Re: vacuum pump

Tesla List wrote:
> Original Poster: "Harri Suomalainen" <harri.suomalainen-at-pp.inet.fi>
> >When this thread started, I tried my water bed aspirator with a vacuum
> >I only got to 15 inches of vacuum and it had a nasty habit of injecting
> >down the vacuum line.  Maybe mine was bad, but one should be cautious about
> >these cheap devices.  they are definitly far short of the fancy lab grade
> >devices...
> Vacuum sucking devices (the ones you connect to water supply, so called "Jet
> Injectors") indeed have a nasty habit of letting some water to the vacuum
> This
> happens whenever preassure drops quickly at vacuum side. Unfortunately this
> happens
> also when you decrease the amount of water running (not enough sucking
> Water should be turned off *very* slowly in order not to get water to the
> vacuum
> line.
> Beware of the preassure changes in the water supply. If water preassure
> suddenly
> decreases (less water running) system will suck some water immediately.
> The usual precaution for this problem is to use a so called Wolf's bottle. It
> is a device
> where one line comes in and one goes out. If some water is drawn into the
> bottle
> it will drop to the bottom. Vacuum line is connected to another connection
> which
> will still be way above the surface of water. Therefore no water goes to the
> vacuum
> line. This simple device will therefore protect the vacuum system.
> Absolute preassures in the range of 10mmHg or so are common to this kind of
> vacuum pumps. It will never go below the vapor preassure of water at the
> temperature
> water is in. Below this is never possible.
> Harri Suomalainen


        Thanks for the note; looks as if you have experience with the devices. 
Do you by any chance have any design information?