Design car fire size based on fire statistics and experimental data

Passenger vehicle fires present a significant fire hazard in enclosed car parks. Accordingly, this hazard is often used as a design fire scenario for the application of fire protection systems. Specific fire protection standards, like NFPA 88A:2019 and NFPA 502:2020 in the United States (US) or BS 7346-7:2013, NBN 21-208-2:2014, VDI 6019-1:2006, NEN 6098:2010 and ITB 493:2015 in Europe, provide varying requirements for car park fire protection. Car parks fire strategies, especially when smoke control systems are used, often make use of performance-based methods, in which fire growth (ie, heat release rate [HRR]) plays a fundamental role. The chosen HRR can influence the specification of car park construction and on smoke control system calculations. This article presents a review of 44 full-scale car fire tests together with Polish and British passenger car fire statistics from the last 8 years. Based on the collected data and the averaged tests, HRR values provided in this article could assist local authorities and stakeholders determine optimal fire safety design criteria for car parks.     

Visualization of room fire induced smoke movement and flow in a corridor

A study was conducted of the smoke and flow field in a corridor subject to a room fire. The study was conducted using a scale model of roughly 0.35 m in height. The effect of corridor-exit doorway width was recorded while the room doorway and fire-room temperature were maintained constant. Smoke was generated from cotton wads soaked with titanium tetrachloride which produces white particles of titanium dioxide. By this means, the smoke layer resulting from the room fire and the corridor flow characteristics were visualized. The results show the lowering interface of the corridor smoke layer with decreasing corridor-exit door width. Also a four-layer horizontal counter-current flow pattern was displayed and shown to result from a restriction (e.g. soffit) at the corridor exit. The mixing of the incoming cold flow and exiting hot flow at the corridor exit was observed to be shedding vortices swept into the cold floor jet. Results based on velocity measurements and smoke observations are presented for the corridor smoke layer height and doorway neutral-plane heights. The limitations of current predictive models are demonstrated for layer-heights and flow rates for the room and corridor experiments.     

Experimental determination of fire heat release rate with OC and CDG calorimetry for ventilated compartments fire scenario

This research deals with the experimental determination of the heat release rate (HRR) of fires in mechanically ventilated compartments based on oxygen consumption (OC) and carbon dioxide generation (CDG) calorimetry. It proposes formulations for fire in force‐ventilated compartments on the same basis as the relations established for hood calorimetry in an open atmosphere but considering inertia and unsteady behavior of the fire via the time variation mass of O₂ and CO₂ in the compartment. The value of the new formulations of HRR has been tested in two series of propane gas fire experiments performed in a large‐scale facility. The first series involves a fire scenario with one compartment, and the second series, a fire scenario with three compartments connected to each other by doorways. In the first test series, the OC and CDG formulations for HRR are assessed. In the second test series, the OC and CDG formulations are presented with two approaches to definition of the control volume: approach involving three rooms and the flow rate in the ventilation network and approach involving only the fire room and the flow rate through the doorways. On the basis of the fire experiments considered, the most accurate method (accuracy to within 10%) for determining the HRR is the CDG formulation with approach for the control volume without considering the flow rates at the doorways. This analysis points out the different features of each method (OC and CDG) and thoroughly discusses their advantages and drawbacks. The overall analysis allows guidelines to be formulated for fire HRR calculation in confined and ventilated compartments. Copyright © 2013 John Wiley & Sons, Ltd.     

Toxic gas and smoke assessment studies on vinyl floor covering with the fire propagation test

The Fire Propagation Test (BS 476 Part 6) has been used with the discharge of combustion products into a small test room, to provide a fire hazard assessment of some polyvinylchloride floor covering systems, and includes measurements of fire propagation, smoke, CO and HCI production. Particular attention has been given to the change in the HCI concentration of the Room atmosphere during the test and the influence of relative humidity and the nature of the surface linings of the room. The results have been discussed as a contribution to the understanding of the role of HCI in toxicity of fire atmospheres. Some approaches for improving further the reproducibility of the test method are indicated and support is given to the Japanese proposal that such a test be standardized to enable comparison of fire hazard potential of lining systems used in buildings.     

