NEW compact two-colour pyrometer with integrated display and keyboard

With a parallax-free laser aiming option | World Firsts!

CellaTemp compact pyrometer
CellaTemp compact pyrometer

Ibbenbüren-Laggenbeck, Germany — The new two-colour pyrometer of the CellaTemp PK series are equipped with a contamination detection function (CDF).

A very strong contamination of the inspection glass or the lens of the pyrometer or a high concentration of dust and vapour in the viewpath towards the object to be measured trigger an alarm signal. This ensures a high operating reliability.

In addition, it saves costs as regular maintenance and visual control by the service personnel is no longer needed.

The two-colour pyrometer offers the option to evaluate the spectral temperatures as well.

Practically, the new two-colour pyrometer of the CellaTemp PK series can work as a “double pyrometer”, i.e. as a two-colour pyrometer or a spectral pyrometer.

This feature enables interesting opportunities for signal evaluation, such as an analysis of the radiation properties of the target object.

As three temperature values have to be detected and evaluated, the hardware and computational complexity of a two-colour pyrometer is significantly higher than that of a single channel pyrometer.

Keller therefore reached limits to further miniaturise the two-colour pyrometers.

With the pyrometer series CellaTemp PK, however, Keller switched the electronic system to novel high performance processors and achieved a miniaturisation of the components at the same time.

Complex converters and IO components have new functionalities which alone made it possible to integrate a two-colour pyrometer in such a compact housing design.

This design with a M30 central thread is very common on the sensor market as it offers very easy installation options.

In addition to the measured temperature, the device displays warnings and error reports, e.g. for incorrect connections or inadmissible operating conditions.

Extensive configuration options and functions can be keyed in on the device itself. Very useful for the instrument setup is the service function.

A temperature value or a current signal can be simulated to check a correct operation and scaling of the pyrometer and the configuration of downstream devices connected via analogue output or switching output without needing a hot target object.

In service mode, the signal intensity is displayed and the device is adjusted to the maximum value to check the ideal adjustment of the pyrometer to a hot target.

The new two-colour pyrometer of the CellaTemp PK series can be supplied with or without integrated LED spot light. The special feature of the patented spot light is that it shows both the exact position and the true size of the measuring point.

Low-cost pyrometers with laser sighting are affected by parallax, i.e. the laser and the target area are not on the same axis but they are displaced in parallel. With simple instruments, the laser spot is merely an approximate orientation guide and it does not show the true size of the measuring point.

The LED spot light, which is uncritical from a safety point of view, lights up permanently and thus offers a high degree of operational safety.

The very limited life span of laser spot lights does not apply to LEDs. Moreover, the laser intensity decreases rapidly with increasing ambient temperatures and is limited to 50°C ambient temperature.

All models of the CellaTemp PK series can be used without cooling up to a temperature of 65 °C.

The spot light version is available for a focal distance of 200 mm and 1000 mm.

The version without a spot light uses a focal distance of 1500 mm.

The measurement range extends from 550 °C (600 °C for the spot light version) to 1600 °C.

In addition to its analogue output, the CellaTemp PK has two switching outputs that provide a wide variety of configurations and combinations. For example, in an inductive billet heating process, the pyrometer offers the option to directly discard too cold and too hot billets separately from each other.

The pyrometer can be connected with a standardised cable with M12 plug.

The CellaTemp PK series is complemented by a very extensive range of accessories, such as holding device, axial air nozzle, cooling jacket, protective glass, insulating flange, dust stop, ball flange and various mounting assemblies to allow for safe operation in the wide range of applications

About Two-Colour Pyrometers

Modern two-colour pyrometers detect the thermal infrared radiation to determine the temperature not only at one wavelength, as with a conventional spectral pyrometer, but at two wavelengths at the same time and place.

A quotient is then calculated from the two measured radiation intensities. This value is proportional to the temperature.

The specialty and the big advantage of a two-colour pyrometer is that the temperature value remains at a constant level, even when the infrared radiation emitted from the target is reduced, for example, by dust, vapour or dirty protective glasses.

The temperature is still measured correctly even with a very low signal strength (90 % reduction).

Therefore, two-colour pyrometers are preferably used for industrial applications in extreme ambient environments and under adverse measuring conditions, such as rotating kilns in the cement industry, rolling mills in the steel industry or foundries to measure liquid metals.

A variation of the radiation properties of the target object, i.e of the emissivity coefficient, does not have a negative influence on the temperature measured, if the variation remains neutral regarding the wavelengths.

Another advantage is that the target object may be of a smaller size than the target marker in the pyrometer’s viewpath. This makes a two-colour pyrometer less sensitive to target adjustment inaccuracies when measuring small targets, such as spots in inductive heating systems.

Another application where a two-colour pyrometer delivers more stable readings is the temperature measurement of glass drops or of glass poured into a mould. The pyrometer’s measuring principle prevents the measuring signal from being affected by the type of glass and its colour or the diameter of the glass drop, whereas changing production factors may produce wrong temperature values when measuring with a single channel/spectral pyrometer.

More details online at

About Keller

For more than 40 years now, the MSR Division of KELLER has been designing and manufacturing instrumentation for process control applications. Keller MSR is both a maker of measuring equipment as well as a provider of automation engineering solutions. We have been helping a wide range of industries to monitor, control, and manage their process parameters. Keller MSR’s products and customized services include temperature measuring instruments, moisture detection devices, temperature data loggers, and dedicated software. In addition we offer innovative automation solutions and control systems for input logistics, weighing/mixing/dosing processes and bulk material transport.

Carl-Keller-Strasse 2-10
D-49479 Ibbenbüren-Laggenbeck

Phone: +49 (5451) / 85-0
Telefax: +49 (5451) / 89 73 92