• Gas measurement ports are provided, for optional measurements of toxic gases.
• Cabinet designed with a standard 19" rack, for simple addition of gas analysers, chart recorder and other control units.
• Air cooled radiometer for furnace flux calibration.
The FTT SDC is supplied with a software package called SmokeBox, which is designed as a data acquisition and presentation package allowing either manual or automatic control. This enables a more efficient use of the instrument, leading to larger daily throughput of testing and enhanced quality graphical data presentation. ‘SmokeBox’ is a Microsoft Windows based package which collects test data and assists with all calibration routines.
According to EN 455452, the optical density of flat products, i.e. interior walls, floor coverings, seat backs and seat coverings should be determined using the closed chamber according to EN ISO 56592. The smoke opacity during the combustion of the material is
FIRE TESTING TECHNOLOGY
determined measuring the attenuation of a white light beam by the effluents. The obscuration produced from the smoke is measured as a fraction of the light intensity reaching the photometric detector in the presence of smoke to the value corresponding to the luminous transmission in the absence of smoke before the start of the test.
Two different levels of irradiance have been standardised, depending on the application of the product: • 50kW/m2
with no additional gas ignition source.
• 25kW/m2 with an additional gas ignition source.
The exposure conditions of the test specimen in the smoke chamber are radiant heat with or without application of a pilot flame. For large area products such as walls and ceilings, the test specimens shall be exposed to radiant heat flux conditions that simulate a developed stage of a fire; that is a heat flux of 50 kW/m2
without a pilot flame.
For floor coverings that generally receive lower levels of radiant heat during a fire, the test specimens shall be
exposed to a radiant heat flux of 25 kW/m2
with a pilot flame.
The optical density of the smoke produced is measured continuously by an optical system. Toxic effluents are analysed using FTIR Spectroscopy. For assessment of toxic gases from railway products the Conventional Index of Toxicity (CIT) is used which is always calculated from test data and is dimensionless. The analysis of the spectrum collected during the test determines the concentration of gases. According to EN 455452 the analysis is carried out using the equipment and the procedures for testing and calibration described in ISO 19702.
The 8 gas components need to be analysed and their reference concentrations (see Table 8).
FTT FTIR is a modular construction that typically comprises of FTIR gas analyser, heated sampling unit and an industrial PC which are mounted in a 19” cabin. The FTIR gas analyser is an integral part of the system which allows simultaneous measurement of multiple gas compounds.
Typically concentrations of H2 SO2, NO, NO2
O, CO2
, CO, , HCl, HF, HBr, HCN, NH3 , etc.
are continuously measured. The FTIR gas analyser has a multipass sample cell which is heated to 180 °C and features gold plated mirrors with protective MgF2 coating which ensures high performance even in high water vapour concentrations or corrosive gases.
The advanced, easytouse software provides outstanding analytical performance. It analyses the sample spectrum using sophisticated chemometrics. It is capable of simultaneous detection, identification and quantification of different gas components.
Figure 10: FTT Smoke Density Chamber and FTIR 15
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