RayTek FR, FA Appendix, Determination of Emissivity, Typical Emissivity Values

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Appendix

11 Appendix

11.1 Determination of Emissivity

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

0.95and 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 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.

11.2 Typical Emissivity Values

The following table provides a brief reference guide for determining emissivity and can be used when one of the above methods is not practical. Emissivity values shown in the table are only approximate, since several parameters may affect the emissivity of a material. These include the following:

1.Temperature

2.Angle of measurement

3.Geometry (plane, concave, convex)

4.Thickness

5.Surface quality (polished, rough, oxidized, sandblasted)

6.Spectral range of measurement

7.Transmissivity (e.g. thin films plastics)

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Marathon Series FA/FR

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Contents Marathon FA/FR Series Page Worldwide Headquarters Fluke Service CenterContacts European Headquarters France United KingdomWarranty Table of Contents Milliamp Output Relay Outputs Trigger Fiber Calibration Page Marathon Series FA/FR Safety InstructionsSafety Instructions Theory of Operation for 2‐Color Sensors Product DescriptionProduct Description ModelsLow or Changing Emissivities Partially Obscured TargetsTargets Smaller Than Field of View Measurement Specifications Technical DataTechnical Data FA ModelsGeneral Specifications Electrical Specifications Dimensions Dimensions of Optical HeadFA ModelsAdjustable Mounting Bracket for Optical Head Optical Specifications Standard FocusClose Focus Spot Size Charts for FA models Close FocusStandard Focus Spot Size Charts for FR models Close Focus Spot Size Charts for FR models Scope of DeliverySensor Location Sensor LocationSensor Placement 1‐Color Mode Sensor Placement 2‐Color ModeSensor Placement in 2‐Color Mode Viewing AnglesAcceptable Sensor Viewing Angles Mounting the Sensor InstallationInstallation Aiming Fiber Optic CableInstalling the Electronics Housing Configuring the Sensor CableRemoving the Terminal Block RS232/485 Interface Converter Power SupplyConnecting to a PC Multidrop Installation 4‐Wire Multidrop Installation 2‐WireConnecting to Terminal Block Wiring for 2‐Wire Sensor SetupAddressing Installing of Multiple Sensors in a NetworkWiring Control Panel OperationOperation Mode Selector Button Sequence FA Models Operation ModesSlope 2‐Color Temperature DisplayEmissivity 1‐Color Averaging AVG 4 2C/1C SwitchPeak Hold PKH Valley Hold VAL Overview to Hold FunctionsHold Functions SetpointsDeadband Milliamp Output Ambient Background Temperature Compensation FA ModelsInputs and Outputs Relay OutputsFactory Defaults Factory DefaultsOptions Cooling Platform for Electronics HousingOptions Accessories selection AccessoriesAccessories OverviewAir Purge Collar Protection TubeFitting System Flexible Fitting SystemOrder number Model Available RS232/485 Interface ConvertersIndustrial Power Supply Dimension of Industrial Power SupplyProgramming Guide Command StructureProgramming Guide Remote versus Manual ConsiderationsTransfer Modes Poll ModeBurst Mode Response Time in Setup Mode = + n ⋅15000Command List Command ListXUFR1A Command Examples Command ExamplesTroubleshooting Minor Problems MaintenanceMaintenance TroubleshootingFail‐Safe Operation Error Codes in 1‐Color Mode FA modelsError Codes in 2‐Color Mode FR models Current Output Values in accordance to an Error Examples of failsafe conditionsCleaning the Lens Removing the Fiber Optic Cable from the Optical Head Replacing the Fiber Optic CableRemoving the Fiber Optic Cable Put cable out Mounting the Fiber Optic Cable Attaching the Fiber Optic Cable to the Optical HeadFiber Calibration Dialog for the Calibration of the Fiber Cable Determination of Emissivity AppendixAppendix Typical Emissivity ValuesTypical Emissivity Values Non‐Metals Marathon Series FA/FR55Typical Emissivity Values Metals How to determine slope? Typical SlopesSignal Reduction FR Models Typical Percentage of Allowed Signal Reduction FR1A ModelsMaximum Error Attenuation Influence on AccuracyMarathon Instrument Calibration