Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

More documents

Recommendations

Info

The block appears to vary in temperature from about 92 ºF to 110 ºF – and you can see the image of my face in the warm metal surface even more clearly than before. Using a thermocouple, we measure the surface temperature and find that it’s actually 169 ºF (see Figure 2a). Figure 2a: DMM with thermocouple, measuring surface temperature of the steel block. Charlie Chong/ Fion Zhang http://reliableplant.com/Read/14134/emissivity-underst-difference-between-apparent,-actual-ir-temps
How can the thermal imager’s readings appear reasonable when the metal part is at room temperature and be so wrong (still producing a mirror image of my face on the hot surface) when the part is 169 ºF? At room temperature, the block appears to be room temperature because the block is primarily reflecting the thermal radiation from everything around it. Since the ambient temperature in the room is in the 70s, the reflection from the surface of the block appears also to be similar. When the same part is heated in the oven, the part becomes much hotter than the surroundings, so the thermal imager is able to see an increase in radiant energy, albeit 尽然 much lower in apparent temperature because of the low emissivity value of the surface. Let’s modify our experiment to better demonstrate what the thermal imager sees. We take another stainless steel block and paint half of it with a flat black paint (flat black paint has an emissivity of 1 or 0.98 to be a little precise) and bake it (in a slightly warmer oven) another three hours (Figure 3, Figure IR3). Charlie Chong/ Fion Zhang http://reliableplant.com/Read/14134/emissivity-underst-difference-between-apparent,-actual-ir-temps
Page 1 and 2:
Infrared Thermal Testing Reading VI
Page 3 and 4:
6.1 Basic Elements An in-house prog
Page 5 and 6:
6.1.4 Responsibilities This section
Page 7 and 8:
IR Viewing Window - Opaque Polymer
Page 9 and 10:
6.1.8 Acceptance Criteria All surve
Page 11 and 12:
6.1.9 Reporting Criteria A rigid pr
Page 13 and 14:
6.1.10 Qualification of Personnel P
Page 15 and 16:
EPRI Licensed Material Basic Elemen
Page 17 and 18:
Page 19 and 20:
Page 21 and 22:
Page 23 and 24:
Page 25 and 26:
7. TRAINING AND CERTIFICATION This
Page 27 and 28:
Recommended training and certificat
Page 29 and 30:
■ 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
Page 59 and 60:
Charlie Chong/ Fion Zhang
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 and 82:
A.3.3 The Target Surface The chart
Page 83 and 84:
Figure A-6 shows the distribution o
Page 85 and 86:
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
Page 127 and 128:
Germanium Len Charlie Chong/ Fion Z
Page 129 and 130:
Thermopile Detector Charlie Chong/
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
The IR Detectors Infrared detectors
Page 141 and 142:
Figure A-15 Spectral Sensitivity of
Page 143 and 144:
The Mercury- Cadmium-telluride (Hgc
Page 145 and 146:
The Mercury- Cadmium-Telluride (HgC
Page 147 and 148:
Page 149 and 150:
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 and 190:
A.4.2 Scanners and Imagers.Qualitat
Page 191 and 192:
• Total field of view (TFOV): the
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
Page 205 and 206:
Page 207 and 208:
IFOVmeas: The slit width at which t
Page 209 and 210:
Page 211 and 212: FPA Charlie Chong/ Fion Zhang http:
Page 213 and 214: FPA Charlie Chong/ Fion Zhang
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
Page 241 and 242: Classification Of Faults (Guideline
Page 243 and 244: Charlie Chong/ Fion Zhang
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
Page 261: Can you see my eye glasses in the i
Page 265 and 266: When we remove the block from the o
Page 267 and 268: In this experiment we see that the
Page 269 and 270: Charlie Chong/ Fion Zhang http://ww
Page 271 and 272: Using a narrow band filter to measu
Page 273 and 274: Emissivity, the variable’s variab
Page 275 and 276: Emissivity and electrical equipment
Page 277 and 278: In manufacturing processes, steel o
Page 279 and 280: In this case, we have another power
Page 281 and 282: Figure IR1: Corresponding infrared
Page 283 and 284: Figure 7: Measuring the loads on a
Page 285 and 286: Summary Predictive maintenance PDM
Page 287 and 288: It is much like most endeavors in l
Page 289 and 290: Good Luck Charlie Chong/ Fion Zhang
Page 291: Charlie https://www.yumpu.com/en/br
show all

Understanding Infrared Thermography Reading 7 Part 2 of 2.pdf

Create successful ePaper yourself

Delete template?

Save as template?