Siemens Maxum II Service Manual

Flame Ionization Detector
4
The Flame Ionization Detector (FID)
is a very sensitive detector that is
used for measuring hydrocarbons. It
responds to most carbon containing
compounds. Using a methanator,
the FID can also detect carbon mon‐
oxide (CO) and carbon dioxide
(CO
2
). Operation of the FID involves
combustion of the sample com‐
pounds. This combustion produces
ions. The ions are captured by an
electrode in the FID, creating an
electrical signal current.
The FID is very sensitive to all types
of hydrocarbons and to any contam‐
ination in gases or supply lines. For
a high signal/noise ratio, ensure that
the supply gases (Hydrogen and Air)
and carrier gas have a purity of
99.999% and hydrocarbon content
below 2 ppm*. For special detection
sensitivity, filter supply gases using
a molecular sieve filter. If plant air is
used, a catalytic Air Treater is strong‐
ly recommended to reduce the pos‐
sible hydrocarbon content of the air.
The FID is shown at right without
cover or insulation.
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* 2 ppm refers to the total hydrocarbon concentration expressed as methane.
Maxum Edition II Detectors
Service Manual, May 2018, A5E42019847001 31

Siemens Maxum II Specifications

General

Category	Gas Chromatograph
Measurement Principle	Gas Chromatography
Communication Protocols	Modbus, Ethernet, Profibus
Operating Temperature	-20°C to 55°C
Power Supply	24 VDC or 100-240 VAC
Mounting	rack mount
Applications	Refinery, chemical, petrochemical, natural gas
Detectors	Thermal Conductivity Detector (TCD), Flame Ionization Detector (FID)
Sample Inlets	Multiple
Dimensions	Varies by configuration (e.g., 19" rack mount)