Stanford Research Systems RGA100, Operating Manual And Programming Reference

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Installation 1-7
SRS Residual Gas Analyzer
and do not use non-metal gaskets.
Important : Avoid touching the internal walls of the vacuum port with the repeller
cage during the installation procedure, since that could lead to serious misalignment
of the ionizer. Get an extra hand from a co-worker if necessary.
Probe Assembly
RGA Mounting Flange
Ionizer
Vacuum Chamber
Vacuum Port
RGA Cover Nipple
Figure 1 RGA Probe Installation
5. Insert the 6 bolts through the holes in the flanges and fingertighten them. Tighten the
bolts according to the standard tightening procedure for 2 3/4”” CF flanges. Use 1/8
turns in crisscross order: 1, 4, 2, 5, 3, 6, 4, 1, 5 , 2, 6, 3, 1.... until the flanges are in
contact, and finish the tightening process with an extra 1/16 of a turn on each bolt.
6. Start pumping down the vacuum chamber as soon as the flange connection is sealed.
The RGA probe is pre-cleaned and leak tested at the factory and should only
contribute to the base pressure of the vacuum system through regular outgassing (i.e.
mostly water) from its walls. If available, use the vacuum system’’s total pressure
gauge to leak test the probe’’s connection and monitor the chamber’’s pressure as a
function of time.
Important:
x
Redo the metal seal if a leak in the vacuum system is detected after the probe is
installed. Inspect the integrity of the seals before positioning the new copper gasket .
x
Contact SRS immediately if a leak in the feedthru flange is detected or even
suspected.
x
Consult the Probe Bakeout instructions of the RGA Maintenance chapter if a bakeout
is needed prior to exposing the probe to the vacuum system’’s main chamber.
x
An overnight pump-down is needed in instruments with the electron multiplier option
(Option 01). Consult the CDEM Preconditioning section of the RGA Maintenance
chapter before applying any voltage across the CDEM.
x
If available, use an ohmmeter to check for shorts between the feedthru flange
connectors and the walls of the vacuum chamber. Vacuum ports with severely
misaligned CF Flanges and/or large internal weld joints are not uncommon, and can
result in a short between the ionizer and the inside walls of the vacuum port tube. If a
short is detected, use the Feedthru Flange Connectors drawing in the RGA Assembly