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    Adjust emissivity

    Thermography: knowledge and practice

    The correct setting of the emissivity is particularly important when there are large temperature differences between the measurement object and the measurement environment.

    • If the temperature of the measurement object is above the ambient temperature:

    • If the emissivity is set too high, the temperature readings in the thermal image will be too low.

    • Emissivities set too low in the thermal image result in temperature readings that are too high.

    • If the temperature of the measurement object is below the ambient temperature:

    • If the emissivity is set too high, the temperature in the thermal image will be too high.

    • Emissivities set too low in the thermal image result in temperature readings that are too low.

    Emissivity tips

    • The greater the difference between the temperature of the measurement object and the ambient temperature and the smaller the emissivity, the greater the measurement errors. These errors increase if the emissivity is set incorrectly.

    • Many materials that are transparent to the human eye, such as: B. glass, are not permeable to long-wave infrared radiation.

    • The few transmissive materials include: B. thin plastic films and germanium, the material from which the lens and the protective glass of a Testo thermal imaging camera are made.

    • If necessary, remove any covers on the measurement object, otherwise the thermal imaging camera will only measure the surface temperature of the cover.

    • Always observe the operating instructions for the measurement object.

    • If elements that lie beneath the surface influence the temperature distribution on the surface of the measurement object through heat conduction, structures of the internal structure of the measurement object can often be seen on the thermal image. Nevertheless, the thermal imaging camera only ever measures the surface temperature. An exact statement about the temperature values of elements within the measurement object is not possible.

    Thermography in practice

    Find out in our compact tutorial how theoretical basics and the right thermal imaging camera can be used to create meaningful thermal images in practice.

    Thermography: In practice