Using The Features - Greenlee THH-100 Instruction Manual

THH-100

Using the Features

To change between Celsius and Fahrenheit:
Press the battery compartment release and pull the door
down. Set the switch to °C or °F. Close the door.
Distance from Target
Infrared thermometers measure the surface temperature of an
object by sensing its emitted, reflected, and transmitted
energy. The sensor collects this energy from the area being
measured (spot size). The spot size varies as the distance to
the target changes. The farther the distance from the area
being targeted, the larger the spot size.
When determining the appropriate distance from the object,
the spot size must be somewhat smaller than the target area.
When accuracy is critical, the spot size should be half as large
as the target. If the spot size is larger than the target size, the
thermometer will pick up the temperature of the background,
resulting in inaccurate readings.
1 2
Object 1 is the correct distance from the unit. Note the target is
slightly larger than the spot size being measured.
Object 2 is too far away. The thermometer also measures the
background because the target is smaller than the instrument's
spot size. This can result in an inaccurate reading.
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