Extech Instruments RH401 User Manual page 4

IR Emissivity Adjustment
Emissivity is adjustable from 0.3 to 0.99. The default value is 0.95 which is the typical emissivity
value of many non-metallic surfaces. If the surface to be measured is highly reflective and the
emissivity is not known, cover the surface with paint or tape to improve measurement accuracy. If
the emissivity of the surface is known, follow this procedure to set the value.
1. With the meter on, Press the
will flash on the top left side of the display.
2. Use the
3. When the desired setting appears in the display, press
normal operation.
Material under test
Asphalt
Concrete
Cement
Sand
Soil
Water
Ice
Snow
Glass
Ceramic
Marble
Plaster
Mortar
Brick
Spot to Distance Ratio
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.
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key twice to enter the Emissivity setting procedure.
up key and the
Emissivity Factors for Common Materials
Emissivity
0.90 to 0.98
0.94
0.96
0.90
0.92 to 0.96
0.92 to 0.96
0.96 to 0.98
0.83
0.90 to 0.95
0.90 to 0.94
0.94
0.80 to 0.90
0.89 to 0.91
0.93 to 0.96
GlobalTestSupply
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down key to adjust the value.
Material under test
Cloth (black)
Skin (human)
Lather
Charcoal (powder)
Lacquer
Lacquer (matt)
Rubber (black)
Plastic
Timber
Paper
Chromium Oxides
Copper Oxides
Iron Oxides
Textiles
4
again to save and return back to
Emissivity
0.98
0.98
0.75 to 0.80
0.96
0.80 to 0.95
0.97
0.94
0.85 to 0.95
0.90
0.70 to 0.94
0.81
0.78
0.78 to 0.82
0.90
RH401-en-GB_ V1.7 1/17
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