Fluke VT04 Manual - Page 22

Temperature Measurement

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VT02, VT04 Users Manual Temperature Measurement All objects radiate infrared energy. The quantity of energy radiated is based on the actual surface temperature and the surface emissivity of the object. The Product senses the infrared energy from the surface of the object and uses this data to calculate an estimated temperature value. Many common objects and materials such as painted metal, wood, water, skin, and cloth are very good at radiating energy and it is easy to get relatively accurate measurements. For surfaces that are good at radiating energy (high emissivity), the emissivity factor is ≥90 % (0.90). This simplification does not work on shiny surfaces or unpainted metals as they have an emissivity of

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VT02, VT04
Users Manual
14
Temperature Measurement
All objects radiate infrared energy. The quantity of energy radiated is based on
the actual surface temperature and the surface emissivity of the object. The
Product senses the infrared energy from the surface of the object and uses this
data to calculate an estimated temperature value. Many common objects and
materials such as painted metal, wood, water, skin, and cloth are very good at
radiating energy and it is easy to get relatively accurate measurements. For
surfaces that are good at radiating energy (high emissivity), the emissivity
factor is
≥
90 % (0.90). This simplification does not work on shiny surfaces or
unpainted metals as they have an emissivity of <60 % (0.60). These materials
are not good at radiating energy and are classified as low emissivity. To more
accurately measure materials with a low emissivity, an emissivity correction is
necessary. Adjustment to the emissivity value will usually allow the Product to
calculate a more accurate estimate of the actual temperature.
Note
Surfaces with an emissivity <0.60 make reliable and consistent
determination of actual temperatures problematic. The lower the
emissivity, the more potential error is associated with the temperature
measurement calculations of the Product, even when emissivity and
reflected background adjustments are attempted and performed
properly.
Warning
To prevent personal injury, see emissivity information for actual
temperatures. Reflective objects result in lower than actual
temperature measurements. These objects pose a burn hazard.
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