Protection of workers in combating incipient fires (SUVE)

Project No. FF-FP 0405


completed 03/2022


In order to improve the protection of workers in combating incipient fires, the definition of incipient fire needs to be revised. For this purpose, the definition contained in workplace rules (ASR) A2.2 must be linked with comprehensible thresholds. These can be compared with thresholds for radiation intensities, visual impairments and fire smoke toxicities. This comparison forms the basis for assessing up to which stage of a fire a safe firefighting by unprotected workers is possible.

Small extinguishing devices such as "fire extinguishing sprays" as well as classic fire extinguishers and their advantages and disadvantages were considered.


Relevant scenarios for extinguishing incipient fires by the use of portable fire extinguishers were derived from case studies. These scenarios were simulated by using computer-aided numerical methods. For these simulations, the existing normative concept of test fires and typical furnishings of workplaces were characterized with fire technology standards. Furthermore, the required extinguishing agent quantities and types were determined. The suitability of the existing concept for test fires was examined. The simulations carried out on these bases were used to assess the extinguishing of incipient fires and to derive possible improvements for the protection of the workers.


The test fire 8A contained in DIN EN 3-7 is suitable for characterizing the extinguishing capacity of portable fire extinguishers, but that the use of this test fire for describing an incipient fire in a working environment comparable to an office is not expedient. For example, during the experimental execution of this test fire in an office-like environment, fire-induced temperatures occur that do not allow safe firefighting either with fire extinguishers classified for this purpose or with fire extinguishing sprays.

For the description of an incipient fire in an environment comparable to an office use, further tests were carried out with wooden cribs based on the wooden crib described in UL 1715. It was found that even with these significantly smaller wooden cribs, it is not possible to safely extinguish an incipient fire because the carbon monoxide concentrations recorded during the extinguishing tests do not allow such an assessment. Rather, even for these wooden crib fires, only low-hazard firefighting can be assumed.

The consideration of the basic suitability of fire extinguishing sprays for incipient firefighting showed that they are very well suited for firefighting of fires on the scale of Advent wreaths and paper baskets, especially due to the ease of use and handling, while suitability for incipient fires to be associated with a wooden crib fire following UL 1715 is no longer present under the selected test conditions.

For the equipment of workplaces with fire extinguishing devices - and the associated ASR A2.2 - this means that a provision of fire extinguishing sprays, due to the time advantages in the intervention time, is recommended and should be combined with the provision of fire extinguishers with a greater extinguishing capacity. Thus, with the help of fire extinguishers with a greater extinguishing capacity, fire-fighting measures can also be carried out in the case of advanced incipient fires, where fire extinguishing sprays are no longer useful. It should be noted, however, that in premises comparable to those of an office use, a safe approach to the fire is no longer possible even with fire extinguishers due to the fire smoke. The limits of use of both the fire extinguishing sprays and the fire extinguishers must be explained by the company during the training to be carried out to improve the protection of the insured persons when fighting incipient fires.

Last Update:

11 Jul 2023


Financed by:
  • Deutsche Gesetzliche Unfallversicherung e. V. (DGUV)
Research institution(s):
  • Universität Wuppertal

-cross sectoral-

Type of hazard:

work organization/safety and health management


prevention, fire and explosion protection, qualification, education, didactics etc.

Description, key words:

incipient fires, fire combating