Ok that is interesting.? I got lost in the back and forth.? Them peoples dont seem very friendly.? Did the pump work ??? ?

I have not posted much about my vacuum system ( 68" dia x 68" long chamber with twin 8" diff pumps ) because it was just working great for the last year or two.? I even put in a 500 gallon recirculation water supply for the diff pumps that is saving something on the planet.

Well you just knew it was too good to last.? I pumped down Sunday to start a coating operation on a spun cast epoxy mirror ( for a Dr bud in SC ) and come Monday when it was time to get serious and really pump down the system tore itself apart.? The inter-cooler sprang a leak while under high ( hot ) vacuum. ?

I had to make a field repair to an old CVC 8" throat inter-cooler years ago and my armature TIG welding choose this week to fail.? I will spare the gory details ..... suffice to say a gallon of coolant water dumped into an 8" dia diff pump in high hot vacuum was a pretty spectacular site.? By the time I could get it all locked down the leak had filled the chamber up with fog ?and slogged my Welch pumps.? Yes the fun instantly fouled both the diff pumps and both the Welch pumps and the hot cathode sensor and the telescope mirror and all 36 tungsten emitters in the chamber. ?

It has been so much fun wiping and cleaning my chamber.? I just cant remember the last time I spent that much quality time tearing the sytem all apart.? But I found the problem and now just have to TIG it back to pressure tight. ??

It seems DOW 704 oil really dont explode when you have a catastrophic failure.? It makes a mess but nothing actually got hurt.? I suppose it was worth the $500 it cost after all.? Sad they don't sell it anymore. ?

Anybody got a recommendation on replacement diff pump oil ???? I see Leskers has a version 702 and 704.? Anybody used it ???

Drew in sunny Florida?

On Tue, Oct 14, 2014 at 3:16 PM, geoani@... [VacuumX] <VacuumX@...> wrote:

?

Being a hardcore experimentalist I thought I'd test to see if this forum can still fog a mirror. (That's a metaphorical double entendre, I suppose.) Anyhow, a few months ago I designed and built a new kind of diffusion pump and thought I'd test the waters here with this link:

The whole idea went downhill very quickly over there as far as responses go. It's hard to find much of an audience when your discussing ways to obtain higher levels of deep nothingness. My wife has suggested that I start looking into prices for a lobotomy. She thinks I'd be better company after the procedure.