Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

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The visible spectrum extends from energy wavelengths of 0.4 µm for violet light to about 0.75 µm for red light. For practical purposes of temperature measurement, the infrared spectrum extends from 0.75 µm to about 20 µm. for my ASNT Exam Charlie Chong/ Fion Zhang
Figure A-6 shows the distribution of emitted energy over the electromagnetic spectrum of targets at various temperatures. The sun, at 6000 K, appears white hot because its emitted energy is centered over the visible spectrum with a peak at 0.5 µm. Other targets, such as a tungsten filament at 3000 K, a red-hot surface at 800 K, and the ambient earth at 300 K (about 30°C), are also shown in this illustration. It becomes apparent that, as surfaces cool, not only do they emit less energy, but the wavelength distribution shifts to longer infrared wavelengths. Even though the eye becomes no longer capable of sensing this energy, infrared sensors can detect these invisible longer wavelengths. They enable us to measure the self-emitted radiant energy from even very cold targets and, thereby, determine the temperatures of target surfaces remotely and without contact. Keypoints: The visible spectrum extends from energy wavelengths of 0.4 µm for violet light to about 0.75 µm for red light. For practical purposes of temperature measurement, the infrared spectrum extends from 0.75 µm to about 20 µm. 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
Page 31 and 32: The experience and education recomm
Page 33 and 34: B. Spatial Resolution • the conce
Page 35 and 36: D. Equipment Operation • Be able
Page 37 and 38: The PdM basic examination is more s
Page 39 and 40: Appendix-A The Science Of Thermogra
Page 41 and 42: Erroneous conclusions can have an e
Page 43 and 44: A.2.1 Heat and Temperature What is
Page 45 and 46: To convert changes in temperature o
Page 47 and 48: A.2.3 The Three Modes of Heat Trans
Page 49 and 50: The Fourier Conduction Law: Q/A Q =
Page 51 and 52: A.2.5 Convection Convective heat tr
Page 53 and 54: Figure A-2 Convective Heat Flow Cha
Page 55 and 56: A.2.6 Radiation Radiative heat tran
Page 57 and 58: A.2.7 Radiation Exchange at the Tar
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Page 61 and 62: Figure A-4 Radiative Heat Flow W ε
Page 63 and 64: A.2.8 Specular and Diffuse Surfaces
Page 65 and 66: Specular or Diffuse Surfaces Diffus
Page 67 and 68: Specular and Diffuse Surfaces Confu
Page 69 and 70: Specular reflection is the mirror-l
Page 71 and 72: Reflections off Specular and Diffus
Page 73 and 74: The thermogram of the outside surfa
Page 75 and 76: Steady-state conduction Steady stat
Page 77 and 78: A.3 The Basic Physics of Infrared R
Page 79 and 80: A.3.1 Some Historical Background Th
Page 81: A.3.3 The Target Surface The chart
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Page 87 and 88: Two physical laws define the radian
Page 89 and 90: According to (2), the wavelength at
Page 91 and 92: Figure A-7 Spectral Distribution of
Page 93 and 94: Figure A-8 shows that the instrumen
Page 95 and 96: If the emissivity of a gray body is
Page 97 and 98: Under certain conditions, an error
Page 99 and 100: EXAM score! Non-graybody (colored b
Page 101 and 102: Figure A-10 illustrates the spectra
Page 103 and 104: Figure A-10 Infrared Transmission o
Page 105 and 106: Figure A-11 Infrared Spectral Trans
Page 107 and 108: Figure A-11 shows transmission curv
Page 109 and 110: EXAM score! Glass is opaque λ > 5
Page 111 and 112: Figure A-12 Characteristics of IR T
Page 113 and 114: The characteristics of the window m
Page 115 and 116: IR Lenses - LWIR Len Charlie Chong/
Page 117 and 118: IR Lenses - Fresnel Len Charlie Cho
Page 119 and 120: Figure A-13 Components of an Infrar
Page 121 and 122: Infrared optics are available in tw
Page 123 and 124: All infrared detector-transducers e
Page 125 and 126: Figure A-14 Typical Infrared Radiat
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Page 129 and 130: Thermopile Detector Charlie Chong/
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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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NETD - Noise Equivalent Temperature
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Figure A-19 Instrument Speed of Res
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Figure A-20 Fields of View of Infra
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Figure A-20 Fields of View of Infra
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The output requirements are totally
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Spectrally selective instruments em
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Figure A-21 Spectral Filtering for
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Figure A-22 shows a similar solutio
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A.4.2 Scanners and Imagers.Qualitat
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• Total field of view (TFOV): the
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Despite some manufacturers’ claim
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A.4.3.1 Temperature Sensitivity, Mi
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Figure A-23 Test Setup for MRTD Mea
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A.4.3.2 Spot Size (FOV) , Instantan
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■ A standard 4 bar (slit) resolut
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Both MRTD and MTF are functions of
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Charlie Chong/ Fion Zhang
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IFOVmeas: The slit width at which t
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FPA Charlie Chong/ Fion Zhang http:
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FPA Charlie Chong/ Fion Zhang
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A.4.3.3 Speed of Response and Frame
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A.4.4 Thermal Imaging Software In o
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The newest field-portable instrumen
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Appendix B Measuring Emissivity, Re
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Figure B-1 Target Radiosity Charlie
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The reference emitter technique wor
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1. Apply the reference emitter (E)
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B.2.2 Reflective Emissivity Techniq
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Figure B-3 Using the Reflective Emi
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Figure B-4 Using the Transmittance
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Appendix C Quick Reference Charts A
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MTF Determination Using An Ir Image
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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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