Natural fire

In some cases, however, a closer look at the actual course of the fire is necessary. This applies in particular to evacuation and smoke simulations. In addition, a closer look at the expected fire usually leads to a more economical assessment compared to the conservative ISO standard fire. An important example of this is steel frames for industrial halls. Important input parameters for the fire simulation are the fire loads and the ventilation in the respective building.

Every fire is different. Nevertheless, a characterization can be made through the different phases of a fire. In principle, a distinction can be made between developing and full fire. The figure below shows that there is a significant difference to the ISO standard fire, since this artificial fire room curve never subsides and comparatively high fire room temperatures prevail. It is therefore obvious that it is significantly more economical to verify a construction based on the actual fire loads (i.e. a natural fire) instead of using the ISO standard fire.

The development phase of a fire is characterized by relatively low fire room temperatures, since only a fraction of the existing fire load is ignited. However, after the initial ignition phase, there is a noticeable increase in temperature to around 50 to 100°C. This phase is called a smoldering fire. In the development phase of a fire, the behavior of the combustible building materials is decisive.

After a critical temperature has been exceeded, the developing fire develops into a full fire. This is initiated by the so-called flashover, since the temperatures in the fire room are so high that a large part of the existing fire load is now ignited and a large amount of thermal energy is released. However, the occurrence of the flashover is not inevitable. This characteristic point is missing especially with smaller fire loads. During the propagation phase, temperatures rise rapidly. Then the decay phase is initiated, during which the temperatures drop.

In the full fire phase, the behavior of the non-combustible building materials (e.g. the structural steel) is particularly important for the further course of the fire interest, since this determines the loss of load-bearing capacity and the spatial closure. A fire can be limited either by the existing fire load (fire load controlled) or by the oxygen supply (ventilation controlled).

Natural fire tests

The American "National Fire Reseach Laboratory" (NIST) provides data from very well-documented natural fires . In addition to the heat release rates, you can also find videos on natural fires, such as room fires, under the link.

How I can help you.

As expert in this field, I look forward to investigate suitable natural fire scenarios for your project. For the fire simulation we use so-called zone or field models, depending on the task. We can use the determined fire room temperatures for the fire design to increase the profitability of your project.

Non-binding initial consultation

The best thing to do is call me directly and tell me about your specific task. Or you can send me an email with your project data. Floor plans, views and sections of the respective construction project are helpful, which I will of course treat confidentially. If available, a fire protection concept is also helpful. On this basis we can discuss the general conditions and make you an attractive offer.