The term extinguishing system also stands for fire-fighting or fire-extinguishing system and is a permanently operational technical system that contains a fire with an extinguishing agent. Stationary or fixed extinguishing systems often consist of a piping system with suitable extinguishing water discharge devices, e.g. sprinkler heads or extinguishing nozzles, which discharge the extinguishing agent when needed. In the event of a fire, this is done either indirectly or directly, i.e. either indirectly by fire detection systems or directly by fire detection and triggering elements such as glass drums or fusible links. The systems are designed to automatically control a fire until the fire department arrives to extinguish it. The colloquial term “extinguishing system” is therefore rather misleading. This is why the literature often uses the terms fire-fighting or fire-extinguishing system.

Extinguishing agents have the task of extinguishing flammable substances, taking into account their fire class and the prevailing environmental conditions (e.g. risk to persons or room size). Water extinguishing systems mainly use water alone, water with additives or extinguishing foam. Extinguishing foam is produced by adding air to water with foaming agent.