Science/Engineering/Technical forums

Just a picture of the purple chamber with two 750L/s diff stacks and V170 Turbo on the chamber.
chamber is made from 30" steel pipe with steel ends one removable with big O-ring
after baking for a week at 90 degrees Celsius the vacuum is now down to 2 x 10^-6 torr
the Vacuum will get better with time as the interior steel surface lets go its water and other gunk

I've used one (plain) steel tank. It worked well enough for what I wanted, but took gods own time to get down there every time it had been at STP for a bit. Turns out really clean iron picks up an invisible layer of rust almost instantly (you can actually smell it happening if you're observant - some gets into the air), and this acts like a virtual leak as it decomposes under vacuum. Copper plating it really helped with that one - I did it in situ with some solution, a copper pipe for the anode, and rotated the tank since I didn't have enough plating solution to fill it more than a couple inches deep. Other types of plating might be better, I just happened to have some gallons of alkaline copper plate (the normal, acid kind, won't go directly on steel, you need nickel first, which might have been better anyway, all by itself).

You will need a space suit for the next one Doug.