SRS Labs QMS 100 Series, User Manual

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Introduction 1–3
SRS QMS Gas Analyzer
needs of most users. For users with specialized needs, the QMS can be controlled from user programs.
The Technical Reference Manual discusses details of the QMS, its programming, and service.
External Connections
The instrument has two gas connections: an inlet on
the front panel and an exhaust on the back panel.
The inlet connection is a 1/4 inch Ultra-Torr port,
which is a high vacuum o-ring seal. The capillary is
installed in this port. The port is sealed and released
by turning the knurled nut. To release a capillary,
loosen the nut 1/2 turn. When installing a capillary,
press the end fitting on the capillary completely into
the port. Turn the nut finger tight to make the seal.
The o-ring seal relies on clean smooth surfaces and
precision machining to achieve the vacuum seal.
Excessive force or grease are not required nor
helpful. Keep the fittings free from dirt and dust and
the port will maintain a quality seal. The o-ring can be
inspected for damage by completely removing the nut
and ferrule.
The standard capillary shipped with each instrument
consists of a 0.005 inch bore PEEK capillary
designed to work at atmospheric pressure. The end
fitting which attaches to the instrument is a 1/16 to 1/4
tube adapter containing a graphite ferrule. The use of
graphite ferrule on capillaries is recommended.
Compared to metal ferrules, they do no distort the
tube and conform to irregularities in the outside
diameter of the capillary. The inlet end of the
capillary is fitted with a Luer taper fitting, which is the
standard used for syringes. The fitting is not
permanently attached at the factory. For long term
use, the capillary should be sealed into the fitting. A
recess in the back of the fitting is provided for sealant.
Many filters and needles are available that can attach
to the Luer taper. A 0.22
µ
m filter is provided with
the capillary and should be used when possible. The
filter slows the response time of measurements
slightly, but protects against clogging and keeps particles out of the QMS.
Figure 1-2. Back Panel View