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Flame Scanners

The new solution for monitoring combustion processes of any kind is based on sensing and evaluating the difference of flame temperature and variation of the same at two predetermined points. The patented method is making use of the fact that combustion is maintained only when there is always sufficient energy fed back into the ignition zone in order to maintain combustion. Because of this, the recirculation of the combustion gases in the flame mantle is monitored by flame scanner. The result is a detection method which works reliably fully independent of fuel with any flame colour.

The world-wide application, mainly in the petrochemical industry demonstrates that this principle permits flame monitoring systems far superior to conventional optical systems used so far. As radiation sensors two thermoelement chains are used, vapour-deposited on a substrate, because these have linear sensitivity across the complete radiation emitted by the flames and therefore can be made selective for defined wave length ranges by filters. An optical system defines the two cones of view and preallocates temporarily the wave length range. Additional filters can further reduce the flame spectrum to be evaluated in order to pick up only the spectral lines of typical combustion products like, for inst., CO, CO2, H2S or H2O. In this way applicationoriented flame evaluation can be effected.

The flame scanner is directed towards the combustion so that the two thermoelement chains recognise along the flame points offset to each other. The scanners are inter-connected antiparallel and, therefore, produce at the output the difference of the radiation power picked up. As the two measuring points in the flame are positioned close to each other the same emissivity applies to both allowing determining the temperature difference.

The downstream amplifier cuts off variations with low frequency and processes flame signals only between 25Hz and 1000Hz, in order to concentrate on temperature movement. Faulty signal emission from the glowing brick lining is excluded because their absolute radiation is being shielded due to the antiparallel connection of the thermoelement chains. Possible low-frequency modulation by stack gases is picked up by both elements and does not produce a difference signal of higher frequency which could be evaluated.


  • Fail-Safe, Self-monitoring, fully electronic design
  • Built in amplifier
  • Approved for continuous operation and intermittent operation
  • TÜV approved (DVGW / CE)
  • Approval according to EN298: 2012-11
  • SIL3 approved
  • Connection Compatible with all other BFI flame sensors
  • Spectral range 300-2700 nm
  • Sensitivity for each sensor range adjustable
  • Robust aluminum housing in protection class IP 65
  • Also available in fibre-optic technology
  • ATEX Zone 2 as standard, optionally ATEX Zone 1