RayTek ThermoView Ti30 user manual Emissivity, Reflected Temperature Compensation

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Emissivity

Emissivity is the measure of an object's ability to emit infrared energy. Emitted infrared energy is exponentially proportional to the temperature of the object. Emissivity can have a value from 0 (shiny mirror, perfect reflector) to 1.0 (blackbody, perfect emitter). Most organic, painted, or oxidized surfaces have emissivity values close to 0.95. If you are performing qualitative inspections with your imager, leave the emissivity set at 1.0. If you need to measure actual temperature values, set the emissivity value according to the emissivity of the material the object you are measuring is made of. Again, if you need accuracy, you will need to find the emissivity value of the material before taking the measurement. See Table 1 on page 68 and Table 2 on page 69 for the emissivity values for the most common materials.

There are a couple of methods that help you to find the emissivity value of materials:

ξ Tape method: this method requires the usage of the Scotch® brand PVC tape (emissivity value 0.97) or equivalent. Cover the surface you want to measure with tape. Wait some seconds for the temperature to stabilize. Set the emissivity of the imager at

0.97and measure the temperature. Make a note of the temperature value. Then, remove the tape and measure the new temperature value. Adjust the emissivity accordingly until the temperature value found previously is displayed on the unit. This emissivity value is the one of the material being measured. This method is good for objects that are at low temperatures (under 100θC (212θF)), not electrically energized and not in motion.

ξ Contact thermometer method: this method will need a contact probe and good quality temperature meter. Initially, use the contact probe temperature meter to measure the temperature of the object you want to know the emissivity value, allowing time for the contact probe to stabilize (this may take up to a minute). Make a note of the temperature value. Adjust the emissivity on the imager accordingly until the temperature value found previously with contact probe temperature meter is displayed on the imager display. This emissivity value is the one of the material being measured. This method is good for

objects that are at moderately high temperatures (under 250θC (482θF)), not electrically energized and not in motion.

To set or change the Emissivity value, complete the following:

1.Put the ThermoView Ti30 imager in regular Measurement mode.

2.Press the MODE button once. At this point you will be able to adjust Emissivity.

3.Set the Emissivity value to the proper value, according to the target material, by pressing the Up and Down buttons.

Reflected Temperature Compensation

Targets that have low emissivities will reflect energy from nearby objects. This additional reflected energy is added to target’s own emitted energy and may result in inaccurate readings (see Figure 31 below). In some situations objects near the target (machines,

July 1, 2003

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Contents User’s Manual ThermoView Ti30Contents Qualitative and Quantitative Temperature Measurements Appendix B Infrared Theory Q&A Glossary Warranty Information Customer Service Contact Information Introduction Netd Quick Specifications TableUnpacking Your New Imager First, the Batteries Removing the Battery PackBattery Packs Normal Charge Cycle Charging the Rechargeable Battery PackDocking Station LED Indicators Attaching the Wrist Strap Getting StartedDisplaying Images Turning the Unit OnInformation Screen Normal Mode Keypad Settings and ControlsThermoView Imager Settings Switches icons not shown Laser On/Off Toggle Button ThermoView Imager Settings SwitchesLaser Aperture and Optical Channel JapanesePalette Switch LCD Backlight Illumination SwitchMeasurement Mode Switch Centigrade/Fahrenheit Toggle ButtonFocus Wheel Gain and Level ThumbwheelsAutomatic Semi Automatic Level pointLocation of the Focus Wheel TriggerMain Loop Man Machine Interface Flow ChartsImage Recording Procedure Emissivity Adjustment Procedure July 1 Version Recording an Image Quick Image Fix Procedure Array Recalibration ProcedureRetrieving an Image Retrieve ModeDownloading and Looking at Images Installing the SoftwareHooking Up the Docking Station Connecting the Docking Station to Your ComputerConnecting the USB Connector to the USB Port InsideIR Main Screen at Program Launch Sync button Downloading ImagesDownload Data Screen Saving ImagesContents of Images Folder Setting the Imager ClockJuly 1 Version Looking at Your Downloaded Images Field USB PortViewing Thumbnail Images Viewing a Single Image Obtaining the Best Image Importance of FocusingSelecting the Color Palette Selecting the Measurement ModeLevelGain Min Level  Gain Max Level  Gain Tip Distance to Target Spot Ratio Qualitative and Quantitative Temperature MeasurementsField-of-View Optical DiagramDS ratio D / S = Environmental Conditions Ambient TemperaturesEmissivity Reflected Temperature CompensationReflected Temperature Compensation File Management Organizing Your DataUploading Data to Your ThermoView Ti30 Imager Uploading Data to the ImagerEditing Data Before Upload RTC OFF Single Image Screen Analyzing Your DataScale Limits Sample Image at Original Scale Limits Isotherms Sample Image at Original Isotherm SettingAdditional Image Analysis Tools Temperature Table TabProfile Tab Temperature TableProfile Tab Histogram TabNew Folder Menu BarExit ThermoView Imager InfoFahrenheit CelsiusExport Image Export Temperature TableCreate Report HistogramContents Copy Profile ChartCascade Tile HorizontalThermographic Report Reporting Your FindingsAppendix a Technical Reference Imager Accuracy ChartTypical Emissivity Values Imager Reading Error vs Source DSAluminum Unoxidized Ni-Cu Gob Appendix B Infrared Theory Q&A Why use noncontact infrared thermometers?How does IR work? Emissivity How to assure accurate temperature measurement?Field-of-view Distance to spot ratioWhat are the most popular applications? How to take temperature measurement?Glossary Blackbody Background TemperatureCalibration Calibration SourceDrift Display ResolutionEMI/RFI Noise Far FieldFull Scale Focus Point or DistanceFull Scale Accuracy Gray BodyLoop LaserMicron or µm Minimum spot sizeNon-Gray Body Optical ResolutionOptical Pyrometer Pyroelectric DetectorResolution Reflected Temperature CompensationRelative Humidity RepeatabilityTemperature Storage Temperature RangeTemperature Coefficient or Ambient Derating Spectral ResponseThermal Shock Temperature ResolutionTime Constant Transfer Standard
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