Particle Size

Why Small is Beautiful

Common to all Concept standard smoke generators is our incorporation of precision machined, specially treated steel heat exchanger blocks, in which the smoke fluid is vaporised.

What sets us apart?

At the heart of all Concept mains powered smoke generators is a heat exchanger block which is machined to tolerances that are measured in microns. This approach results in a consistency of smoke quality and smoke particle size that is unmatched by other manufacturers.

That may seem academic, but if you take the adjacent picture as an example, if the particle on the right was a 0.2 micron Concept particle, the one on the left would be just over 1.5 micron diameter. That’s fairly typical of our competition, who generally produce fog particles 1 – 5 micron diameter using cast or platen type heat exchangers.

This compares with a typical particle size of just 0.2- 0.3 micron mmd for the vast majority of our smoke systems, be they water or oil based.

The general benefits of producing such a consistent and clearly defined particle distribution are:

  • the smaller the particle size of the smoke, (or more accurately fog) the smaller the amount of chemical is required within the atmosphere to achieve any given visibility. This can have a significant effect on running costs for heavy users of artificial smoke (fire brigades etc.)
  • the less the amount of chemical in the atmosphere, the safer the smoke if measured in terms of relative Occupational Exposure Levels.
  • the smaller the particle size of the smoke, the lower its settling velocity (the rate at which a particle will fall, due to gravity). A smoke particle of unit density, 0.2 micron in diameter, will fall at 8mm /hr, compared to a 2 micron particle, which falls at 468mm/hr. In essence this means that the smaller the particle of smoke you produce, the less chance there is that deposition of smoke particles will occur.
view of sectioned block
particle size comparison
thermal generator

Concept's expertise in our field means that we actually produce systems specifically designed to fulfil the requirements of BS 5295/EN-ISO 14644-3 Section C.6.3, for the testing of HEPA filters in the nuclear, chemical and pharmaceutical industries Concept also have personnel registered with the National Radiological Protection Board (NRPB) for site work at nuclear establishments.

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East Sussex County Council

"I was very impressed with the smoke generators provided by Concept Engineering and feel they could be confidently recommended at our group meetings to other tunnel operators who may be contemplating an emergency exercise.

The reaction of the tunnel environmental control system visibility sensors to the smoke was excellent, not only did the fans cut in but the volume of smoke was such that it immediately tripped a high level alarm which additionally sends a signal in the form of a general alarm to the Sussex Police Headquarters.  Had the smoke been generated by a real incident the alarm would have alerted the Police to the problem in the tunnel probably before a call was made from a tunnel emergency phone." 

After Operation Orpheus - Dartford Tunnel