Abusing compressor as a vacuum pump

oops. The sketch is vacuum_venturi_sketch2.jpg

Thanks again, Don!

Yes, please do. I'd like to see how yours turns out. I'd also like to hear how you bored that tapered hole for the air exhaust.

Finished: I finished it today and tested it. It pulls (I don't have a longer tube that fits!) 2m of water without problems. That is 0,15m Hg. Will buy a longer tube tomorrow and climb the ladder.

As soon as I know the upper limit (or are out of ladders), I will draw a plan and publish it. To make you curious: It looks cute, I made some mods! :-)

Thanks again Don, thanks group!

Nick

See my other posting. It is finished, but I have just 2m of tube to test it. It's pulling these 2m of water easily (and makes a wounderful mist), with 2 bar (30 psi) on the input side.

The tapered holes: Well, you need to make two conical D-bits out of drill rod. Not to complicated if you have a lathe. I also made some changes. Basicaly, it is out of hex stock (aluminium) that did the job and looks good. On the air inlet side, I modified a quick release fitting for compressed air (don't know how this is called) so that it also forms the jet. And on the vacuum side, I pressed in some brass tube.

Wait 'till tomorrow. I'll keep you informed (have to buy longer tube) with pics and plans.

Nick

ok, for what it's worth, I sell vacuum pumps mostly to wood workers to make vacuum chucks from - this is a similar application to what started this thread. - to help people decide what kind of pump to get, I created a reasonably definitive paper on the subject - you can find a link to it in the vacuum pump secion of my web page

maybe that article will be helpful - I'd discourage a venturi.

bill