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Appendix: Determining an Unknown Emissivity
C
C-2
Method 3
1. Use this method to measure objects at temperatures below 500°F
(260°C).
2. Place a large piece of masking tape on the object (or at least a
sample of the object material). Allow time for the masking tape to
reach the object temperature.
3. Set the emissivity of the thermometer to 0.95. Use the thermometer
to measure and record the temperature of the masking tape - Area
‘A’ in Figure C-1. Make sure that the area of the object covered
with masking tape fills the FOV of the thermometer.
Figure C-1. Determining Emissivity
4. Aim the thermometer at Area ‘B’ as shown in Figure C-1 Make
sure that Area ‘B’ is as close as possible to Area ‘A’.
5. Adjust the emissivity of the thermometer until the temperature
reading equals the temperature found in Step 3.
Area 'A'
Target
Area 'B'
Target