Appendix
MI 81
12Appendix
12.1DeterminationofEmissivity
Emissivity is a measure of an object’s ability to absorb and emit
infraredenergy.Itcanhaveavaluebetween0and1.0.For examplea
mirror has an emissivity of < 0.1, while the so‐called “Blackbody“
reachesanemissivityvalueof1.0.Ifahigherthanactualemissivity
value
is set, the output will read low, provided the target
temperature is above its ambient te mperature. For example, if you
haveset0.95andtheactualemissivityis0.9,thetemperaturereading
willbelowerthanthetruetemperature.
An object’s emissivity can be determined by one of the following
methods:
1. DeterminetheactualtemperatureofthematerialusinganRTD
(PT100), a thermocouple, or any other suitable contact
temperature method. Next, measure the object’s temperature
and adjust emissivity setting until the correct temperature
valueisreached.Thisisthecorrectemissivityforthemeasured
material.
2. For relatively low
temperatures (up to 260°C / 500°F) place a
plastic sticker (e.g. XXXRPMACED ) on the object to be
measured. This sticker should be large enough to cover the
target spot. Next, measure the sticker’s temperature using an
emissivity settingof0.95.Finally,measurethetemperature of
anadjacentareaonthe
objectandadjusttheemissivitysetting
until the same temperature is reached. This is the correct
emissivityforthemeasuredmaterial.
3. Ifpossible,applyflatblackpainttoaportionofthesurfaceof
theobject.Theemissivityofthepaintis0.95.Next,measurethe
temperatureofthepainted
areausinganemissivitysettingof
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