Tunnel thermoplastic membranes are widely used in road tunnels to divert water leakage from the rock. The Swedish Transport Administration specifies several functional requirements for these membranes, including fire safety. Higher fire performance often compromises other properties such as strength and durability, which is why membranes with lower fire classification, E, are commonly used. An E- class membrane is tested according to EN ISO 11925-2, involving exposure to a small flame for 15 seconds, with flame spread limited to 150 mm within 20 seconds.

During construction, membranes are typically installed in large sections before shotcrete application, leaving them temporarily unprotected. This raises concerns about fire risks, as construction vehicles can produce heat release rates of several megawatts. In installation spaces, membranes may remain exposed in the finished tunnel, but the potential fire load is smaller (e.g., an electrical cabinet of about 200 kW).

This project evaluated the fire behavior of E-classified membranes through tunnel fire tests. Six thermoplastic (PVC, polyethylene, and polyolefin) membranes, 1.1–2.1 mm thick and surface density 1.1–2.7 kg/m², were tested in a square tunnel with side 2 m and length 60 m under four fire scenarios. All membranes met class E requirements for surface and edge exposure with a small flame. No ignition occurred in the radiation scenario (200 kW at 0.8 m distance). For direct exposure of 200 kW (equivalent to 3 MW full scale), membrane contribution was marginal. At 750 kW (equivalent to ~13 MW full scale), contribution was brief before melting created a natural fire break. No continuous fire propagation along the membrane section was observed.

The quantitative analysis of fire effluents is essential for assessing both toxic hazards and combustion chemistry. ISO/TS 21397 specifies the use of Fourier transform infrared (FTIR) spectroscopy coupled to cone calorimeter tests for the online measurement of fire gases. To evaluate the robustness of this method, an interlaboratory round robin was conducted under the framework of ISO/TC 92. Six laboratories participated, four of which provided complete FTIR datasets. Four polymers were selected to represent different effluent profiles: high-density polyethylene (HDPE), polymethyl methacrylate (PMMA), polyamide 6.6 (PA 6.6), and unplasticised polyvinyl chloride (PVC). Each laboratory performed three replicate cone calorimeter tests at 50 kW/m2. Combustion parameters (peak heat release rate, total heat release, effective heat of combustion) and effluent species were analysed. Qualitative results showed consistent identification of expected major species: carbon dioxide (CO2) and carbon monoxide (CO) for all polymers, nitric oxide (NO) for PA 6.6 and hydrogen chloride (HCl) for PVC. Quantitative analysis focused on maximum concentrations and yields of CO2, CO, NO and HCl. Statistical treatment following ISO 5725 provided complete repeatability and reproducibility values. The results revealed a clear hierarchy in reproducibility: combustion parameters showed the lowest variability, followed by CO2, then CO, with NO and HCl exhibiting higher dispersion. Minor species such as HCN and NO2 were detected inconsistently and excluded from statistical treatment. The study confirms that ISO/TS 21397 yields reproducible data for the major effluents of interest, while highlighting the need for more prescriptive guidance on calibration and quantification methods to further improve interlaboratory agreement

Materials and products age with time and their properties change. It is known that, for example, the mechanical strength may be deteriorated from ageing. To understand the ageing effect on the fire behaviour of materials and products is important to maintain the safety level of the construction or application. In this study, three different sandwich panels with intumescent coatings were selected for a study to evaluate the effect of accelerated ageing on reaction-to-fire properties. The accelerated ageing methods used were thermal exposure in 90°C and moisture exposure in 40°C and 90% RH. Samples were collected from ageing chambers after 1, 2 and 4 weeks. The reaction-to-fire properties were evaluated using the ISO 5660-1 cone calorimeter and the smoke density chamber, EN ISO 5659-2, with FTIR analysis of gas composition. The results show that ageing has an effect on the fire behaviour. Fire properties such as heat release rate and smoke production were unchanged or actually improved. Generally, the time to ignition was longer for the aged samples. The smoke density was affected as well as the smoke toxicity

The increasing severity of wildfires poses significant challenges through the release of greenhouse gases and other harmful gases and particles. Although field measurements exist, there is a lack of systematic data collection to understand the influence of moisture content on the particle and gas emissions of boreal fuels, particularly for European boreal forest fuels. This study investigates the influence of moisture content and fuel type on flaming combustion emission characteristics of surface fuels collected from two Swedish forest types, which share key characteristics with fire-prone forests across the European boreal. The results are based on bench-scale controlled combustion conditions in a cone calorimeter, where gaseous and particle emissions were measured using Fourier Transform Infrared spectroscopy and an Electrical Low-Pressure Impactor, respectively. Moisture content of the fuels only insignificantly affected combustion efficiency, with higher moisture content leading to increased emissions of incomplete combustion products (CO, CH4 and NH3). Thus, although moisture affects the amount of fine fuel consumed in a wildfire, it is not significant for the emissions factors during the flaming combustion. The combustion of mosses was instead significantly less efficient than that of litter for all moisture contents. Average emission factors highlighted clear differences between fuel types, with mosses producing higher CO (87 ± 20 g/kg) and lower CO2 (1350 ± 220 g/kg) compared to litter (47 ± 12 g/kg and 1620 ± 81 g/kg, respectively). Particle emissions were strongly dependent on fuel type with (Formula presented.) of 29 ± 12 g/kg for mosses compared to 98 ± 15 g/kg for Pinus sylvestris needles and twigs

