| 1. |
- Arias, Silvia, et al.
(författare)
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Virtual Reality Evacuation Experiments on Way-Finding Systems for the Future Circular Collider
- 2019
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Ingår i: Fire Technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 55, s. 2319-2340
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Tidskriftsartikel (refereegranskat)abstract
- Evacuation times can be shortened in fire scenarios if people choose appropriate routes. Way-finding systems can be used to aid this process, thus their effectiveness needs to be evaluated. In the present study, the way-finding evacuation systems of the Future Circular Collider (FCC) of the European Organization for Nuclear Research (CERN) are investigated as its evacuation design presents several challenges from the fire safety perspective. To perform a comparison of different evacuation design solutions, a set of Virtual Reality (VR) experiments involving a total of 111 participants was performed. VR was used because the FCC facility is not built yet, and it allows for high experimental control and cost-effectiveness for comparisons of way-finding systems. The VR experiments reproduced a hypothetical fire emergency in which participants’ egress behaviour was investigated. Three scenarios were represented, each of them adopting different evacuation safety concepts and way-finding systems. Different installations were included in the scenarios, such as scenario (1) flashing lights, scenario (2) static or dynamic signage (i.e. active and dissuasive signage indicating the direction towards or away from the danger) and scenario (3) a robot placed on a monorail on the vault of the tunnel, able to localize people in the tunnel and provide way-guidance information. Results show that the combination of red flashing lights at the exits, dynamic signage and a robot equipped with green flashing lights yielded the highest compliance to the way-finding intent of the system (92.6% compliance vs 62.9% and 77.5% for scenarios 1 and 2 respectively).
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| 2. |
- Arvidson, Magnus
(författare)
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The Response Time of Different SprinklerGlass Bulbs in a Residential Room FireScenario
- 2018
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 54:5, s. 1265-1282
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Tidskriftsartikel (refereegranskat)abstract
- The response time of fire sprinklers is essential for their performance,especially in applications where life safety protection is desired. The earlier the sprin-kler activates, the smaller the size of the fire. Most commercial residential sprinklersare fitted with 3 mm, 68C glass bulbs. However, thinner sprinkler glass bulbs withlower operating temperatures are available. The aim of this study was to determinethe response time—and the corresponding heat release rate—of different glass bulbsin a residential room fire scenario. A series of tests were conducted inside a compart-ment measuring 3.66 m by 3.66 m having a ceiling height of 2.5 m. The compartmentwas either enclosed or had two walls removed to provide a more ventilated scenario.A propane gas burner was positioned at one of the corners. The mass flow rate ofthe gas was controlled such that either ‘slow’, ‘medium’ or ‘fast’ fire growth rate sce-narios were simulated. In each test, nine Response Time Index (RTI) and operatingtemperature combinations were tested. Each test was replicated three times. In addi-tion, two commercial fire detectors were tested. The results show that the fire is con-siderably smaller upon activation with a combination of a low RTI and a lowoperating temperature, as compared to the 3 mm, 68C glass bulb typically used forresidential sprinklers. The operating temperature proved to have a larger impact onthe results than the RTI. The heat from the fire was typically detected by the firedetectors prior to the activation of the sprinkler glass bulbs, especially for the ‘slow’and ‘medium’ fire growth rate scenarios.
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| 3. |
- Fjellgaard Mikalsen, Ragni, et al.
(författare)
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Extinguishing Smoldering Fires in Wood Pellets with Water Cooling : An Experimental Study
- 2019
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 25:1, s. 257-284
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Tidskriftsartikel (refereegranskat)abstract
- Smoldering fires in stored or transported solid biofuels are very difficult to extinguish. The current study has explored heat extraction from the combustion zone as a method for extinguishing such flameless fires. Heat extraction from the sample was made feasible using water flowing through a metal pipe located inside the sample. The fuel container was a steel cylinder with insulated side walls, open at the top and heated from below. Wood pellets (1.25 kg, 1.8 l) was used as fuel. Results from small-scale experiments provide proof-of-concept of cooling as a new extinguishing method for smoldering fires. During self-sustained smoldering with heat production in the range 0 W to 60 W, the heat loss to the cooling unit was in the range 5 W to 20 W. There were only marginal differences between non-extinguished and extinguished cases. Up-scaling is discussed, cooling could be feasible for preventing smoldering fires in silos.
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| 4. |
- Forssberg, Martin, et al.
