to relative
> nothing, but what the equipment can actually do, independent of the
> atmosphere.  We can compress gas to tens of thousands of PSI, why not
> draw as much?
> 
> Yes, PSI, is that a thing when it hits zero?  What is PSI when it's less
> than zero.  I'd go with negative, as it's relative, and whether pushing
> a pound, or pulling a pound, it' still a pound, so PSI seems to apply,
> whether it's plus, or minus a pound.
> 
> I really don't know, honestly, but I've had problems, so minus a lot,
> may be a thing.
> 
> Kurt
> 
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