Emerson Rosemount 370XA System Reference Manual page 25

System Reference Manual
7P00370-H01
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Heater cap
Controls the thermal environment surrounding the analytical
components of the module, which is crucial to ensure the
reliable and repeatable analysis.
Chromatography columns
Separates the sample gas into its component compounds so
that they can be detected and measured. The 370XA's pre-
coiled, micro-packed columns contain active materials that
selectively impede the flow of individual component
compounds based on their boiling point, so that components
with lower boiling points take longer to travel through the
columns than components with higher boiling points. The
370XA uses four chromatograph columns and a single
restrictor column.
Analytical valves
Manipulates the flow of carrier and sample gases through the
columns and the detector. The analytical valves use
diaphragm-actuated pistons to block or release the flow of the
gases between adjacent ports on the valve. The majority of
service on the maintainable module will most likely involve
replacing the diaphragms and cleaning the sealing surfaces of
the analytical valves.
Detector
Detects and measures the components of the sample gas after
the components are separated by the columns. A single
thermal conductivity detector (TCD) has two thermistors that
respond to the difference in thermal conductivity between the
carrier gas and the separated components.
370XA Gas Chromatograph
APRIL 2014