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Discussion Starter · #1 ·
I would like to build a vacuum chamber that I can use for science experiments with the grandkids. I checked several DIY websites, but a lot of them actually looked dangerous.

Are there any plans for a safe vacuum chambers that don't cost a fortune? I'm happy to spend at least $100. And that don't require sophisticated tools or equipment?

I'm thinking about a round glass container about 18-24" tall and maybe 12" in diameter. I;d like it to have a lid that I can modify to allow things like dropping a feather in a vacuum to demonstrate Galileo dropping things off the Leaning Tower of Pisa.

Thanks for any leads or tips.
 

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Discussion Starter · #2 ·
PS: I'd prefer something I (we) can build, but of that's unrealistic, I'm willing to buy something ready made.
 

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when other people are in close proximity, especially kids, I would be so leary of a glass or plastic container imploding and sending shards all over the room.
there are domes especially made for vacuum tables: you would have to google a source for it.
for woodworking projects, we use a metal paint pressure pot, but that would defeat your purpose.
do the ole YouTube search and see what you can find.
 

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Discussion Starter · #4 ·
I hear you. I did check YouTube. That's why I said that a lot of those videos looked dangerous. I plan to buy a very sturdy glass or plexiglass jar. And I don't plan to achieve a perfect vacuum. It ought to be possible.
 

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I have a hand vacuum pump for auto repairs. I recently bought car AC gauge and some of them were packaged with electric vacuum pump. Neither is cheap. Not sure if you want to spend maybe $200 for the pump and some sheets of 1/4 plexiglass just to visualize things? Vacuum just means absence of air (molecules) so no resistance, and not sure if young kids can equate the two. You'll also have to make a cap and somehow ways to detach things like feather from that cap, all without losing the vacuum.
I tested the hand vacuum pump using my finger to block the opening, so at the zero degree vacuum, would there be an implosion? That is something else to think about.
 

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I guess you could submerge your candidate container in water so that the surface sees twice atmospheric pressure, 30 PSI, as a test.

For safety, you could enclose it with a few layers of clear plastic.

How about a clear tube 4" in diameter?

How are you going to pump it out?
 

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Discussion Starter · #7 ·
How about a clear tube 4" in diameter?

How are you going to pump it out?
I found some 3" clear Acrylic tubes on Amazon. It doesn't say how strong they are.

I thiught I'd look for some kind of vacuum pump. It doesn't have to get every last molecule of air. A 50% vacuum would probably be good enough.
 

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I found some 3" clear Acrylic tubes on Amazon. It doesn't say how strong they are.

I thiught I'd look for some kind of vacuum pump. It doesn't have to get every last molecule of air. A 50% vacuum would probably be good enough.
You might get that with a vacuum cleaner within seconds, but soon the motor's thermal overload would kick out.
Expect the housing to be seriously temporarily dented.
With that & the noise the kids' eyes will get pretty big. :D

You might be able to rent a proper setup from a lab supply outfit & get a pretty hard vacuum.
 

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You might also look up exploding wires.

You can do this with any wall plug & a single strand from a lamp cord.
It will leave smudge marks on the receptacle & make an unearthly sound.
Wear goggles or put a plexiglas sheet between it & personnel.
More than a single strand may pop a breaker.

Big eyes for sure & it may turn them away from a career in the elec. power industry. :D
 

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It is unpredictalble when or if a container not designed for evacuation will implode and at what amount of negative pressure.

Here is one experiment you can do safely.

Get a large glass bottle with a neck big enough you can insert a balloon inflated with just enough air to get the wrinkles out, and small enough to attach a vacuum cleaner house using duct tape.

Put the balloon (with neck tied off) inside and turn on the vacuum'. You will (should) see the balloon expand.

(Do not keep it turned on for a long time and do not use a lab or industrial vacuum pump since this will make an implosion hazard.)

The balloon expands because the air pressure outside it was reduced while the air inside does not have its pressure similarly reduced. (The pressure inside the ballon does not remain absolutely constant because the rubber balloon exerts some compressive force depending on how much it is stretched.)

Vocabulary: PSIG -- gauge pounds per square inch. Air pressure as measured by a typical gauge. Atmospheric pressure on the ground is roughly 15 PSI absolute while typical gauges read zero which is accurate enough for measuring boiler pressure, expansion tank pressure, tire pressure, etc.

You can do this with any wall plug & a single strand from a lamp cord.
It will leave smudge marks on the receptacle & make an unearthly sound.
When a medium tension line fuse (e.g. pole transformer fuse) or a high tension line fuse blows due to a short circuit then you get the unearthly sound times a thousand, namely a loud pop or bang that can be heard several city blocks or football fields away..
 
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When a medium tension line fuse (e.g. pole transformer fuse) or a high tension line fuse blows due to a short circuit
Not from a single strand of wire from a lamp cord. 250A is the most this strand is likely to see.

I imagine the PoCo grid withstands a lot more insulting things several times/day.

BTW, a bunch of kids once threw a fine chain into a substation hoping to watch it vaporize.
It didn't. It brought down the whole neighborhood.
I guess they then beat feet out of there. :)

Nowadays somebody would do that just to post it online. :(
 

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You can purchase bell jars and other vacuum containers--or the entire set-up--from Carolina Biological. If you buy just the container, you're still left with `needing a base that is air tight as well as a way to connect your vacuum pump. But maybe looking at what they offer will give you some ideas.
 

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A bell jar with a stand and a vacuum pump and your good to go. Bell jar needs a valve.
Unless you spend a ton on a vacuum pump all you will get is about 50 microns. I have a two stage pump that gets a bit below 50. 50 is nothing to worry about collapsing the bell jar.
It is an very expensive machine that gets below this level and they run for weeks. We are not talking outer space.
 
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