Fire Gas Detection
Fires produce gases whose composition allows conclusions to be drawn about the type of fire and the material. It also shows whether there is actually a fire. Smoldering fires release smoke (aerosols) and various gases. In addition to carbon dioxide (CO2) and water (H2O), these include the characteristic smoldering gases carbon monoxide (CO), hydrogen (H2) and a broad cocktail of various hydrocarbons. Depending on the material, HCl, H2S, HCN, NOX and other components are also produced. GTE Industrieelektronik GmbH offers a detector for this purpose, which responds to the gases carbon monoxide (CO), hydrogen (H2), phenolic hydrocarbons (HC) and qualitatively to nitrogen oxides (NOX) with the aid of four different gas sensors. The detection sensitivity is in the range of a few ppm.
The lifetime of semiconductor gas sensors is much longer than that of many other sensors (e.g. amperometric or electrochemical sensors). A semiconductor layer is deposited on a heated carrier substrate. The sensor signal is obtained from the electrical conductance of this layer. Depending on the gas to be detected, the optimum operating temperature can be up to 450 °C.
Robust Design for Industrial Environments
The fire gas detector GSME and its sensors are integrated in a die-cast aluminum housing; the gases diffuse through a sintered metal filter to the sensor elements. A robust and dust-tight design is thus achieved. A type-tested housing variant is available for areas that are at risk from dust explosions. The detectors are robust and also available in variants for use in potentially explosive atmospheres.
Under particularly adverse environmental conditions, such as in dusty environments with simultaneous high humidity, there is a risk that the sintered metal filter may become clogged and thus impair the functionality of the detector. In this case, the detector must not be used in this environment.
Typical Types of Fires and Released Gases
Sources of Interferences
No False Alarms due to Interfering Signals
Interferences caused by natural outgassing of conveyed materials or exhaust gases from conveying vehicles can be tolerated thanks to multi-criteria evaluation. This also applies to historical buildings in which, unlike in contemporary residential or industrial buildings, various types of dust or biological decomposition processes cause interference. No false alarms due to interfering signals Interferences caused by natural outgassing of conveyed materials or exhaust gases from conveying vehicles can be tolerated thanks to multi-criteria evaluation. This also applies to historical buildings in which, unlike in contemporary residential or industrial buildings, various types of dust or biological decomposition processes cause disruption. In principle, the signal spectrum customary on site is first recorded during commissioning. These findings are taken into account for the parameterization of the detectors.