Three Different Fire Suppression Approaches Used by Fire and Rescue Services

This paper describes the relationship between the water flow rate applied by the Fire and Rescue Services (FRS) and the area of a fire; the limitations of the FRS in terms of water flow rate; and the most effective use of firefighting water across a broad range of fire areas. The paper is based on five sets of data gained by the FRS at the fire scene, in total almost 6000 fires. It shows a fundamental difference in fighting a small fire compared to fighting a large one. It also shows that the relationship between applied water flow rate and fire area is not best described by a continuous power function. It distinguishes between three different approaches or modes of firefighting: a standard nozzle approach (fires up to 20–50 m², depending on context), a perimeter approach (fires up to 200–500 m², depending on context) and a maximum flow approach (fires larger than 200–500 m², depending on context). The transition between the approaches varies between the five data sets and can be distinguished using the optimum flow density (5.4–6.0 l/m² min) or the water flow density giving the smallest total volume and the critical water flow density (3.5–4.0 l/m² min). The two transitions vary with the context; they are not physical constants (the numbers corresponds to the most recent studies of Metro and County FRS). The study validates the strategic considerations that attack is more demanding than containment, that one should ensure containment and then attack; and that the earlier response, the better result.