Fluke 56X - Manual (Page 27)

Infrared Thermometers
Operating the Thermometer
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Field of View
For accurate measurements, make sure that the target is larger than the unit’s
spot size. The smaller the target, the closer you should be to it (see Figure 8).
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Figure 8. Field of View
Emissivity
Emissivity describes the energy-emitting characteristics of materials. Most
organic materials and painted or oxidized surfaces have an emissivity of
approximately 0.95, the default setting for the thermometer.
To compensate for inaccurate readings that may result from measuring shiny
metal surfaces, you can cover the surface to be measured with electrical tape or
flat black paint (<148 ° C/300 ° F) with emissivity set to 0.95. Allow time for the
tape or paint to reach the same temperature as the surface beneath it. Measure
the temperature of the tape or painted surface.
If you cannot paint or use tape, then you can improve the accuracy of your
measurements by either numerically adjusting emissivity or by using the
Emissivity Menu to access a table of some common materials. The
thermometers have numerically adjustable emissivity from 0.10 to 1.00 that can
be used in conjunction with the emissivities in Tables 3 and 4. Also, the
thermometers have a built-in table of the most common materials that can be set
from the Emissivity Menu. The built-in values are indicated in Tables 3 and 4.
HOLD
The display retains its last infrared measurement for twenty seconds when the
trigger is released, with HOLD appearing on the display. With the probe inserted,
the contact thermometer remains on. To freeze the infrared temperature when a
probe is not inserted, release the trigger until HOLD appears on the display.