S, knegge pie:
I think you can make falling water get you that kind of vacuum.
You would need a thicker pipe where you spray water downwards, then a funnel shape at the bottom of that and connect it to a hose. A bit like a oil diffusion pump, just vertical.
The hose need to have at least 11m drop so it can pull some air with it on its way down. It also got to be just the right thickness to trap the air and also allow for a decent flow.
The drop could be a hill, it's the vertical distance that counts.
I can think of all kinds of problems with this design, but it's simple enough that you can power it all by hand. Making it more reliable will need a lot of tinkering. Also, it needs icy cold water (:
This seems like ejector for me. And presure reached can't be under water vapour presure. So as you write the vater should be ici. I was tryed (far ago) the ejector pump in water tap pipe and as I remember I got 50 mBar presure with 5 Bar water at aprox 15 Centigrade. Not bad but stil to high.
I tryed design from
ie just PVC pipe attached to gauge and rollers and can get under 1 mBar. Just not sure how long I need to 'roll' to evacuate 5 liter box. Maybe some kind of peristaltic pump?
And how to measure vacuum? Some idea? (Ocassionaly I can borrow digital instrument but just for few hours or a day max) I thinking on to build pirani gauge, but afraid that this type of instrument is for lower presures. The another idea is to just make small chamber with little watter and thermometer. As watter evaporate (under vacum) it will coll down. And with reading temperature we can calculate the pressure?!? Does somebody try that already?
Slavko
