Vacuum Sealant

[Aidan Cookson]

Would using vacuum sealant be a viable alternative to welding the flanges and half nipples onto the hemispheres? Also, is it a good idea to have an angled tube between the turbo pump/vacuum gauge and the chamber to reduce contamination? Thanks

[Richard Hull]

Vacuum sealant is not to be used on a metal chamber. Sealant is not a glue. I assume you mean a vacuum rated epoxy. There is no substitute for welding or silver soldering the various flanges and such on a fusor. TIG welding is the preferred method used on standard 304 stainless steel.

It is always wise to put a right angle turn on any gauge port to avoid direct beaming and limit deposition. Most often a turbo pump is equipped with a wire screen to avoid any larger material items form enerting it during operation. A right angle turn would be better with the screen, but will hurt conductance and with a large throat, cost a good deal for the fitting.

Richard Hull

[Aidan Cookson]

Vacuum sealant is not to be used on a metal chamber. Sealant is not a glue. I assume you mean a vacuum rated epoxy. There is no substitute for welding or silver soldering the various flanges and such on a fusor. TIG welding is the preferred method used on standard 304 stainless steel.

It is always wise to put a right angle turn on any gauge port to avoid direct beaming and limit deposition. Most often a turbo pump is equipped with a wire screen to avoid any larger material items form enerting it during operation. A right angle turn would be better with the screen, but will hurt conductance and with a large throat, cost a good deal for the fitting.

Richard Hull

Ok, so you think I should have a right angle turn on the gauge port, but not on the turbo pump? The gauge is a pirani/inverted magnetron combined gauge and the turbo pump is a varian microtorr V70D which does have a screen. Thanks

[Richard Hull]

Thanks for re-quoting what was just above your re-quote...I had totally forgotten what I had said and needed to read it again. Others will have the thrill of re-reading my thoughts for a second time just seconds after reading it the first time.

If you have the money and time put a bend on both for sure. You do not have to do either. Probably nothing will happen with straight connections, if you wish to chance it. Do you feel lucky?

Richard Hull

[Richard Hull]

Thanks for re-quoting what was just above your re-quote...I had totally forgotten what I had said and needed to read it again. Others will have the thrill of re-reading my thoughts for a second time just seconds after reading it the first time.

Richard Hull

Kinda' stupid ain't it?

Please everyone...........Do not use quotes at all unless it is logical and genuinely needed.........Like when you are quoting a small fragment from another thread or from a current thread that is 25 postings above your current reply. Try to avoid requoting a 15 paragraph post. Quote only what fragment you intend to comment on and never quote from a posting immediately prior to your reply. The flow is already there! Logic and reasoned common sense please.

R.H

[Aidan Cookson]

Ok, sorry, I don't post on forums of any kind much. And I'll just get an angle, I don't feel like taking that chance with the gauge.

[Richard Hull]

Yes, always try and protect your gauge. This is very important with the ultra expensive and sensitve capacitive manometer types (Baratrons). Direct beaming into one of these is not nice.

Direct beaming into a running turbo pump is of little concern. You are just hiting one of many rotating blade sets and the screen will hopefully obviate a lot of that stream.

Richard Hull