6
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. The laser is used for aiming
purposes only.
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.
Distance and Spot Size
As the distance (D) from the object increases, the spot size (S) of the area measured
by the unit becomes larger.
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 the hot spot.
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 (preset in the unit). Inaccurate readings will
result from measuring shiny or polished metal surfaces. To compensate, cover
the surface to be measured with black 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. (Refer to table on facing page.)
Good Measuring Practices
Holding the meter by its handle, point the IR sensor toward the object whose
temperature is to be measured. The meter automatically compensates for
temperature deviations from ambient temperature. Keep in mind that it will
take up to 30 minutes for the IR sensor to stabilize if going from ambient
temperatures to a much higher (or lower) temperature measurement.
Reminders
• The unit is not recommended for measuring shiny or polished metal surfaces
(stainless steel, aluminum, etc.). See
Emissivity
above.
• The unit cannot measure through transparent surfaces such as glass. It will
measure the surface temperature of the glass instead.
• Steam, dust, smoke, etc. can prevent accurate measurement by obstructing
the unit’s optics.
