-- MarkWard - 16 Jan 2017

Performed a pumpdown and vacuum hold test to ensure equipment is operating as expected.

Attempt to determine when the Pressure gauge (Omega manometer type) 209x becomes none linear due to reaching its zero point.

This appears to occur at approximately 1.6psia or 80torr


Hornet gauge remains good till flattening off due to significant pumping speed reduction below approx 3torr (4mbar) for the scrollvac5


High pressure behavour looks consistant, theoretical pumpdown of an 80 l chamber from the above pumping curve predicts roughly the same pumpdown curve.

Hornet Gauge and Omega gauge when converted to same units look well matched.

Performed two rate of rise measurements, both appear to be linear with a very slow curve developing. This usually indicates a leak, though cannot rule out outgassing, the elastomer seal on the vessel always smells which means it is outgassing significantly.

Points to check/reseal to be sure are - NPT fitting on the manometer type gauge. Leak rate (if it is a leak) comes out at roughly 10^-3 mbarl/s which is fairly high... even for outgassing.

Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng GaugeLinearity.png r1 manage 54.4 K 16 Jan 2017 - 13:42 MarkWard FirstPumpdown Test with notes
PNGpng LeaksvsOutgassing.png r1 manage 29.0 K 17 Jan 2017 - 16:26 MarkWard  
PNGpng ScrollVac.png r1 manage 55.2 K 16 Jan 2017 - 14:15 MarkWard  
Edit | Attach | Watch | Print version | History: r2 < r1 | Backlinks | Raw View | Raw edit | More topic actions

Physics WebpagesRHUL WebpagesCampus Connect • Royal Holloway, University of London, Egham, Surrey TW20 0EX; Tel/Fax +44 (0)1784 434455/437520

Topic revision: r2 - 17 Jan 2017 - MarkWard

This site is powered by the TWiki collaboration platform Powered by PerlCopyright © 2008-2021 by the contributing authors. All material on this collaboration platform is the property of the contributing authors.
Ideas, requests, problems regarding RHUL Physics Department TWiki? Send feedback