Omega Engineering OS533E manual Appendix Determining an Unknown Emissivity

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Appendix: Determining an Unknown Emissivity

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In Appendix A, we showed how emissivity is an important parameter in calculating the temperature of an object via infrared means. In this section we discuss how to determine a specific emissivity value. If you know the material of the object, use Table B- 1 in Appendix B to look up its approximate emissivity. Most organic materials such as plastics, cloth, or wood have an emissivity of about 0.95. For this reason, we use 0.95 as the default emissivity setting in the OS530 Series Thermometer.

For objects of unknown material or for very precise measurements, use one of the following methods to determine a specific emissivity value.

Method 1

1.Measure and record the temperature of the object using a contact temperature probe such as a thermocouple or RTD.

2.Aim the thermometer at the object.

3.Adjust the emissivity until the temperature reading of the thermometer equals the temperature measured in Step 1.

Method 2

1.Heat the object (or at least a sample of the object material) on top of a heating plate to a known temperature. Make sure the thermometer and the air surrounding the heating plate are at the same temperature.

2.Measure the temperature of the object material with the thermometer. Make sure that the object fills the FOV of the thermometer.

3.Adjust the emissivity until the temperature reading of the thermometer equals the known temperature of Step 1.

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Contents User’sGuide Servicing North America Unpacking Instructions Accessories Page Unpacking Instructions Chapter General Description Chapter Maintenance General Description Introduction OS530LE OS530HRE OS530LE-CF OS533E-CF OS534E-CF Features OS523E OS524E Parts of the Thermometer Front of the Thermometer LCDKey General Description General Description Ac Power Operation Installing the BatteriesOperating the Thermometer Field of View PositionsField of View OS534E, OS523E-1 Field of View OS53xE-CF Field of View OS523E-3 Measurement Techniques 11 Recorder Hookup Real Time Mode Active Operation 12. General Operational Block DiagramReal Time Modes 13. Visual Function Flow Chart Using the Trigger Function Adjusting EmissivityUsing the Lock Function Using the Distance Function Must be hard, flat, and reflective to ultrasonic pulseDS = 17. Field of View of Distance Meter HH-DM Calculating Temperature Values Laser Sighting StatusThermocouple Input OS532E, OS533E, OS534E Changing the Temperature from F to C or vice VersaTurning on the Display Backlighting Using the Alarm Functions To set the low alarm value OS533E, OS534E, OS523E, OS524E Use the Ambient Target Temperature Compensation Atcf PC User Application, OS530 Series Operation19. Main Menu Settings Menus 10. Settings Menu21. Typical Temperature Data File PC Interface Commands AsciiString Description Storing Temperature Data on Command OS534E, OS523E, OS524E Logging Temperature Data in Real Time OS523E, OS524E,OS534E Erasing the Temperature Data from Memory Recall Mode Passive Operation ModeRecall Modes Reviewing the Last Parameters Laser Sighting Description Right Side ViewTwo Laser Configurations Operating the Laser SightingLines of Sight of the Laser Sighting and Thermometer Installing and Operating the Sighting Scope Sighting ScopeInstalling the Sighting Scope Safety Warning Maintenance Replacing the BatteriesServicing the Laser Sighting Cleaning the LensCalibrating the Thermometer Troubleshooting Guide Problem SolutionTroubleshooting Guide Problem Troubleshooting Guide Specifications are for all models except where noted SpecificationsGND With Built-in Distance Module Laser Sighting Distance Measuring Built-in-DM Specifications Glossary of Key Strokes Glossary of Key Strokes Thermal Radiation Appendix How Infrared Thermometry Works aBlackbody Calculating Temperature Optics Field of View Metals Appendix Emissivity ValuesNonmetals Appendix Determining an Unknown Emissivity Figure C-1. Determining Emissivity Figure C-2. Determining Emissivity with a Drilled Hole Appendix Determining an Unknown Emissivity Index Field of View Diagrams Recall WARRANTY/DISCLAIMER Temperature PH/CONDUCTIVITY