MD 9930 Thermal camera
Temperature Measurement
14
6. Temperature Measurement
All objects radiate infrared energy. The amount of energy radiated is depends on the
surface temperature and the surface emissivity of the object – the higher either of
them, the higher the radiated energy. The thermal camera senses the radiated
infrared energy from the surface of the object and uses this data to calculate a
temperature. Emissivity to be used in calculation has to be set by hand.
Many common objects and materials, such as painted metal, wood, water, skin, and
cloth are very good at radiating energy (have high emissivity) and default setting of
0.95 produces accurate temperature reading.
This simplification does not work on shiny surfaces or unpainted metals as they have
an emissivity of <0.6. These materials are not good at radiating energy and are
classified as low emissivity. To measure them more accurately, emissivity correction
is necessary. Adjusting the emissivity setting results in more accurate temperature
calculation. See
Emissivity Adjustment
for a list of surface emissivity values for
different materials
.
Emissivity Adjustment
The correct emissivity value is an important part of temperature calculation.
Understanding the surface emissivity can help obtain more accurate temperature
measurements.
Material
Emissivity
Water
0.96
Stainless steel
0.14
Aluminium plate
0.09
Asphalt
0.96
Concrete
0.97
Cast iron
0.81
Rubber
0.95
Wood
0.85
Brick
0.75
Tape
0.96
Brass plate
0.06
Human skin
0.98
PVC plastic
0.93
Polycarbonate
0.80
Oxidized copper
0.78