(författare)
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The Variation of Pre-movement Time in Building Evacuation
- 2019
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Ingår i: Fire Technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 55:6, s. 2491-2513
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Tidskriftsartikel (refereegranskat)abstract
- In order to provide a reliable evacuation design assessment, data showing the variation in pre-movement time is of vital importance. The pre-movement time is in many cases regarded as the main time period during an evacuation assessment. Therefore, forty unannounced evacuation experiments for six different occupancies were analysed to quantify pre-movement time during building evacuation, i.e., the time taken between receiving the first cue and initiation of movement towards an exit during evacuation. The occupancies were office, cinema theatres, restaurants, department stores and night clubs. The occupancies were equipped with different types of evacuation alarm systems. The study resulted in 2486 data points for the pre-movement time. The pre-movement times were matched to statistical distributions to describe the variation. It was found that the pre-movement times in most cases could be represented with a lognormal or loglogistic distribution typically having a rapid initial increase representing the phase when people start reacting, which is followed by a less steep decrease representing the phase when some people linger before evacuating. Most reliable data are provided for the cinema theatre experiments which included 1954 data points from 30 experiments. The paper also presents a structure for performing an assessment of video recorded evacuation experiment determining actions, relevant time data and fitting a statistical distribution to the data. The new information provided in the paper can help fire safety professionals to more accurately predict the time to evacuate different premises.
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| 5. |
- Fridolf, Karl, et al.
(författare)
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Evacuation of a Metro Train in an Underground Rail Transportation System : Flow Rate Capacity of Train Exits, Tunnel Walking Speeds and Exit Choice
- 2015
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 52:5, s. 1481-1518
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Tidskriftsartikel (refereegranskat)abstract
- Including in total 135 participants in the ages 19–69 years (recruited from the general public), an unannounced full-scale field evacuation experiment was performed in the Stockholm underground metro system on the night between October 17 and 18, 2014. The purpose was to collect data on the flow rate of people in train exits during the evacuation of a train in a tunnel and on the walking speed of people when moving long distances on an uneven surface in a tunnel, and to study exit choice and behaviour during an evacuation. Consequently, the experiment involved the evacuation of a rail car (a Bombardier C20 train) in a tunnel as well as the subsequent evacuation of the tunnel itself; the latter meant that the participants either could evacuate to the closest station (~400 m) or to an available emergency exit (~200 m). Among other things, the experiment demonstrated that the averaged flow rates of people in the train exits varied between 0.19 p/s and 0.22 p/s (0.14–0.16 p/m s when considering the train exit width of 1.4 m) and that the averaged walking speeds in the tunnel varied between 1.1 m/s and 1.2 m/s (no smoke present). Furthermore, all 135 participants found and used the available emergency exit, which had been equipped with a technical system consisting of a loudspeaker that broadcasted a combined alarm signal and a pre-recorded voice message.
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| 6. |
- Gehandler, Jonatan, et al.
(författare)
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Limit-Based Fire Hazard Model for Evaluating Tunnel Life Safety
- 2015
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 51:3, s. 585-614
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Tidskriftsartikel (refereegranskat)abstract
- Despite the simple one-dimensional symmetry of a tunnel with a longitudinal ventilation flow, risk analysis often comprises resource intensive and complex calculations. The purpose of this article is to present a simple yet precise limit-based model for assessing the possibility for a safe tunnel evacuation. To estimate the model uncertainty, fire dynamics calculations were compared to experimental data. The calculations performed well compared to experimental test data, showing an average difference between 5 and 40% in predicting the time available for evacuation, when criteria for visibility, air temperature, CO, CO2 and O2 concentration and heat flux were calculated. For steadily growing fires, visibility showed a low sensitivity to variability in input parameters with a relative difference at 9% compared to experimental data. Due to several factors it was not possible to estimate the accuracy of HCN calculations. Visualizing the hazards in a time–distance diagram revealed visibility to be the key indicator for calculating ASET for a broad set of plausible input parameters. This resulted in a simple expression for calculating ASET and consequently a simple condition for evaluating life safety.
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| 7. |
- Heidari, Mohammad, et al.