Assessing smoke toxicity of burning combustibles by four expressions for fractional effective dose

Toxicity of smoke generated in a fire is difficult to measure accurately. That is because gas sensors for measuring rapidly varying concentrations of toxic gases are not yet developed. Simple expressions are searched for quick measurement in assessing smoke toxicity practically. Four equations on calculating fractional effective dose (FED) related to toxic effluents were reported in the literature, each based on different assumptions. FED value was proposed to be calculated based on peak carbon monoxide concentration and peak carbon dioxide concentration, and transient carbon monoxide, carbon dioxide, and oxygen concentrations. The four values were compared in this article using literature data on toxic gases from different materials measured by (i) cone calorimeter; (ii) full-scale burning tests; and (iii) tunnel full-scale tests. Measured carbon monoxide, carbon dioxide, and oxygen concentrations by standard equipment of oxygen consumption calorimeters were used to calculate the four FED values. It is found that the values of FED based on peak carbon monoxide and carbon dioxide concentrations (denoted as FED₂) are similar to the average values of FED calculated from the updated equation in the literature using the oxygen consumption calorimeters. Putting the values of FED₂ in fire safety design guides is then recommended.     

Smoke data from the Cone Calorimeter for comparison with the room fire test

Smoke production in the full–scale room fire test ISO 9705 (Commonly referred to as the Room Corner Test) and in the Cone Calorimeter ISO 5660 has been analysed for three sets of building products comprising a total of 28 products. The smoke production may be critical for the fire classification of surface products since some products produce large amounts of smoke in the room fire test even if they do not reach flashover within 20 min. Several smoke parameters in the Cone Calorimeter and the room fire test have been analysed. Good correlations have been obtained when the products are divided into two groups: products with more than 10 min to flashover in the room fire test and those with less than 10 min. These two time categories correspond to the two heat output levels in the room fire test: 100 kW for the first 10 min and then 300 kW up to 20 min. For products with more than 10 min to flashover the average rate of smoke production and the total smoke production seem to be useful parameters for predictions of smoke release in the room fire test. Both parameters have good correlations between data from the Cone Calorimeter and the room fire test. For products with less than 10 min to flashover no parameter seems to give useful predictions. For all products evaluated together, the correlations are not so good, but the same regression lines as for products with more than 10 min might be used as a first rough estimate. In this case the total smoke production in the Cone Calorimeter could be used to estimate the total smoke production in the room fire test for different building products, independent of their estimated time to flashover. It is suggested that the average rate of smoke production and the total smoke production from the Cone Calorimeter is reported in addition to the mass-based specific extinction area. This will be helpful in predicting smoke release in the room fire test and will also make the data on smoke release analogous to those on heat release.     

Investigation of smoke gases and temperatures during car fire – large‐scale and small‐scale tests and numerical investigations

The hazards for passengers during vehicle fires result from the increasing temperature and the emitted smoke gases. A fire was set on a car to investigate the development of temperature and of gaseous fire products in the passenger compartment. The study was based on a full‐scale test with a reconstructed scene of a serious car fire. The aim of this work was to identify the conditions for self‐rescuing of passengers during a car fire. A dummy, equipped with several thermocouples, was placed on the driver's seat. Also, the smoke gases were continuously collected through a removable probe sensor corresponding to the nose of the dummy in the passenger compartment and analyzed using Fourier transform infrared spectroscopy. Additionally, several car components were investigated in the smoke density chamber (smoke emission and smoke gas composition). It was found that the toxic gases already reached hazardous levels by 5 min, while the temperatures at the dummy were at that time less than 80 °C. The toxicity of smoke gases was assessed using the fractional effective dose concept. The various experimentally parameters (temperature and smoke gas composition) were implemented into numerical simulations with fire dynamics simulator. Both the experimental data and the numerical simulations are presented and discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

The dynamic flammability and toxicity of magnesium hydroxide filled intumescent fire retardant polypropylene

The flammability properties of an intumescent fire retardant polypropylene added with magnesium hydroxide was discussed in this study. To evaluate the flammability of the material, limit oxygen index, smoke emission, tensile strength, and our exploitation dynamic flammability evaluation system, tests were assessed in experiments. The results showed that the intumescent flame retardant ammonium polyphosphate-filled polypropylene has superior flammability properties but higher carbon oxide (CO) concentration and smoke density. By adding some magnesium hydroxide additives in intumescent fire retarded polypropylene, the smoke density and CO concentration decrease; and the compound also has superior fire properties. It is concluded that intumescent system and magnesium hydroxide additives are effective on improving combustion properties for polypropylene. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:989–995, 1998     

Effect of environmental conditions on smoke propagation

This paper examines the influence of oxygen and environmental temperature on the generation of smoke from burning polystyrene sheet. The experimentation was performed using a Stanton Redcroft HFTA linked to a Stanton Redcroft FTB Smoke Box. The results showed that different forms of smoke were formed depending upon the environmental conditions. For example, in oxygen-enriched atmospheres and at elevated environmental temperatures, as in spacecraft fires, large smoke particles were formed with a lower level of obscuration. This phenomenon was accompanied by higher rates of burn and high fire temperatures. At lower oxygen contents, as in real-life fire conditions, close to the Critical Oxygen Index, finer smoke particles were formed which gave a higher level of obscuration. The time to maximum obscuration was comparatively long.     

