Further practical tips Infrared measuring instruments

Natural objects in open air such as water, stone, earth, sand, plants, wood, etc. have emission levels between 0.8 and 0.95 in the spectral range 8 and 14 µm. If measurement is to be performed in the open air, it may be necessary to take “cold sky radiation” into account in the case of small emission levels. Wherever possible, however, this “ambient radiation” should lie in the proximity of the air temperature. This is achieved by screening the interfering radiation, e.g. with a box or an umbrella over the measuring point.
-> Measurable with Testo IR measuring instruments Glass and quartz Have high emission levels of approx. 0.90 in the wavelength range over 8 µm. Non-transmissive to IR, i.e. the glass pane is measured.

-> Measurable with Testo IR measuring instruments Plastics Are measured in the temperature range between +20 °C and +300 °C during drying and forming processes, extrusion, calendering, deep-drawing, etc. The emission level of almost all plastics is between 0.8 and 0.95, and is therefore easy to measure.
-> Measurable with Testo IR measuring instruments Transparent films Have, at certain wavelengths, a characteristic absorption band, which means that the emission level is, however, dependent on the thickness of the film. The thinner the film, the lower the emission level. Thin films are often transmissive in the IR range. Take the background into account.

-> Conditionally measurable with Testo IR measuring instruments Hot gases and flames Are “volumetric radiators with selective emission characteristics”. The measuring point is no longer planar. The average temperature value is taken from a section inside the flame. This value is also frequently influenced by furnace walls behind the flame or gases. As with transparent materials, flames and gases radiate primarily in certain spectral ranges, for example in the range around 4.3 µm (CO2 band).
-> Measurable with special instruments -> No measurable with Testo IR measuring instruments