User Manual

Siemens Switzerland Ltd 15
Building Technologies Division
2. Fire detection
The earlier a fire is detected, the more time there is for evacuation and extinguishing, and the less damage can
occur. Earliest possible detection is thus the key to minimizing damage and gaining precious intervention time.
2.1. Fire basics
To ensure reliable, early detection of fire, it is important to be familiar with the different fire phenomena, fire
propagation and possible deceptive phenomena.
2.1.1. Fire phenomena
Fire phenomena are physical values that are subject to measurable change in the development of a fire (e.g.
smoke, heat, radiation, gas).
Large volumes of volatile fire aerosols are produced with almost all hostile fires. Smoke has thus become the most
important fire phenomenon for the early detection of fire.
Liquid fires directly develop flames which immediately create a temperature increase and heat radiation.
2.1.2. Fire propagation
The fire phenomena generated by fire propagate differently, depending on the room size and the room conditions
such as a high air circulation. This must be taken into account when planning a fire detection system.
Figure 2.1.2-1 Propagation characteristics of fire phenomena