RayTek 54301 12Appendix

Appendix

12Appendix

Emissivityisameasureofanobject’sabilitytoabsorbandemit

infraredenergy.Itcanhaveavaluebetween0and1.0.Forexamplea

mirrorhasanemissivityof<0.1,whiletheso‐called“Blackbody“

reachesanemissivityvalueof1.0.Ifahigherthanactualemissivity

valueisset,theoutputwillreadlow,providedthetarget

temperatureisaboveitsambienttemperature.Forexample,ifyou

haveset0.95andtheactualemissivityis0.9,thetemperaturereading

willbelowerthanthetruetemperature.

Anobject’semissivitycanbedeterminedbyoneofthefollowing

methods:

1.DeterminetheactualtemperatureofthematerialusinganRTD

(PT100),athermocouple,oranyothersuitablecontact

temperaturemethod.Next,measuretheobject’stemperature

andadjustemissivitysettinguntilthecorrecttemperature

valueisreached.Thisisthecorrectemissivityforthemeasured

material.

2.Ifpossible,applyflatblackpainttoaportionofthesurfaceof

theobject.Theemissivityofthepaintmustbeabove0.98.Next,

measurethetemperatureofthepaintedareausingan

emissivitysettingof0.98.Finally,measurethetemperatureof

anadjacentareaontheobjectandadjusttheemissivityuntil

thesametemperatureisreached.Thisisthecorrectemissivity

forthemeasuredmaterial.