PYROPHOT

Pyro PhotoPYROPHOTTM is an Ultraviolet pyrometer with unrivaled accuracy. It is highly sensitive to temperature variations and has a very low sensitivity to variations of emissivity and temperature of environment.

Key Features :

  • From 650 ° C
  • Sensitivity: 0.1 ° C
  • No emissivity setting
  • Suitable for industrial environments
  • Integration time ≥ 1 ms
  • UV pyrometry measurement
  • 100% digital chain
  • Modular Software

 
 
 
 
 
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Other main advantages of PYROPHOT are:

Exceptional temperature sensitivity:  1% temperature increase results in more than 35% increase of signal measured
Wide measurement range: process works from 650°C up to as much as 3000°C and far beyond
Possible measurements on durations from 1 µs up to several minutes depending on the process to be controlled
Easy handling: no need to preset emissivity value or re-calibrate equipment
By using photon counting, the most efficient process for electromagnetic signal detection, PYROPHOT provides the advantages of fully digital signal treatment equipment, and particularly, offers exceptionally consistent performance.
For all materials, PYROPHOT will not only deliver at least 2.5 times more precise absolute temperature results than conventional pyrometers but also its sensitivity to ambient disturbances will be 2.5 times better.

The table below shows a comparison of measurement results given by a PYROPHOT and those by a conventional IR pyrometer. Both aim at a metallic body heated up to 700°C and the supposed emissivity value (preset on the pyrometer) is 0.5. Values displayed correspond to the results obtained when the true emissivity differs from 0.5.

 

True emissivity
0,25 0,5 0,75
PYROPHOT
0,37µm
717°C 700°C 690°C
IR Pyrometer
1µm
748°C 700°C 674°C

PYROPHOT delivers results with a better than 3% precision for emissivity variations up to 50%.

Reliable, robust, insensitive to emissivity and with excellent precision. Our PYROPHOT is ideal for :

  • Integration on a production line
  • R & D
  • Custom Applications

 

Metallurgy : Integration on a production line, control or chain automation, energy optimization. Thanks to its low sensitivity to emissivity, PYROPHOT allows precise control of temperature, essential in lines using recycled materials that present varying thermo-optical properties.
Glass factories: energy optimization, production line control, automation, security, …
Nuclear : security, control, research, …
Research: emissivity, materials studies,…

More generally, any application that requires an accurate measurement of temperatures above 650 ° C.

Custom : our team of research engineers is at your disposal to develop, according to your specifications, an equipment adapted to your requirements.

Please, feel free to contact us for any enquiry

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Return to basics

To measure a surface temperature we use the radiation flux of thermic origin that all bodies emit. The physical law that governs this phenomenon is Planck’s Law that describes the behavior of an ideal entity called the blackbody. The set of curves in Figure 1 describes the spectral distribution of this radiation for several temperatures representative of those commonly encountered, particularly in metallurgy.

 

 

 

We see that the peaks of these curves are located in the infrared (λ>0,8µm) and that the hotter the body is, the more the curve shifts toward short wavelengths.
All equipment currently marketed work in the infrared, meaning close to energy peak, which allows reducing the cost of their fabrication.

 

Emissivity gets in the way

 

Unfortunately the blackbody is a purely theoretical entity for, in nature, no body is perfectly black or even grey. Planck’s Law gives only the maximum radiant energy that a body can emit. This value must be weighed by an inclusive factor between 0 and 1 called emissivity and symbolized by the Greek letter ε. To complicate everything, this factor which depends on the nature of the body to be measured, varies according to the condition of the surface (oxidized or not), the wavelength and even the temperature! If controlling an industrial process is desired in following the evolution of the heating of a body, a constant and precise temperature measurement is necessary. However, as we have seen, the result obtained by measuring the flux depends also upon the variation in emissivity. Up to now, there has been no reliable and exhaustive experimental data available that would allow an analytical representation of this factor, or even a reliable interpolation with all the parameters concerned. In the low-cost equipment that can be found on today’s market there is a pre- defined emissivity value, usually 0.8. On the more sophisticated equipment the user chooses an emissivity value that remains unchanged until the end of the running process. As a direct consequence, the measurement result is false and the estimation of the error value is very unpredictable since we have no idea of the amplitude of variation of ε !