Effects of additives on fire properties of polyethylene

Low-density polyethylene, with and without an antimony–bromine synergistic fire retardant or aluminium hydroxide, was subjected to standard fire tests and to experiments which determined the smoke and harmful fumes emitted on overheating. Both additives improved most fire properties but the fire retardant increased the smoke generated by intense radiant heat. The onset of smoke, flammable gas, carbon monoxide and acids was generally delayed by the additives. The total amounts and maximum values of these volatiles were lessened. Sample weight and form affect the results of these experiments. Observations during heating show that the additives reduce spreading of the melt, thus reducing the surface area available for oxidation.     

Experimental study of smoke effects on energized electrical cabinets located nearby a lubricant oil pool fire

This paper presents an experimental study of smoke exposure effects on potential malfunction of three electrical cabinets located nearby an oil pool fire. This study was performed as part of the PRISME‐2 international OECD project. Lubricant oil was used as fire source, and three real energized electrical cabinets were used as targets exposed to smoke in the adjacent room to the fire room. The main fire properties, as well as the fire consequences, such as gas temperatures and smoke concentrations in the rooms, and the cabinets are presented in detail. The heat release rate was thus assessed at around 500 kW for nearly all the fire duration, and maximum gas temperatures reached 300°C in the fire room, and 120°C in the adjacent room. Moreover, the maximum gas temperatures and soot mass concentrations inside the cabinets ranged from 90 to 120°C and from 0.3 to 1 g/m³, respectively. Nevertheless, continuous electrical monitoring of the three cabinets did not highlight malfunction. After the experiment, monitoring test of the cabinets was conducted to investigate the potential effects. The isolation resistance of electrical circuits on the most severe smoke exposed cabinet reduced during the monitoring test. It seemed the soot deposition have caused it.     

Short Communication: Aircraft interior panels tested according to the maritime high-speed craft code

The fire standard for aircraft interior panels has been compared to the corresponding marine standard with respect to smoke emission and heat release rate. This has been performed by testing an aircraft panel approved by the Federal Aviation Administration according to one of the International Maritime Organization standards for High-Speed Craft, according to the full-scale room fire test, ISO 9705. The test showed that even if the panel met the strict requirements of the Federal Aviation Administration it did not fulfil the apparently even stricter requirements of the International Maritime Organization. The panel failed on several accounts, including smoke production, heat release and structural integrity. © 1997 John Wiley & Sons, Ltd.     

Physical modelling fire performance of wall-covering materials

A small-scale enclosure was constructed for characterizing the contribution of interior finish wall-lining materials to fire growth in compartments. The enclosure was based upon refinements to a design devised by scientists at the National Institute for Standards and Technology for quarter-scale modelling of room fire tests on interior-finish materials. A large volume of evidence is presented demonstrating how this small-scale enclosure could provide the information about surface flammability, heat release, smoke generation and contribution to fire growth that is required for a reasonable assessment of the fire performance of interior wall-finish materials.     

Evaluation of the room smoke filling time for fire plumes: Influence of the room geometry

The article examines numerically and theoretically the effects of room aspect ratio on the fire smoke filling process. It aims to evaluate the two-zone models used in fire safety engineering to predict the smoke filling times. Using Fire Dynamics Simulator, numerical simulations are performed and compared to a simplified zone model. The results show that the two-zone model overestimates the smoke filling time in the case of a compartment with a large surface area. To improve the predictions of two-zone models, simple correlations are established for the duration of the phenomena occurring before the formation of a two-layer stratification in a fire compartment. These new correlations allow the zone model to be significantly improved.     

Modeling of NBS mattress tests with the harvard mark V fire simulation

NBS burned eleven mattresses made up with bedding in two different rooms, typical of a residential bedroom and a nursing home patient room, respectively. