ProductDescription
2 MarathonSeriesFA/FR
2ProductDescription
TheMarathonFA/FR fiber optic seriesofinstrumentsare high‐performance infrared thermometers.
Eachhas a frontend consisting ofa small, fixed focusopticalheadcoupledto a rugged fiber optic
cable wrapped with a flexible stainless steel sheath. The fiber optic cable attaches to an electronics
enclosure,whichcan
bemountedawayfromthehot,hostileenvironment.Theelectronicsenclosure
canbeconnectedtoacomputerwithitstwo‐wayRS485interface.
Temperaturemeasurementscanbetakenusingeitherofthefollowingmodes:
• 1‐color mode (FA and FR sensors) – for standard temperature measurements. The 1‐color
mode
isbestformeasuringthetemperatureoftargetsinareaswherenosightingobstructions,
eithersolidor gaseous,exist.The1‐colormodeisalsobestwherethetargetcompletelyfills
the measurement spot and where the background or foreground are higher in temperature
thanthetarget.
• 2‐colormode
(FRsensorsonly)–temperaturesaredeterminedfromtheratiooftwoseparate
andoverlappinginfraredbands.The2‐colormodeis best formeasuringthetemperatureof
targets that are partially obscured (either intermittently or permanently) by other objects,
openings,screens,orviewingwindowsthatreduceenergy,andby
dirt,smoke,orsteamin
theatmosphere.The2‐colormodecanalsobeusedontargetsthatdonotcompletelyfillthe
measurementspot,providedthebackgroundismuchcoolerthanthetarget.
Eachmodeloperatesasatemperaturemeasurementsubsystemconsistingofopticalelements,spectral
filters,detector,and
digitalelectronics.Allcomponentsarewater‐tightNEMA‐4(IEC529,IP65)rated
andarebuilttooperateona100percentdutycycleinindustrialenvironments.Simultaneousanalog
and digital outputs consist of standardized current signals commonly available for use with
computers,controllers,recorders,alarms,orA/Dinterfaces.
Model Description
FA1A, FA1B, FA1C 1-color-sensor in spectral range of 1 µm
different temperature ranges
FA1G 1-color-sensor specifically designed for measuring glass
FA2A, FA2B 1-color-sensor in spectral range of 1.6 µm
different temperature ranges
FR1A, FR1B, FR1C 2-color-sensor in spectral range of 1 µm (nominal)
different temperature ranges
Table1:Models
2.1TheoryofOperationfor2‐ColorSensors
Two‐color ratio technologymakes possibleaccurate and repeatable temperaturemeasurements that
are free from dependence on absolute radiated energy values. In use, a 2‐color sensor determines
temperaturefromthe ratio ofthe radiated energies in twoseparate wavelength bands (colors).The
benefits of 2‐color sensors are that accurate
measurements can be made under the following
conditions:
• Whenthefieldofviewtothetargetispartiallyblockedorobscured.
• Whenthetargetissmallerthanthesensor’sfieldofview.
• Whentargetemissivitiesareloworchangingbythesamefactorinbothwavelengthbands.
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