Fluke Ti20 user manual How to assure accurate temperature measurement?, What is emissivity?

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Ti20

Users Manual

 

 

Visible

 

Gamma

X-Rays

Ultraviolet Infrared

Radio

Rays

EHF SHF UHF VHF HF MF LF VLF

 

 

 

 

0.1 A 1 A 1 UA

100 A 0.

 

1 µ 10 µ 100 µ 0.1 cm 1 cm 10 cm 1 m 10 m 100 m 1 km 10 km 100 km

1 µ

Wavelength

Infrared Measurement Region

0.4

0.6

0.8

1

1.5

2

3

4

6

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10

15

20

30

Wavelength µm

dag011f.eps

Figure B-1. Infrared Measurement Region

Q. How to assure accurate temperature measurement?

A. A solid understanding of infrared technology and its principles lies behind accurate temperature measurement. When the temperature is measured by a non-contact device the IR energy emitted from the measured object passes through the optical system of the thermometer or thermal imager and is converted to an electrical signal at the detector. This signal is then displayed as a temperature reading and/ or thermal image. There are several important factors that determine accurate measurement. The most important factors are emissivity, distance to spot ratio, and field- of-view.

Q. What is emissivity?

A. All objects reflect, transmit and emit energy. Only the emitted energy indicates the temperature of the object. When IR thermometers or thermal imagers measure the surface temperature they sense all three kinds of energy, therefore all thermometers have to be adjusted to read emitted energy only. Measuring errors are often caused by IR energy being reflected by light sources.

Some IR thermometers and thermal imagers allow you to change the emissivity in the unit. The value of emissivity for various materials can be looked up in published emissivity tables.

Other units have a fixed, pre-set emissivity of 0.95, which is the emissivity value for most organic materials and painted or oxidized surfaces. If you are using a thermometer or thermal imager with a fixed emissivity to measure the surface temperature of a shiny object you can compensate by covering the surface to be measured with masking tape or flat black paint. Allow time for the tape or paint to reach the same temperature as the material underneath. Measure the temperature of the taped or painted surface. That is the true temperature.

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Contents Ti20 Limited Warranty and Limitation of Liability Table of Contents Ti20 List of Tables Ti20 List of Figures Ti20 Introduction Getting StartedContacting Fluke Safety Information SymbolsTi20 Laser Warning LabelsStandard Accessories Unpacking the ImagerUnpacking the Imager Features and Controls Ti20Focusing the Imager Operating the ControlsTi20 Understanding the TriggerUsing the AC Power Adapter Using the AC Power AdapterUsing the Battery Charger Charging and Replacing the BatteriesInstalling or Replacing the Batteries Replacing the Battery PackAttaching the Wrist Strap Attaching the Wrist StrapConnecting the USB Cable Inputs and ConnectionsCleaning the Case CleaningMounting the Imager on a Tripod Cleaning the Lens Ti20 Basic Operation Turning the Imager On and OffUnderstanding the Home Display Imager Home Display ZonesContents of the Home display is described in Table Aiming and Activating the Laser Capturing Images Comparing Frozen Images to Stored ImagesAdjusting the Backlight Setting the Temperature Scale Setting the LevelPress Flevel to access the set Level function Using Distance to Spot Size Ratio DS Adjusting the SpanManually Activating the Calibration Flag FOV Ambient Temperature Derating and Thermal Shock Environmental ConditionsTape method EmissivityContact thermometer method Reflected Temperature Compensation Reflected Temperature CompensationTi20 Data Management and Storage Advanced Imager OperationViewing Stored Images Deleting Images Selecting a Palette Adjusting Emissivity Press FNto access the Adjust Emissivity display Adjusting Reflected Temperature Compensation Values Setting Alarm Limits Dag124f.bmp Adjusting Sleep Mode Ti20 Appendices Page Glossary Calibration Display ResolutionBlackbody Calibration SourceFull Scale Field of View FOVFocus Point or Distance Full Scale AccuracyMicron or µm Optical ResolutionLevel Minimum spot sizeRelative Humidity Reflected Temperature CompensationResolution RepeatabilityTemperature Coefficient or Ambient Derating Storage Temperature RangeTemperature Temperature ResolutionBasics of Infrared Measurement Why use non-contact infrared thermometers?How does IR work? How to assure accurate temperature measurement? What is emissivity?How to take temperature measurement? What is the distance to spot ratio?What are some uses for non-contact thermometers? Ti20 Typical Emissivity Values Table C-1. Emissivity Values for Metals Material To 14 µm Table C-1. Emissivity Values for Metals Material To14 µm Tin Unoxidized 0.3 Titanium Polished Typical Emissivity Values Ti20 Specifications ThermalOther
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