(författare)
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Probabilistic Study of the Resistance of a Simply-Supported Reinforced Concrete Slab According to Eurocode Parametric Fire
- 2019
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 55:4, s. 1377-1404
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Tidskriftsartikel (refereegranskat)abstract
- We present the application of a simple probabilistic methodology to determine the reliability of a structural element exposed to fire when designed following Eurocode 1-1-2 (EC1). Eurocodes are being used extensively within the European Union in the design of many buildings and structures. Here, the methodology is applied to a simply-supported, reinforced concrete slab 180 mm thick, with a standard load bearing fire resistance of 90 min. The slab is subjected to a fire in an office compartment of 420 m2 floor area and 4 m height. Temperature time curves are produced using the EC1 parametric fire curve, which assumes uniform temperature and a uniform burning condition for the fire. Heat transfer calculations identify the plausible worst case scenarios in terms of maximum rebar temperature. We found that a ventilation-controlled fire with opening factor 0.02 m1/2 results in a maximum rebar temperature of 448°C after 102 min of fire exposure. Sensitivity analyses to the main parameters in the EC1 fire curves and in the EC1 heat transfer calculations are performed using a one-at-a-time (OAT) method. The failure probability is then calculated for a series of input parameters using the Monte Carlo method. The results show that this slab has a 0.3% probability of failure when the compartment is designed with all layers of safety in place (detection and sprinkler systems, safe access route, and fire fighting devices are available). Unavailability of sprinkler systems results in a 1% probability of failure. When both sprinkler system and detection are not available in the building, the probability of failure is 8%. This novel study conducts for the first time a probabilistic calculation using the EC1 parametric curve, helping engineers to identify the most critical design fires and the probabilistic resistance assumed in EC1.
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| 8. |
- Hellebuyck, Denis H., et al.
(författare)
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Fire Behaviour of Less-Combustible Dielectric Liquids in a Nuclear Facility
- 2016
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Ingår i: Fire Technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 52:2, s. 289-308
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Tidskriftsartikel (refereegranskat)abstract
- Transformers, modulators and other high voltage electrical equipment are traditionally filled with mineral oil, which serves as a coolant and dielectric insulator. A rising trend is observed globally towards the adoption of less-combustible, bio-degradable transformer liquids at ever increasing voltages and power ratings. This paper presents a study of the fire behavior of five different dielectric transformer coolants: mineral oil, silicone liquid, synthetic ester, and two natural esters. Two types of tests were performed: comparative small-scale tests with two types of pans in the Cone Calorimeter (ISO 5660-1), and intermediate-scale pool fire experiments under the hood of an oxygen consumption calorimeter. The data obtained in this study are used in a fire engineering analysis of the evacuation and smoke removal from the 5900 m2 gallery in the planned European Spallation Source in Lund, Sweden. The comparative results indicate a wide range of fire properties for the tested liquids. The heat release rates calculated from the Cone Calorimeter experiments are reasonably consistent with tabulated values, except for the silicone liquid. The latter forms a crust on the liquid surface which significantly impedes combustion. Heat losses from the burning surface to cooler liquid below and pan boundaries have a significant effect on the burning behavior. These scale-dependent phenomena imply that great care should be taken in using small-scale burning data in a fire engineering analysis. Additional work is needed to gain a better understanding of the relation between small-scale tests and large-scale tests, and between the behavior of these liquids in pool fire experiments and that in real fires.
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| 9. |
- Ingason, Haukur, et al.
(författare)
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A New Methodology of Design Fires for Train Carriages Based on Exponential Curve Method
- 2016
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Ingår i: Fire technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 52:5, s. 1449-1464
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Tidskriftsartikel (refereegranskat)abstract
- Design fires have great influences on the fire safety concepts and safety measures, and are the basis for any assessment and calculation in tunnel fire safety design. A new methodology of design fires for individual train carriages is proposed based on the exponential design fire curve method and state-of-the-art fire research. The three key parameters required for construction of a design fire are the maximum heat release rate, time to maximum heat release rate, and energy content. An overview of the full scale train carriage fire tests is given and the results show that the maximum heat release rate is in a range of 7 MW to 77 MW and the time to reach the maximum heat release rate varies from 7 min to 118 min. The method could be employed to one single train carriage or several carriages, and alternatively one carriage could be divided into several individual sections. To illustrate the use of the methodology, several engineering applications are presented, including design fires for a metro train carriage with a maximum heat release rate of 77 MW, a double-deck railway train carriage with a maximum heat release rate of 60 MW and a tram carriage with a maximum heat release rate of 28 MW. The main objective is to provide practicing engineers with a flexible and reliable methodology to make design fires for individual train carriages in performance-based tunnel fire safety design.
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| 10. |
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