Extech Instruments EX845 User Manual page 10

Non-Contact InfraRed Temperature Measurements
1. Set the function switch to the IR Temp position.
2. Aim the infrared sensor (rear of the meter) at
surface to be measured.
3. Press the button in the center of the rotary
function switch to turn on the laser pointer and
identify the surface spot to be measured.
4. The area of the surface to be measured must
spot size as determined by the distance to spot
5. Read the temperature in the display.
Note: See the "Temperature Units" paragraph to select
WARNING: Do not directly view or direct the laser pointer at an eye. Low
power visible lasers do not normally present a hazard, but may present some
potential for hazard if viewed directly for extended periods of time.
IR Spot to Distance Diagram
The 8:1 spot to distance ratio determines the size of the measured surface area with respect to the distance
the meter is held away from the surface.
(10cm)
IR Measurement Notes
1. The object under test should be larger than the spot (target) size calculated by the field of view diagram.
2. If the surface of the object under test is covered with frost, oil, grime, etc., clean before taking
measurements.
3. If an object's surface is highly reflective, apply masking tape or flat black paint to the surface before
measuring.
4. The meter may not make accurate measurements through transparent surfaces such as glass.
5. Steam, dust, smoke, etc. can obscure measurements.
6. To find a hot spot, aim the meter outside the area of interest then scan across (in an up and down
motion) until the hot spot is located.
Diameter of spot
(2.5cm)
(1.25cm)
1"
0.5"
4"
8"
(20cm)
24"
(60cm)
Distance to object
10
be larger than the
size specification.
o o
F or C
(7.5cm)
3"
the