Ratio pyrometers for industrial applications
20. Nov 2023
DIAS Infrared is expanding its range of ratio pyrometers. Based on Planck’s radiation law temperatures can be measured contactless using pyrometers. In the industrial environment in particular, there are applications where the emissivity of the measurement object is unknown or changes over time. Dust, absorbing gases or windows also lead to transmission losses between the measurement object and the pyrometer and are therefore sometimes critical.
Compared to the often used single-channel pyrometers, which work in a single wavelength range, so-called ratio pyrometers can help with these problems. They measure the infrared radiation emitted by the measurement object in two adjacent wavelength ranges. If the emissivities in both wavelength ranges are unknown or variable but identical (or almost identical), a temperature measurement that is almost independent of the emissivity is possible. The transmission losses mentioned are also irrelevant if they are the same in both wavelength ranges.
Ratio pyrometers are part of the PYROSPOT pyrometers from DIAS Infrared, which have proven themselves worldwide for many years. They are currently available in the stationary PYROSPOT series 10, 11, 44, 54, 55 and 56, some with fibre optics cable and optical head:
| PYROSPOT type | Temperature range | Spectral range | Fibre optics |
|---|---|---|---|
| DSR 10N | 500 °C to 3000 °C | 0,7 µm to 1,1 µm | |
| DGR 10N | 300 °C to 2300 °C | 1,5 µm to 1,9 µm | |
| DSRF 11N | 600 °C to 3000 °C | 0,7 µm to 1,1 µm | x |
| DGRF 11N | 300 °C to 2300 °C | 1,5 µm to 1,9 µm | x |
| DSR 44N | 600 °C to 2500 °C | 0,7 µm to 1,1 µm | |
| DSRF 44N | 700 °C to 1800 °C | 0,7 µm to 1,1 µm | x |
| DSR 54N | 500 °C to 3000 °C | 0,7 µm to 1,1 µm | |
| DSR 55N | 500 °C to 3000 °C | 0,7 µm to 1,1 µm | |
| DGR 55N | 300 °C to 2300 °C | 1,5 µm to 1,9 µm | |
| DSR 56N | 500 °C to 3000 °C | 0,7 µm to 1,1 µm |
The types “DSx” measure in two adjacent wavelength ranges in the spectral range between 0.7 µm and 1.1 µm and are suitable for high-temperature measurements at 500 °C to 3000 °C. The models “DGx” work in two wavelength ranges from 1.5 µm to 1.9 µm and can be used for lower temperatures (from 300 °C). The DGR 55N type, which is particularly robust for industrial applications, has now been newly introduced. All ratio pyrometers shown are, for example, well suited for temperature measurements on metallic surfaces.
In contrast to single-channel pyrometers, ratio pyrometers can also display the correct temperature when measuring objects with high temperatures compared to the environment are smaller than the measuring field. However, this requires optimized optical conditions in the ratio pyrometer. One example is the fibre optics device DSRF 44N, which enables temperature measurement even if the measuring field is only slightly filled (up to 10%).
The ratio pyrometers will be presented together with other PYROSPOT devices as well as PYROVIEW/PYROLINE thermal imaging cameras and PYROSENS infrared sensors from May 9, 2023 at the Sensor+Test (Nuremberg Exhibition Centre, Stand 1-244, Hall 1).
Further information:
- Overview of the PYROSPOT pyrometers
- More information and technical details about the pyrometers of the PYROSPOT series 55
- More information and technical details on the new ratio pyrometers PYROSPOT DGR 55N
Do you have questions? If necessary, contact our specialist for pyrometer solutions
Daniel Wagner
Application and sales, consulting: pyrometers and calibration sources
Phone: +49 351 896 74-13
E-mail: d.wagner@dias-infrared.de