FLIR MR77, User Manual

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5 Operation
3. Press the button repeatedly to cycle through the display of relative hu-
midity, dew point temperature, and mixing ratio.
• Relative humidity: The indicator is displayed and the reading is
displayed in percent (%).
• Dew point temperature: The indicator is displayed and the reading
is displayed in ℃ or ℉ , depending on the unit setting.
• Mixing ratio: The reading is displayed in grains per pound (GPP) or grams
per kilogram (g/kg), depending on the unit setting.
5.4 IR temperature measurements
IR temperature measurements can be performed in all operating modes.
The meter is equipped with a laser pointer diode, which is used as a targeting
pointer for the IR temperature measurements. The target of the measurement
should be larger than the size of the laser beam spot. As the distance from an ob-
ject increases, the spot size of the area measured by the meter becomes larger.
The meter’s field of view ratio is 8:1, meaning that if the meter is 8 inches (20 cm)
from the target, the diameter (spot) of the object under test must be at least 1
inch ( 2.54 cm). Refer to Figure 5.1.
Figure 5.1 IR spot-to-distance ratio
IR measurement notes:
• The object under test should be larger than the than the size of the laser
beam spot.
• If the surface of the object under test is covered with frost, oil, grime, etc.,
clean the surface before measuring.
• If the surface of the object is highly reflective, apply masking tape or flat black
paint to the surface before measuring.
• The meter may not make accurate measurements through transparent surfa-
ces such as glass.
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