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Re: NEON- Another cold cathode question



Lisa asks:

>Has anyone been able to repeatably pump 2 8-foot 20 mm tubes, at once, with
>either the Eurocom 'Turbo' system, or the Voltarc Neovax?

Lisa:

There are others who can give a more diffinitive answer, however, I believe 
either of these "high end" systems should be adequate.  The most demanding 
portion of the evacuation is in the high vaccuum range.  At this point, air flow 
becomes laminar - which means that each molecule is more likely to collide with 
a surface than with another air molecule.  Collission with the wall surfaces 
resist evacuation (kind of like friction).  With the larger diameter tubing 
(20mm) the air molecules can travel farther without hitting a glass wall so 
there is less resistence to evacuation. Think of the effect of going from 5mil 
tubulation glass to 6mil tubulation - much better evacuation of your tube.

Final determination of an operating spec must always be the product 
manufacturer.  Ask Voltarc and Eurocom and if you purchase the unit, make sure 
this specific application is clearly stated within the operational performance 
criteria for the pump station.  The units you cite may be capable, but they may 
not be the most effective.  By clearly stating your requirements to Voltarc or 
Eurocom, they will beter be able to provide the correct equipment to accomplish 
your tasks.

Hope this helps,

Tim
cent@interserv.com


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