Fluke 561 User Manual download pdf (Page 10)

561 HVACPro

Users Manual

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.

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Fluke 561 User Manual Page 10