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Subject: 
Re: Home-made One-way valve
Newsgroups: 
lugnet.robotics
Date: 
Thu, 20 Dec 2001 14:11:59 GMT
Original-From: 
Andy Gombos <gombos_2000@yahoo.&AntiSpam&com>
Viewed: 
3049 times
  
> Lowering the air pressure in the Lego tank allows the system to do work
> by having the higher pressure outside the tank refill it.  There is no
> "vacuum" anywhere in the system.
> 
> > > So I checked with the local supplier of industrial gases. If you need • a
> > > tank of compressed air, that's no problem. But a tankful of vacuum, er
> > > that's not listed in the catalogue.
> 
> I'm sure they have a price for "Empty Tanks" in that catalog.  If they
> delivered the empty tank with air at one atmosphere in it, that would be
> just a bonus!  You'd have a tank full of vacuum *AND* some free air.
> 
>    :-)
> 
> > But then, they are a supplier of gases rather than a supplier of empty • tanks
> > ;)
> > Besides, almost everyone owns a vacuum cleaner, and so can create their • own
> > vacuum easilly enough.
> 
> A vacuum cleaner is poorly named.  If it actually did create a vacuum,
> it would have to be bunged up because it relies on the outside air rushing
> into it's lower pressure chamber to push the dust and dirt inside.
> 
> Creating an actual vacuum (a total lack of particles) is essentially
> impossible - even deep interstellar space has hydrogen gas at densities
> of millions of atoms per cubic meter.

So, define vacuum as an area of lower pressure than the surrounding
environment.  I think that satisfies most if not all of your requirements,
and is what most people seem to think of when they mention vacuum.

Andy



Message has 1 Reply:
  Re: Home-made One-way valve
 
(...) So you are happy to say that you can increase the amount of vacuum in a sealed tank by placing it at the bottom of a bucket of water? Mmm'K. ---...--- Steve Baker ---...--- Mail : <sjbaker1@airmail.net> WorkMail: <sjbaker@link.com> URLs : (8 (...) (25 years ago, 20-Dec-01, to lugnet.robotics)

Message is in Reply To:
  Re: Home-made One-way valve
 
(...) Argh! <rant> It's been a long time since domestic lightbulbs were even partially evacuated - these days they are filled with some kind of relatively inert gas. Back in the 1940's and 50's they were partially evacuated - and on some old movies (...) (25 years ago, 20-Dec-01, to lugnet.robotics)

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