Ametek Dycor Dymaxion Mass Spectrometer, User Manual

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5-4 | Dycor Dymaxion Mass Spectrometer
Inlets
The Dymaxion offers a wide variety of inlet options to suit many applications.
The sensor manifold can support up to three different inlets at one time, reducing
the amount of time spent breaking vacuum and changing fittings. All inlets are
physically interchangeable on the same sensor manifold so they can be upgraded
or replaced without disturbing the rest of the system. Figures 5-1 and 5-2 show
two possible inlet configurations: one has manual valves and the other all electro-
pneumatic valves for remote operation.
Mathematically, aperture size and sample chamber pressure are clearly related
through the equation below. This relationship calculates the diameter of the ap-
erture needed to maintain a pressure of 10
-5
Torr in the quadrupole region (Figure
5-3).
Aperture Size (microns) = 50/(sample chamber pressure)
.5
Sampling at Atmosphere
Atmospheric sampling is possible using a capillary tube inlet. The gas inlet is a
fused silica capillary. The diameter and length of the capillary can be changed
to accommodate specific applications, but any adjustments must meet the 10
-5
Torr pressure requirement inside the vacuum system of the Dymaxion. The low
conductance of the capillary decreases the sample gas pressure from atmospheric
pressure to the pressure required by the Dymaxion. A heated capillary is available
to prevent sample condensation
desorption within the capillary.
Inlet Option Descriptions
Capillary
This inlet delivers sample to
the analyzer using a small-bore
capillary with an ID tailored to
suit the sample pressure. It is
available with either a manual or
electropneumatic valve. Figure 5-4 shows the manual and
electropneumatic capillary inlets. These can be mounted
on any Dymaxion manifold.