Combustible materials used in marine applications must be verified with regards to the fire performance. The requirements of the materials are related to end use application and type of vessel for the installation. However, usually the regulations refer to the IMO FTP Code 2010 for fire test methods and requirements. Reaction-to-fire parameters such as non-combustibility, smoke, toxicity and flame spread are addressed. One reaction-to-fire parameter is not addressed in the FTP Code, the ignitability of the material. Historically, it has been considered that if the material fulfils the requirements in the FTP Code, the ignitability test is not an issue, since the other test methods are more stringent. This study aims to evaluate the ignitability of seven selected composite materials, using the small flame fire test method according to EN ISO 11925-2.

Materials used for interior parts in buses are today fire classified according to UNECE Regulation 118, evaluating the horizontal and vertical burning rates and the melting behaviour. However, in recent accidents, the smoke has been identified as the critical parameter for deaths. An evaluation has been made of six materials used as interior parts in busses and is presented in this paper. Fire testing was conducted according to UNECE R 118 and smoke production including smoke gas toxicity was further evaluated with the smoke chamber test, EN ISO 5659-2 and EN 17084. All six tested materials fulfilled the requirements of UNECE R 118; however, most materials showed fire properties which are not desirable, such as dark smoke and melting of large burning pieces. The tests with the smoke chamber showed that all materials gave a very high smoke production, in fact a smoke density value of the highest possible for the equipment to measure. This occurred only after a few minutes of test time. Thus, it can be concluded that this high smoke production will, in case of fire in a bus, reduce the visibility, and limit the ability of the passengers to safely evacuate. In addition, several toxic gases were detected in the smoke, both irritants and suffocating gases. © 2022 The Authors.

The demands on bus interior products have increased with increasing sustainability, circularity and a reduction of harmful substances, today’s materials must be improved with regards of additives, such as flame retardants. A comprehensive study was made to evaluate the possibility to use phosphorous flame retardants (FRs) instead of the commonly used halogenated FRs compounded with ABS. The study showed that the fire performance could be improved with phosphorous FRs regarding heat release and smoke production. However, it was noted that the smoke production still was high, and that the smoke density was highest possible, i.e., no visibility through the smoke layer. Further testing of today’s bus interior materials showed that the high smoke density was achieved already after a few minutes of test time. Thus, it can be concluded that, in case of a fire, the visibility in the bus will be reduced and limit the ability of the passengers to safely evacuate. In addition, several toxic gases were detected in the smoke, both irritants and suffocating gases. The bus fire regulation R118 for interior materials basically deals with burning rate and melting through a fine mesh. Critical fire parameters such as smoke production and smoke toxicity is not dealt with. The R118 regulation need to be improved with these critical parameters in order to have fire safe materials inside the bus.

This study provides an analysis on the fire safety of passengers and the fire protection of coaches and buses. A brief review of major bus fire incidents, an overview of current regulations in Europe, and their limitations are presented. The study finds that the current small-scale fire test methods described in UN ECE Reg No. 118 need to be replaced by test methods that can assess the reaction to fire of materials when exposed to ignition sources of varying sizes. To address these shortcomings, the study proposed an expert recommendation to update the material fire safety requirements and testing for buses. Additional measures are proposed, derived from objectives and strategies applied in other transport sectors, and can be tested through existing European and international standards, which are widely used by several industries. These measures aim to extend the time with tenable conditions for a safe evacuation in case of fire, reduce the degree of damage to buses, reduce the risk for fast and excessive thermal exposure on modern energy carriers needed for a more sustainable transport sector. © 2023 The Authors. 

The phosphorous-based flame retardant additives poly(m-phenylene methylphosphonate) (PMP) and resorcinol bis(diphenyl phosphate) (RDP) are reacted with bisphenol F and aniline–based benzoxazine (BF-a). DSC, rheological analysis, FT-IR, and soxhlet extraction reveal the covalent incorporation of both FR additives—initiating phenols in PMP structure as well as free phenols generated via transesterification reaction in the case of RDP. In contrast to PMP, RDP elongates the processing window but decreases the thermo–mechanical properties. Both additives increase the resistance in reactions against small flames with solely a phosphorous loading of 0.3 wt%, resulting in a V-0 rating and an improvement in the OI value by up to 2% for RDP and 4% for PMP. Both FRs reduce the heat release rate but increase the smoke production and the smoke toxicity in the case of RDP.