Extech Instruments 42525 User Manual page 5

Operating Instructions
Emissivity Considerations
The amount of IR energy emitted by an object is proportional to an object's temperature
and its ability to emit energy. This ability is known as emissivity and is based upon the
material of the object and its surface finish. Emissivity values range from 0.1 for a very
reflective object to 1.00 for a flat black finish. The 42525 senses IR energy and calculates
the temperature based upon the amount of IR energy it receives using a factory default
emissivity setting of 0.95 (this setting covers 90% of applications). The user can manually
adjust the emissivity setting if desired. This procedure is described later in this manual.
Infrared Measurement Procedure
1. Power the meter by setting the POWER OFF/ON switch to the ON position.
2. Set the IR / TYPE K switch to the IR position.
3. Set the temperature units (degrees C or F) using the C/F button.
4. Set the resolution (1 or 0.1) using the resolution select switch.
5. Point the IR sensor toward the object under test.
6. The object under test should be larger than the spot size calculated by field/distance
chart (see diagram below).
7. Read the LCD display for the temperature measurement.
Distance to Object (inches)
6
3
0.5
1.0
Diameter of Spot (inches)
5
12
Laser Pointer
2.0
Model 42525 Version 2.2 October 2003