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c s soh <cssoh@singnet.com.sg> wrote in message
news:3C213F4F.CC899E8@singnet.com.sg...
> Jared wrote:
> >
> > Alternativeley you can continue using the valve with the old style pump • and
> > have an air tank (if you own two) on each side i.e. one that holds the
> > vaccum and one that holds the pressureized air.
>
> Somehow I'm a bit queasy about this business of "storing vacuum" in a
> tank.
How about a vacuum flask (thermos), domestic lightbulb, or even CRT (cathode
ray tube such) as in your TV or monitor. These all rely on a stored vacuum.
> 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.
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.
> It seems the only way to maintain vacuum is to have a motor-driven
> exhauster working all the time. That's how its done in the vacuum brake
> system on trains.
> --
> C S Soh
>
> CSSoh's Lego Pneumatics
> http://www.geocities.com/cssoh1
> ... where air is power!
The problem with using air tanks with the old pneumatics lies in the switch.
When you flick the switch to allow compressed air into the cylinder, the
vacuum side is connected to the exhaust and vice versa. The only use I could
find is to build up pressure/vacuum in a pair of airtanks when the switch is
central so that when the switch is moved, the cylinder moves with a bit of a
kick. You then have to centralise the switch again, and build up the
pressure/vacuum again to move the cylinder back with a kick.
To summarise, when you have an airtank in each line between the diode and
switch, and you are using the pressure from one tank, the other is
automatically exhausted ;(
(Duckie) Dave Till
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Message has 1 Reply:
 | | Re: Home-made One-way valve
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| (...) 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 (...) (23 years ago, 20-Dec-01, to lugnet.robotics)
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Message is in Reply To:
| | Re: Home-made One-way valve
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| (...) Somehow I'm a bit queasy about this business of "storing vacuum" in a tank. 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 (...) (23 years ago, 20-Dec-01, to lugnet.robotics, lugnet.technic, lugnet.build)
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