Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

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A.4.3 Performance Parameters of Imaging Radiometers The Environmental Research Institute, Michigan (ERIM) Infrared Handbook [13] provides an extensive table of terms and definitions (section 19.1.2) and a list of specimen specifications (section 19.4.1). The section of the Handbook covering infrared imaging systems does not, however, deal with the imager as a quantitative measurement instrument, and so the performance parameters related with temperature measurement need to be added. Some simplifications can be made, which result in some acceptable approximations. Bearing these qualifications in mind, the following definitions of the key performance parameters of infrared thermal scanners are offered: Charlie Chong/ Fion Zhang
• Total field of view (TFOV): the image size, in terms of scanning angle. (example: TFOV = 20°V x 30°H) • Instantaneous field of view (IFOV): the angular projection of the detector element at the target plane; imaging spatial resolution. (example: IFOV= 2 milliradians ) • Measurement spatial resolution (IFOVmeas): the spatial resolution describing the minimum target spot size on which an accurate temperature measurement can be made. (example: IFOVmeas = 5 milliradians) • Frame repetition rate: The number of times every point on the target is scanned in one second. (example: Frame rate = 30 /second) • Minimum resolvable temperature (MRT) (NETD? / MRDT?) : The smallest blackbody equivalent target temperature difference that can be observed; temperature sensitivity (example: MRT=0.1°C @ 30°C target temperature) 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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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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Page 139 and 140: The IR Detectors Infrared detectors
Page 141 and 142: Figure A-15 Spectral Sensitivity of
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Page 151 and 152: Point-sensing instruments for measu
Page 153 and 154: A.3.6.1 Line Scanning The purpose o
Page 155 and 156: A.3.6.2 Two-Dimensional Scanning Th
Page 157 and 158: Opto-mechanical Scanner A typical c
Page 159 and 160: Electronic scanning Electronic scan
Page 161 and 162: Figure A-18 Schematic of a Typical
Page 163 and 164: Applications for infrared FPAs incl
Page 165 and 166: Staring Charlie Chong/ Fion Zhang
Page 167 and 168: A.4.1 Point-Sensing Instruments For
Page 169 and 170: Temperature sensitivity is also cal
Page 171 and 172: EXAM score! thermal resolution (≠
Page 173 and 174: NETD - Noise Equivalent Temperature
Page 175 and 176: Figure A-19 Instrument Speed of Res
Page 177 and 178: Figure A-20 Fields of View of Infra
Page 179 and 180: Figure A-20 Fields of View of Infra
Page 181 and 182: The output requirements are totally
Page 183 and 184: Spectrally selective instruments em
Page 185 and 186: Figure A-21 Spectral Filtering for
Page 187 and 188: Figure A-22 shows a similar solutio
Page 189: A.4.2 Scanners and Imagers.Qualitat
Page 193 and 194: Despite some manufacturers’ claim
Page 195 and 196: A.4.3.1 Temperature Sensitivity, Mi
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 211 and 212: FPA Charlie Chong/ Fion Zhang http:
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Page 215 and 216: A.4.3.3 Speed of Response and Frame
Page 217 and 218: A.4.4 Thermal Imaging Software In o
Page 219 and 220: The newest field-portable instrumen
Page 221 and 222: Appendix B Measuring Emissivity, Re
Page 223 and 224: Figure B-1 Target Radiosity Charlie
Page 225 and 226: The reference emitter technique wor
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
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Classification Of Faults (Guideline
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Reading: Four Emissivity: Understan
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Figure 1 shows a typical three-phas
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Figure IR1: Corresponding infrared
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Thermal radiation and properties of
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The thermal nature of materials. Ma
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So in plain English, when the therm
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Figure 2: Stainless steel block. (a
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Observed with our thermal imager (w
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Can you see my eye glasses in the i
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How can the thermal imager’s read
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When we remove the block from the o
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In this experiment we see that the
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Charlie Chong/ Fion Zhang http://ww
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Using a narrow band filter to measu
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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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