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Appendix
12Appendix
12.1DeterminationofEmissivity
Emissivity is a measure of an object’s ability to absorb and emit
infraredenergy.Itcanhaveavaluebetween0and1.0.Forexamplea
mirrorhas anemissivity of< 0.1,while theso‐called“Blackbody“
reachesanemissivityvalueof1.0.Ifahigherthanactualemissivity
value
is set, the output will read low, provided the target
temperatureisaboveitsambienttemperature.Forexample,ifyou
haveset0.95andtheactualemissivityis0.9,thetemperaturereading
willbelowerthanthetruetemperature.
An object’s emissivity canbe determined by oneof thefollowing
methods:
1. DeterminetheactualtemperatureofthematerialusinganRTD
(PT100), a thermocouple, or any other suitable contact
temperature method. Next,measuretheobject’s temperature
and adjust emissivity setting until the correct temperature
valueisreached.Thisisthecorrectemissivityforthemeasured
material.
2. Ifpossible,apply
flatblackpainttoaportionofthesurfaceof
theobject.Theemissivityofthepaintmustbeabove0.98.Next,
measure the temperature of the painted area using an
emissivitysettingof0.98.Finally,measurethetemperatureof
anadjacentareaontheobjectandadjusttheemissivity
until
thesametemperatureisreached.Thisisthecorrectemissivity
forthemeasuredmaterial.
80 MID