Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

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B.2 Measuring Emissivity There are several common techniques for the measurement of emissivity using a single band radiometer, two of which are illustrated below. ■ The first technique, known as the reference emitter technique, is accomplished by direct comparison with a known emitter at the same temperature. ■ The second technique, known as the reflective emissivity technique, is accomplished by calculating emissivity indirectly using measured values of reflectance (and transmittance if applicable). Charlie Chong/ Fion Zhang
The reference emitter technique works well when the target is at a different temperature than the background, such as in the case of a steam inlet valve whose body is at system operating temperature, while the applied emissivity reference is at the same temperature as the target. The reflective emissivity technique works well for smooth surfaces such as an electrical connection. The reflective emissivity technique is independent of target temperature, although the temperature of the target must remain constant throughout the measurement. A third, field-type method for estimating the effective emissivity of a specific target under specific conditions, is described in Section 3.3.3 and is illustrated in Appendix C, Plate 5. Charlie Chong/ Fion Zhang
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Infrared Thermal Testing Reading VI
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6.1 Basic Elements An in-house prog
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6.1.4 Responsibilities This section
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IR Viewing Window - Opaque Polymer
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6.1.8 Acceptance Criteria All surve
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6.1.9 Reporting Criteria A rigid pr
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6.1.10 Qualification of Personnel P
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EPRI Licensed Material Basic Elemen
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7. TRAINING AND CERTIFICATION This
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Recommended training and certificat
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■ Level II A Level II infrared th
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The experience and education recomm
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B. Spatial Resolution • the conce
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D. Equipment Operation • Be able
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The PdM basic examination is more s
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Appendix-A The Science Of Thermogra
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Erroneous conclusions can have an e
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A.2.1 Heat and Temperature What is
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To convert changes in temperature o
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A.2.3 The Three Modes of Heat Trans
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The Fourier Conduction Law: Q/A Q =
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A.2.5 Convection Convective heat tr
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Figure A-2 Convective Heat Flow Cha
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A.2.6 Radiation Radiative heat tran
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A.2.7 Radiation Exchange at the Tar
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Charlie Chong/ Fion Zhang
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Figure A-4 Radiative Heat Flow W ε
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A.2.8 Specular and Diffuse Surfaces
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Specular or Diffuse Surfaces Diffus
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Specular and Diffuse Surfaces Confu
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Specular reflection is the mirror-l
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Reflections off Specular and Diffus
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The thermogram of the outside surfa
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Steady-state conduction Steady stat
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A.3 The Basic Physics of Infrared R
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A.3.1 Some Historical Background Th
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A.3.3 The Target Surface The chart
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Figure A-6 shows the distribution o
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Charlie Chong/ Fion Zhang
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Two physical laws define the radian
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According to (2), the wavelength at
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Figure A-7 Spectral Distribution of
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Figure A-8 shows that the instrumen
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If the emissivity of a gray body is
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Under certain conditions, an error
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EXAM score! Non-graybody (colored b
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Figure A-10 illustrates the spectra
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Figure A-10 Infrared Transmission o
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Figure A-11 Infrared Spectral Trans
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Figure A-11 shows transmission curv
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EXAM score! Glass is opaque λ > 5
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Figure A-12 Characteristics of IR T
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The characteristics of the window m
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IR Lenses - LWIR Len Charlie Chong/
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IR Lenses - Fresnel Len Charlie Cho
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Figure A-13 Components of an Infrar
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Infrared optics are available in tw
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All infrared detector-transducers e
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Figure A-14 Typical Infrared Radiat
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Germanium Len Charlie Chong/ Fion Z
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Thermopile Detector Charlie Chong/
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The IR Detectors Infrared detectors
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Figure A-15 Spectral Sensitivity of
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The Mercury- Cadmium-telluride (Hgc
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The Mercury- Cadmium-Telluride (HgC
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Point-sensing instruments for measu
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A.3.6.1 Line Scanning The purpose o
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A.3.6.2 Two-Dimensional Scanning Th
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Opto-mechanical Scanner A typical c
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Electronic scanning Electronic scan
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Figure A-18 Schematic of a Typical
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Applications for infrared FPAs incl
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Staring Charlie Chong/ Fion Zhang
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A.4.1 Point-Sensing Instruments For
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Temperature sensitivity is also cal
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EXAM score! thermal resolution (≠
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Page 175 and 176: Figure A-19 Instrument Speed of Res
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Page 179 and 180: Figure A-20 Fields of View of Infra
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Page 189 and 190: A.4.2 Scanners and Imagers.Qualitat
Page 191 and 192: • Total field of view (TFOV): the
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Page 197 and 198: Figure A-23 Test Setup for MRTD Mea
Page 199 and 200: A.4.3.2 Spot Size (FOV) , Instantan
Page 201 and 202: ■ A standard 4 bar (slit) resolut
Page 203 and 204: Both MRTD and MTF are functions of
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Page 207 and 208: IFOVmeas: The slit width at which t
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Page 215 and 216: A.4.3.3 Speed of Response and Frame
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Page 219 and 220: The newest field-portable instrumen
Page 221 and 222: Appendix B Measuring Emissivity, Re
Page 223: Figure B-1 Target Radiosity Charlie
Page 227 and 228: 1. Apply the reference emitter (E)
Page 229 and 230: B.2.2 Reflective Emissivity Techniq
Page 231 and 232: Figure B-3 Using the Reflective Emi
Page 233 and 234: Figure B-4 Using the Transmittance
Page 235 and 236: Appendix C Quick Reference Charts A
Page 237 and 238: MTF Determination Using An Ir Image
Page 239 and 240: Measuring And Setting Effective Emi
Page 241 and 242: Classification Of Faults (Guideline
Page 245 and 246: Reading: Four Emissivity: Understan
Page 247 and 248: Figure 1 shows a typical three-phas
Page 249 and 250: Figure IR1: Corresponding infrared
Page 251 and 252: Thermal radiation and properties of
Page 253 and 254: The thermal nature of materials. Ma
Page 255 and 256: So in plain English, when the therm
Page 257 and 258: Figure 2: Stainless steel block. (a
Page 259 and 260: Observed with our thermal imager (w
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Page 263 and 264: How can the thermal imager’s read
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Page 267 and 268: In this experiment we see that the
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Page 271 and 272: Using a narrow band filter to measu
Page 273 and 274: Emissivity, the variable’s variab
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Emissivity and electrical equipment
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In manufacturing processes, steel o
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In this case, we have another power
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Figure IR1: Corresponding infrared
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Figure 7: Measuring the loads on a
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Summary Predictive maintenance PDM
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It is much like most endeavors in l
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Good Luck Charlie Chong/ Fion Zhang
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Charlie https://www.yumpu.com/en/br
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