Fluke 56X User Manual download pdf (Page 27)

Infrared Thermometers

Operating the Thermometer

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.

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Fluke 56X User Manual Page 27