After the fire catastrophes in the Mont Blanc, Tauern and Gotthard road tunnels, new guidelines for improvement of the tunnel safety have been developed, such as the German RABT 2006 or the Swiss ASTRA directive
Drawback of existing visibility monitors is that they are too accurate and thus too expensive for the application as smoke/fire detector. This problem is now solved by SIGRIST with the new smoke detector FireGuard. The FireGuard is using scattered light however avoiding any moveable components. The simple and compact design simplifies maintenance, an annual check using the checking rod and cleaning of the flow cell is sufficient. Tests could demonstrate that the values in case of fires are very comparable with existing measurements and that the instrument reacts within seconds. A built in temperature probe helps to localize fires if larger areas are filled with smoke. An optional heater on the sampling inlet reliably eliminates effects of fog and mist, signal outputs are realized via relay contacts or a Profibus interface. The convincing features and its performance recently lead to the installation of the FireGuard in the Gotthard road tunnel.