Composite panel walls with both combustible and non-combustible cores were subjected to fire resistance test to EN 1364-1. The results revealed that the combustible-core panels started emitting smoke on the unexposed side due to the presence of joints between panels. In some cases the smoke emission started early after the start for the fire exposure. The start of the smoke production period appeared to depend on the fixation of the panels to the furnace frame; three or four sides fixed as per EN 1364-1. The amounts of smoke released indicate that although smoke leakage/production criterion is not currently part of the standard fire-resistance testing protocol it should be assessed when construction elements with combustible components are tested. Otherwise such a barrier may not be considered as a smoke-safe separating element, because model FED calculations indicate a potential threat to the occupants on the unexposed side at a certain set of conditions

Mózer, Vladimír

Smolka, Miroslav

Tofiło, Piotr

English

CTU Open Journal Systems (Czech Technical University, Prague / České vysoké učení technické v Praze)

Applications of Structural Fire Engineering, 15-16 October 2015, Dubrovnik, CroatiaFIRE PERFORMANCE OF COMPOSITE-PANEL SEPARATION WALLSMiroslav Smolkaa, Vladimír Mózera, Piotr Tofiłoba University of Zilina, Faculty of Security Engineering, ul. 1. maja 32, 01026 Zilina, Slovak Republicb Main School of Fire Service, Juliusza Słowackiego 52/54, Warszaw 01-629, PolandAbstractComposite panel walls with both combustible and non-combustible cores were subjected to fireresistance test to EN 1364-1. The results revealed that the combustible-core panels started emittingsmoke on the unexposed side due to the presence of joints between panels. In some cases the smokeemission started early after the start for the fire exposure. The start of the smoke production periodappeared to depend on the fixation of the panels to the furnace frame; three or four sides fixed asper EN 1364-1. The amounts of smoke released indicate that although smoke leakage/productioncriterion is not currently part of the standard fire-resistance testing protocol it should be assessedwhen construction elements with combustible components are tested. Otherwise such a barrier maynot be considered as a smoke-safe separating element, because model FED calculations indicate apotential threat to the occupants on the unexposed side at a certain set of conditions.Keywords: fire resistance, sandwich panels, free edge, smoke emission, fire compartmentation1 INTRODUCTIONThe purpose of fire resistance testing is to verify the fitness of fire separating barriers (typicallywalls and floors) for use as boundaries of fire compartments. Based on the definition ofcompartmentation – The subdivision of a building into relatively small areas so that fire or smokecan be confined to the room or section in which it originates (Code NFPA 232) – the assumption isthat the fire barrier itself is not a contributing element to fire and smoke spread to the safe side.The tests simulate post-flashover fire conditions using the standard temperature/time curve, asexpressed by the European standard fire resistance testing, according to EN 1363-1. Non-loadbearing walls are tested to EN 1364-1. None of these tests are intended to evaluate or quantifysmoke emission from the tested boundaries of fire compartments (Fig. 1).2 FIRE RESISTANCE TESTS WITH ADDITIONAL SMOKE MEASUREMENTSTwo series of experimental fire resistance tests have been carried out to EN 1364-1. Sandwichpanels with steel facings and the cores made of non-combustible insulation (mineral wool – MW)and combustible insulation (polyisocyanurate – PIR) were chosen as examples of non-loadbearingwalls.  Both types are commonly used as part of a fire resistant building envelope and as fireseparating walls within buildings, subjected to CE-marking to EN 14509. Two or three identicalspecimens of each type of product tested using particular installation method were used for the test.In addition to standard measurements and observations, the following phenomena and values weremeasured and/or observed: Observation of smoke emissions from the safe (unexposed) side of the walls tested. Estimate of heat released from the fire (exposed) side of the walls tested, using the actualamount of fuel burned in the test furnace to achieve the EN 1363-1 standard time/temperaturecurve compared to an inert non-combustible aerated concrete wall. Measurement of opacity of smoke and particle distribution emitted to the safe side of thewalls tested. Quantative and qualitative measurements of smoke emitted to the safe side of the walls tested,subsequently analysed for its composition and toxic effects on humans.Results of both series of tests, overview and discussion of results have been published by Smolka etal. in 2013 and 2015. Complete set of results and analysis of smoke emission measurements in fireresistance tests and in small scale using ISO/TR 19700 has been published in the SP Report2014:25 (Blomqvist et al., 2014).Fig. 1 When a segment of a fire separating structure is tested for fire resistance, its contribution to heat andsmoke development to either side is not part of the measurements or observations.3 TESTED PRODUCTS AND INSTALLATION METHODSApart from showing a distinct difference in the above mentioned fire performance measurementsand observations, between the combustible-cored and the non-combustible cored sandwich panelwalls, differences in behaviour between identical specimens were observed. These apparentlyresulted from different methods chosen for installation of the tested walls in the two test series.3.1 Panel walls fixed on three sides with a free vertical edgeFig. 