Infrared-Metrologie | Thermography
Thermography is an imaging method for displaying surface temperatures. The great advantage lies in the visual representation of temperature differences.
Thermographic measurements provide valuable contributions in the areas of:
- Prevention, damage prevention
- Environmental protection
- Operational safety
- Quality assurance
Only with the appropriate software can thermographic images be converted into a visually usable image (thermogram). With modern IR camera systems, thermography is a precise, fast and non-contact measuring principle over large distances.
Thermography offers great advantages for both qualitative and quantitative measurement tasks that cannot be performed with contact thermometers or pyrometers.
These are essentially measurement tasks
- at high temperatures, which do not allow the use of thermocouples
- on rotating, moving or inaccessible measuring objects
- on large surfaces, e.g. solar modules
- on live units or lines and contact points
- on surfaces with low thermal conductivity or objects / materials with low thermal capacity
Monitoring of thermal processes and manufacturing processes; casting, coating, rolling
Quality monitoring of melting and forming processes
Inspections of moving machine elements for friction and heat dissipation;
bearings, conveyor belts, turbines, motors (drives)
Insulation defects, defective (wet) insulation in piping systems / heat silos / heat storage tanks / district heating pipelines
Determination of heat distribution / cooling process in the production of roll / sheet material
In building thermography, the heat radiation emanating from a building is recorded and mapped on a thermogram in different temperature ranges. This makes it possible to assess the energy condition of a building (part of a building) to be examined and to identify weak points (e.g. thermal bridges, sealing and insulation faults) or other defects. In addition, the position or course of water pipes, heating pipes, underfloor heating pipes and the heat distribution in radiators can be mapped.
The evaluation of the thermograms can be used in particular to detect deviations in concealed components and thus to determine energy losses.
- Energetic assessment
Examination of weak points of insulation in existing buildings (heat losses), detection of thermal bridges and cracks, localization of framework under plaster
- Moisture damage
Moisture in building components, e.g. leaking flat roofs, damp masonry, localization of burst pipes
- Mold infestation
Mold growth is critically dependent on internal surface temperatures and relative humidity. The critical surface temperature for triggering mold formation at a room air temperature of 20 °C and 35 % relative room air humidity is about 7.3 °C. At a relative room air humidity of 70 %, the critical surface temperature must not fall below 17.9 °C. If the temperature falls below the critical surface temperature, the relative humidity of 80 % can be exceeded on the respective component surfaces, which can trigger mold growth.
- Landfills or tailings piles
Exothermic reactions due to chemical processes lead to heated local areas, which can be detected in the IR spectrum (heat pockets, smoldering fires).
- Contaminated sites
By heat radiation from the outside, it can be detected by different radiation ratios whether and which possible contaminated sites are hidden in a specified ground area.
- Water discharge
Dispersion from thermal processes (power plants) into flowing waters
Plumes of possible illegal discharge into water bodies
Thermograms can be used before mowing to detect and protect fawns.
Thermography in electrical installations
- Initial inspection of newly installed equipment (installation faults)
- Examinations at electrical low-voltage outdoor switchgears
- Inspections of overhead lines, inspections of installations in the direct and alternating current range
- Inspections of electrical installations (lines, switching devices)
- Detection of faults in solar modules
One of the basic quantities of the International System of Units is temperature. Along with pressure and concentration, it is the third of the so-called state variables, which clearly determines the energy content of a system. For each system, there is only one stable state, the lowest-energy state, for the defined state variables pressure, temperature and concentration. A system only leaves this stable state when the state variables change. If a body is in energy exchange with its environment, the temperature of the body and the environment changes until a new equilibrium is reached.
Basically, every surface, independent of the state of aggregation of the matter under consideration, emits an electromagnetic radiation, the so-called temperature radiation. This radiation propagates in free space as a transverse wave in a straight line at the speed of light. All radiations which form the electromagnetic spectrum differ only in the amplitude, the frequency and in their polarization state among themselves. Their intensity (amplitude) and wavelength depend exclusively on the temperature. The product of wavelength and frequency is always the speed of light.
Temperature radiation or thermal radiation thus arises from the internal energy state of a matter.
In the case of solids and liquids, the vibrations in the space lattice or the molecular bonds are essentially decisive for the intensity of the radiation. In gases, the energy state is determined by the rotation, oscillations and velocity energy of the individual atoms or molecules.
The intensity of thermal radiation from solids as well as liquids exhibits a uniform spectrum of wavelengths that extends continuously from the visible to the far infrared range. Whereas gases exhibit radiation only in certain narrow wavelength ranges.