Coal and coal dust are widely used as a fuel in many different applications for generating heat or steam, like power plants, cement plants, steel plants, asphalt plants, …

To ensure the continuous supply of this fuel, it is stored in large silos, which can contain several hundreds or even thousands of m³.

Especially coal dust with its large surface and high catalytic reactivity can be (self) ignited easily.

So there are hundreds of thousands of coal silos in the world, that are all a potential risk of hazardous malfunction due to smouldering fire.

An undetected smouldering fire could lead to one of the following scenarios:

    Explosion of the silo: Especially during the filling of the silo with new coal dust using compressed air (!) an undetected smouldering fire could lead to an explosion of the complete silo.

    Flash of fire: If the incineration of the dust is not too fast, the increase of the pressure caused by the combustion will be released through explosion flaps at the top.

    Smouldering of complete coal: Even if the coal dust only smoulders until it is completely burned, without any hazardous risk, this would be an enormous but avoidable expense.

It is the operator’s duty to analyze possible combustion or explosion risks and to realize suitable preventive measures, such as:

  •     Avoiding of ignition sources
  •     Constructive explosion protection
  •     Permanent inertisation, with N٢, CO٢ or Ar
  •     Monitoring combined with fire extinguishing system

In many cases only a smouldering fire detection combined with an inertisation system is financially and safety-related suitable to protect against the hazardous malfunction.

The detection can be one of the following:

  • Temperature measurement
  • Laser gas analysis
  • Extractive gas analysis
  • InSitu gas analysis

The most important gas molecule to monitor for smouldering fire protection is CO. The measurement is mandatory for capacities of        > ١٢۰ m³.

The second one is O٢, as it indicates about the inert conditions in the silo, and is always related to CO, if a fire is present.

If O٢ and CO are measured simultaneously, smouldering fires can be detected and the efficiency of the inertisation is monitored.


As both gases are important to measure, the idea was to combine the plug&play, easy-to-use, no maintenance required

COMTEC ۶۰۰۰ O٢ / CO analyzer

with a clever designed housing, that meets the ATEX requirements, and offers long-term operation without any maintenance.

This was the birth of the



Field validation:

The system for the field validation was installed in ٢۰١۴-۰٢ in an asphalt plant and includes the following features:

    Simultaneous measurement of O٢ and COe

    Automatic blow-back, to ensure a continuous gas extraction

    Integrated compressed air conditioning, as instrument air is not available in such plants

    Automatic ١ point O٢/COe calibration, to supply always accurate measured values

The SILOTEC ٨۰۰۰ is field approved for smouldering fire protection in coal silos and offers the customer many benefits. It is…

  •     as a gas measurement representative for the complete process,
  •     compliant with the ATEX zone ٢۰,
  •     fast responding to even small changes of the gas matrix,
  •     Plug&Play, easy to install and does not require maintenance,
  •     highly reliable as O٢ and COe are measured simultaneously,
  •     an all-in-one design anddeveloped as a one-for-all solution.



(+9821) 22064015
(+9821) 22148186
(+9821) 22064015
(+9821) 22147985


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