 

Signal variation 100 times greater in ultraviolet

Ultraviolet pyrometry and its generalization, ultraviolet thermography, bring the solution because the measurement is done in a spectrum range where the signal variation with temperature is so large that it hides the consequences of an emissivity variation. Due to the linear scale used in Figure 1, there is no evidence of the steep slope of the curves on the left of the energy peak. In Figure 2, with a logarithmic scale, we zoom toward the short wavelengths for the two temperatures 800°C and 1000°C.

 

 

It can be seen that at 0.3µm, in the UV, a 200°C variation results in a multiplication by 1000 of the energy signal, whereas it is only multiplied by 10 at 1µm. The drawback is that the energy levels in the UV are 10-10 times lower.

A reliable solution, highly sensitive and sturdy

Photomultipliers are detectors that have been designed to deal with these extremely weak energy levels. We use photomultipliers in the photon counting mode whose intrinsic noise is only 10 photoelectrons/second and a 100 photoelectron/second signal (that is to say 10-16 joules) is good enough to get a significant measurement result. Due to the extreme sensitivity of our detectors we can work with a very narrow bandwidth, almost monochromatically. Since the signal doubles every 20°C, we obtain very precise results.  Another advantage of such a measurement process is that it is fully digital, from the captor to the display of the result. Thus we get rid of the drift problem that is the main flaw with analog devices and we get an excellent repeatability of results. Moreover, these photon counting devices have proven to be very sturdy and they can work continuously in a harsh environment for years.

Return to basics

To measure a surface temperature we use the radiation flux of thermic origin that all bodies emit. The physical law that governs this phenomenon is Planck’s Law that describes the behavior of an ideal entity called the blackbody. The set of curves in Figure 1 describes the spectral distribution of this radiation for several temperatures representative of those commonly encountered, particularly in metallurgy.

 

 

 

We see that the peaks of these curves are located in the infrared (λ>0,8µm) and that the hotter the body is, the more the curve shifts toward short wavelengths.
All equipment currently marketed work in the infrared, meaning close to energy peak, which allows reducing the cost of their fabrication.

 

Emissivity gets in the way

 

Unfortunately the blackbody is a purely theoretical entity for, in nature, no body is perfectly black or even grey. Planck’s Law gives only the maximum radiant energy that a body can emit. This value must be weighed by an inclusive factor between 0 and 1 called emissivity and symbolized by the Greek letter ε. To complicate everything, this factor which depends on the nature of the body to be measured, varies according to the condition of the surface (oxidized or not), the wavelength and even the temperature! If controlling an industrial process is desired in following the evolution of the heating of a body, a constant and precise temperature measurement is necessary. However, as we have seen, the result obtained by measuring the flux depends also upon the variation in emissivity. Up to now, there has been no reliable and exhaustive experimental data available that would allow an analytical representation of this factor, or even a reliable interpolation with all the parameters concerned. In the low-cost equipment that can be found on today’s market there is a pre- defined emissivity value, usually 0.8. On the more sophisticated equipment the user chooses an emissivity value that remains unchanged until the end of the running process. As a direct consequence, the measurement result is false and the estimation of the error value is very unpredictable since we have no idea of the amplitude of variation of ε !

 

Signal variation 100 times greater in ultraviolet

Ultraviolet pyrometry and its generalization, ultraviolet thermography, bring the solution because the measurement is done in a spectrum range where the signal variation with temperature is so large that it hides the consequences of an emissivity variation. Due to the linear scale used in Figure 1, there is no evidence of the steep slope of the curves on the left of the energy peak. In Figure 2, with a logarithmic scale, we zoom toward the short wavelengths for the two temperatures 800°C and 1000°C.

 

 

It can be seen that at 0.3µm, in the UV, a 200°C variation results in a multiplication by 1000 of the energy signal, whereas it is only multiplied by 10 at 1µm. The drawback is that the energy levels in the UV are 10-10 times lower.

A reliable solution, highly sensitive and sturdy

Photomultipliers are detectors that have been designed to deal with these extremely weak energy levels. We use photomultipliers in the photon counting mode whose intrinsic noise is only 10 photoelectrons/second and a 100 photoelectron/second signal (that is to say 10-16 joules) is good enough to get a significant measurement result. Due to the extreme sensitivity of our detectors we can work with a very narrow bandwidth, almost monochromatically. Since the signal doubles every 20°C, we obtain very precise results. Another advantage of such a measurement process is that it is fully digital, from the captor to the display of the result. Thus we get rid of the drift problem that is the main flaw with analog devices and we get an excellent repeatability of results. Moreover, these photon counting devices have proven to be very sturdy and they can work continuously in a harsh environment for years.

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