Procedure in which the measurement values of an instrument (actual values) and the measurement values of a reference instrument (nominal values) are determined and compared. The result provides clues as to whether the actual measuring values of the instrument are still within a permissible limit/tolerance range. In contrast to an adjustment, the identified deviation from the actual measuring value is merely documented in a calibration and not adjusted to the nominal measuring value. The intervals at which a calibration is to be performed depends on the respective measuring tasks and requirements.
Temperature unit. Under normal pressure, the zero point of the Celsius scale (0 °C) is the freezing temperature of water. A further fixed point for the Celsius scale is the boiling point of water at 100 °C.
°C = (°F - 32) / 1.8 or °C = K - 273.15.
Coldspot and hotspot
The coldest spot of an area on the thermal image is referred to as a “coldspot”, and the hottest spot is referred to as a “hotspot”.
Using the function “Auto Hot/Cold Spot Recognition”, you can display these two spots directly on your thermal image in the imager display. This function is also available in many of the analysing software packages. e.g. Testo IRSoft. In this software you can also display these two spots for any areas of the thermal image you wish to define.
Coloured body radiator
Coloured body radiators are materials whose degree of emissivity is dependent on the wavelength. If one views the same object with a thermal imager in the long-wave infrared range (LIWR, 8 – 14 μm), and one in the medium-wave infrared range (MIWR, 3 – 5 μm), it can be necessary to set different emissivities in the thermal imager.
Selection of colours for the thermal image in the imager (e.g. colour palette “rainbow”, “iron”, “grey scale”). The contrasts of the thermal images can be shown with varying quality depending on the measuring task and the colour palette set. The colour palette can also be set individually using analysing software (e.g. Testo IRSoft) after the thermal image has been saved. Pay heed to the interpretability of your thermal image when choosing the colour palette. Red and yellow colours are intuitively associated by the viewer with heat, green and blue colours with cold.
Transition of a substance from gaseous to liquid state. Air humidity can condense on surfaces if the surface temperature, and therefore the temperature of the air on the surface, is lower than the dew point temperature.
Heat conduction. Transfer of thermal energy between neighbouring particles. Here, energy is always transferred from the warmer to the colder particle. Unlike convection, there is no mass transport of particles in conduction.
Heat transfer, whereby thermal energy moves from one fluid or gas to another as a result of the mass transport of particles.