Extech Instruments IR400 User Manual (English)

To Next Page

To Previous Page

IR400-en-US_v2.0 7/22

IR Measurement Notes

1. The object under test should be larger than the spot (target) size calculated by the field of view

diagram (printed on the side of the meter and in this guide).

2. Before measuring, be sure to clean surfaces that are covered with frost, oil, grime, etc.

3. If an object's surface is highly reflective, apply masking tape or flat black paint to the surface

before measuring. Allow time for the paint or tape to adjust to the temperature of the surface it is

covering.

4. Measurements can not be made through transparent surfaces such as glass. The surface

temperature of the glass will be measured.

5. Steam, dust, smoke, etc. can obscure measurements.

6. The meter automatically compensates for deviations in ambient temperature. However, it can

take up to 30 minutes for the meter to adjust to extremely wide changes.

7. 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.

Emissivity and IR Measurement Theory

IR Thermometers measure the surface temperature of an object. The thermometer’s optics sense

emitted, reflected, and transmitted energy. The thermometer’s electronics translate the information

into a temperature reading which is then displayed on the LCD.

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. For the Model IR400, the emissivity is set to 0.95 which is correct for 90% of typical IR

measurement applications.

Need help?

Do you have a question about the Extech Instruments IR400 and is the answer not in the manual?

Extech Instruments IR400 Specifications

General

Temperature Range	-4 to 600°F (-20 to 315°C)
Accuracy	±3% of reading or 3.5°F/2°C whichever is greater
Resolution	0.1 °F/°C
Response Time	500 ms
Display	LCD
Power Supply	9V battery
Dimensions	6.5 x 3.5 x 1.5 in (165 x 90 x 38 mm)
Weight	0.6 lb (272 g)
Spectral Response	8 to 14 µm
Display Resolution	0.1 °F/°C
Battery Type	9V battery
Type	Infrared Thermometer
Emissivity	Adjustable from 0.10 to 1.00