Presentation; Functioning - Emissivity - Chauvin Arnoux C.A 1864 Notice De Fonctionnement

English C.A 1864 – C.A 1866
1.

PRESENTATION

The C.A 1864 and C.A 1866 infrared thermometers are for the remote
measurement of the temperature of most materials without physical contact, with
an emissivity coefficient situated between 0.1 and 1.
They can also measure the temperature of polished metal surfaces after treatment
(marking with opaque labels or mat spray paint) to limit the "mirror" reflexion effect
of stray infrared ray interference. This treatment brings the emissivity coefficient to
above 0.1 which ensures correct measurement. An emissivity table gives the
emissivity ranges of a wide range of materials.
To measure a body's temperature, simply point the probe at its surface. The
temperature displayed on the digital screen depends on the measurement
parameter selected and on the emissivity chosen (according to material). The
thermometer automatically switches off after 10 seconds.
2.

FUNCTIONING - EMISSIVITY

All objects above absolute zero (-273.15°C) give out infrared energy. This radiated
energy is emitted in all directions at the speed of light.
The instrument's lens picks up this energy and focuses it on an infrared detector.
This detector gives a voltage signal proportional to the quantity of energy received
and hence proportional to the temperature of the object.
Some objects not only give out infrared energy, but also reflect it as well. Unlike
matt surfaces, brilliant or highly polished surfaces tend to reflect energy. This
possible reflection is represented by a factor known as the emissivity, and can vary
between 0.1 for a highly reflective surface, and 1 for a black body.
In the case of the C.A 1864 and C.A 1866 thermometers, the emissivity can be
adjusted from 0.1 to 1, the value of which is determined depending on the material
of the body or surface to be measured.
These thermometers are suited to measurements on varnished, anodised or
oxidised surfaces, but taking into account their spectrum, shorter wavelength
instruments are better adapted to measurements of brilliant surfaces. (see §
Emissivity table).
To have a precise measurement, keep your thermometer perpendicularly to the
target.
Page 20