2 Standard mounting of a non-loadbearing wall tested for fire resistance, with a vertical free edge(simulation of a situation that the wall installed in practice will be wider than the 3m tested width)In the first part of the project, the panels were fixed to hot-rolled steel beams using the screwsspecified by the producers, in full accordance with the test method EN 1364-1 (Fig. 2). The fixingmethod used in these tests was chosen to be representative of practice where panels are mounted ona load-bearing steel structure of a building. Two parallel U-shaped hot-rolled steel profiles wereused to simulate the load-bearing building structure. These profiles were welded on one side, andlaid in brackets to allow for thermal expansion on the other side (Fig 3).Fig. 3 The load-bearing steel structure was allowed to expand during the fire resistance test (simulation of asituation that the wall installed in practice will be wider than the 3m tested width)The panels were attached to a fire-protected steel profile as shown in Fig 4.Fig. 4 Panels attached to hot-rolled steel U-profiles simulating the load-bearing building structure3.2 Panel walls fixed on all four sidesDuring the second set of fire resistance experimental walls, the panels were attached to a thin L-shaped steel profiles placed around the perimeter of the walls. No free edge joint was used here toachieve a maximum tightness possible between the furnace and the external environment. This wayof mounting and fixing is not typical for fire resistance testing of non-loadbearing walls, butallowed by the test method. The fixation of the panels to the furnace frame is shown in Fig. 5.Fig. 5 Panels attached to cold-rolled steel L-profiles mounted within the concrete test furnace framesimulating the adjacent concrete floor, ceiling, and walls4 RESULTS: IMPACT OF INSTALLATION ON SMOKE AND HEAT EMISSION4.1 Panel walls fixed on three sides with a free vertical edgeWhen the free-edge installation was used and the panel walls were attached on three edges only, thebehaviour of the tested elements showed that: Two of the four PIR-cored panels displayed heavy smoke emission on the safe (unexposed)side, changing over time erratically. Heat released from the specimens differed; the difference not only being between MW-coredand PIR-cored panel walls, but also among the PIR-cored panel walls themselves. Heat input from the burners seemed inversely proportional to smoke emissions on theunexposed side outside the furnace, comparing different test specimens, as well as comparingdifferent test periods of individual test specimens. The first joint that opened and started to emit visible smoke was the one closer to the freeedge, in all the tests conducted in this series, as shown in Fig. 6. It was apparently due todifferent strain generated inside the tested wall on the joints, resulting from the from heatexpansion of the steel facings.Fig. 6 Panel wall with a free vertical edge: joint placed closer to the free edge was the first to start releasingsmoke in all the tests carried outIn this first series of tests, no smoke capture or analysis was carried out.4.2 Panel walls fixed on all four sidesWhen the free edge was not used and the panel walls were attached on all four sides, the behaviourof the tested elements showed that all three PIR-cored tested walls displayed remarkably similarsmoke emission patterns, with heavy smoke emission starting about 10 minutes and continuingonwards into the tests. Contributions of PIR-core panel walls to heat emission were uniformthroughout the test as well as among the tested specimens.The three tests conducted has not shown any pattern as to which of the two joints would emit smokefirst, as shown in Fig. 7. This was apparently due to the symmetrical fixation of panel walls.Fig. 7 Panel wall without a free vertical edge: any of the two panel joints (or both) could be seen to releasevisible smoke; no pattern was observed as to which of the joints will start emitting smoke firstDuring the second series of tests when all the smoke emitted from the safe side was captured andanalysed, it became apparent that the visible smoke emissions from combustible-core panel wallscorrelated well with the measured concentrations of major combustion gases: CO2, CO, and HCN.Out of the three combustion species, HCN was found the most significant contributor to overalltoxicity (Blomqvist et al., 2014).5 CONCLUSIONSThe first series of fire resistance tests made on sandwich panel walls have shown that metal facedsandwich panels with combustible core do not make inert boundaries of fire compartments. Whenexposed to a fully developed fire form one side, these structures are capable of releasing substantialamounts of smoke to the safe side, or heat to the fire side. These phenomena appear inverselyrelated.The second series of fire resistance tests equipped with unexposed side smoke capture and analysishave shown that visible smoke emissions are accompanied by increased concentrations of majortoxic species: HCN, CO, and CO2.Apart from these confirming results, two distinct emission patterns were observed: erratic smokeemission in the first series and a much more uniform emission pattern in the second series of tests.These appear to be dependent on the two different installation methods used.Required by EN 1364-1, the free edge simulates the wall which is much wider than the standard 3mx 3m tested size; when used, the wall width can be unlimited in practice. The free edge was used inthe first series of tests, which resulted in different mechanical strain induced within the wall fromthermal expansion, and significant smoke emissions from the panel joint placed closer to the freeedge.The second series of tests did not used the free edge, which resulted in symmetrical induced stresson both panel joints, and uniform smoke emissions similar in all the three tested wall specimens.The project has shown that fire resistance tests equipped with smoke capture and instrumentationare capable of quantifying smoke emission in terms of particle distribution, opacity and toxicity.The values obtained can be subsequently used for modelling of real building situations. However,the goal to obtain quality data should not contradict basic requirements of test specimen installation,with potential impact on end use of the tested element of building structure.REFERENCESCODE NFPA 232. Standard for the Protection of Records (2000 Edition).EN 1363-1 Fire resistance tests. Part 1: General requirements. CEN.EN 1364-1 Fire resistance tests for non-loadbearing elements. Part 1: Walls. CEN.EN 14509 Self-supporting double skin metal faced insulating panels - Factory made products —Specifications. CEN.Blomqvist P., Johansson P., Comparison of fire effluent composition between large-scale and small-scaletests with sandwich panels. SP report 2014:25Smolka, M., Mozer, V., Tofilo, P., 2015. Gas and particle effluents released from boundaries of firecompartments: First results and analyses, in Proceedings from the Fire and Materials 2015 Conference,London: Interscience Communications, February 2015.Smolka, M., Suurenbroek Y., 2013. Smoke and heat emissions as the measures of interaction of testedelements with test environment in fire resistance testing, in Interflam conference proceedings, London:Interscience Communications, June 2013.

FIRE PERFORMANCE OF COMPOSITE-PANEL SEPARATION WALLS

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FIRE PERFORMANCE OF COMPOSITE-PANEL SEPARATION WALLS

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