The fire disaster
Among the different types of losses that can be encountered, fire is probably one of the most devastating, as well as one of the most difficult to understand; the fire transforms or even destroys its environment as well as potential elements of proof.
However, in order to establish a claim or to find the responsibility of a party, it is necessary to determine the exact circumstances of the disaster.
For this, it is essential to know how to observe, analyze and interpret the traces left by the combustion.
In order to do so, the surveyor in the research of the causes and circumstances of the fire (RCCI) must master the basic principles of combustion, the development of the fire, as well as the heat transfers generated by the fire.
What is combustion ?
Combustion is a redox chemical reaction in which the oxidant is called the oxidizer and the reductant is called the fuel.
To complete the reaction, it is essential that an activation energy is reported.
This triptych is often referred to as the triangle of fire.
A story of proportion :
However, it is important to specify that the presence of these 3 elements is not enough to initiate combustion.
Indeed, the proportions of fuel and oxidizer present are essential to ignition, this critical concentration is delimited between the LFL (Lower Flammable Limit) and the UFL (Upper Flammable Limit).
Outside this range, no ignition will be possible.
Some examples :
The reasons for its propagation :
Assuming that sufficient energy would be put in the presence of the right proportions of oxidizer and fuel, a flame would be obtained.
But how do we explain the propagation of fires and in essence their destructive force?
The answer lies in the transmission of heat. The fire benefits from 3 modes of heat transfer allowing its development.
- Conduction which consists in the transfer of heat inside the materials ;
- Convection which consists in the transfer of heat and matter ;
- The radiation which consists in the transfer of heat without transfer of matter ;
This heat transfer then plays the role of activation energy on the various bodies encountered while the oxygen naturally present in the air plays the role of oxidizer, thus allowing the fire to spread far and wide.
The knowledge of the mechanics of fire at the service of the RCCI expert :
The fire in its progression leaves specific traces, which, combined with a thorough knowledge of its mechanics, will allow to trace the path of the fire to its initial place of ignition.
In this sense, the RCCI expert’s method remains unchanged.
By their observations, they will retrace the path of the fire back to the place of ignition, which may be more or less extensive depending on the level of destruction and the violence of the disaster.
Thus, the damage arrangement allows to locate the module of the start of the fire (above) or the filling level of the tank after the fire by the soot deposit (below).
Once in this area, the expert will try to find the probable causes of the fire based on the above-mentioned triptych.
In order to do so, it may be necessary to take samples, perform chromatographic analyses in the laboratory, or even perform 3D reconstructions, a subject that we develop in this special report.
CRTL and RCCI :
The regular confrontation with this type of disaster has pushed us to train ourselves in order to guarantee a high level of understanding of the phenomenon, and thus to respond as well as possible to the various requests of our clients.
We are therefore delighted to announce that we now have 2 RCCI experts trained by the CNPP, and we are at your disposal for any request.
