Fluke 561 - Manual (Page 10)

561 HVACPro
Users Manual
6
How the Thermometer Works
Infrared thermometers measure the surface temperature of an opaque object. The Thermometer’s optics
sense infrared energy, which is collected and focused onto a detector. The Thermometer’s electronics then
translate the information into a displayed temperature reading which appears on the display. The laser is
used for aiming purposes only.
Operating the Thermometer
The Thermometer turns on when you press the trigger. The Thermometer turns off when no activity is
detected for 7 seconds.
To measure temperature, aim the Thermometer at the target, pull and hold the trigger. Release the trigger
to hold a temperature reading.
Be sure to consider distance-to-spot size ratio and field of view. The laser is used for aiming only.
Locating a Hot or Cold Spot
To find a hot or cold spot, aim the Thermometer outside the target area. Then, slowly scan across the area
with an up and down motion until you locate the hot or cold spot. See Figure 4.
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Figure 4. Locating a Hot or Cold Spot
Distance and Spot Size
As the distance (D) from the target being measured increases, the spot size (S) of the area measured by the
unit becomes larger. The spot sizes indicates 90 % encircled energy. The maximum D:S is obtained when
the Thermometer is 900 mm (36 in) from the target resulting in a spot size of 75 mm (3 in). See Figure 5.