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12. Notes
12-1. How it Works
Infrared thermometers measure the surface temperature of an object.
The unit's optics sense emitted, reflected, and transmitted energy,
which is collected and focused onto a detector. The unit's electronics
translate the information into a temperature reading, which is displayed
on the unit. In units with a laser, the laser is used for aiming purposes
only.
12-2. Field of View
Make sure that the target is larger than the unit's spot size. The smaller
the target, the closer you should be to it. When accuracy is critical,
make sure the target is at least twice as large as the spot size.
12-3. Distance & Spot Size
As the distance (D) from the object increases, the spot size (S) of the
area measured by the unit becomes larger.
12-4. Locating a hot Spot
To find a hot spot aim the thermometer outside the area of interest.
then scan across with an up and down motion until you locate hot spot.
12-5. Reminders
1. Not recommended for use in measuring shinny or polished metal
surfaces (stainless steel, aluminum, etc.). See Emissivity.
2. The unit cannot measure through transparent surfaces such as
glass. It will measure the surface temperature of the glass instead.
3. Steam, dust, smoke, etc., can prevent accurate measurement by
obstructing the unit's optics.
12-6. Emissivity
Emissivity is a term used to describe the energy-emitting
characteristics of materials. Most (90% of typical applications) organic
materials and painted or oxidized surfaces have an emissivity of 0.95
(pre-set in the unit). Inaccurate readings will result from measuring
shinny or polished metal surfaces.
To compensate, cover the surface to be measured with masking tape
or flat black paint. Allow time for the tape to reach the same
temperature as the material underneath it. Measure the temperature of
the tape or painted surface.
11
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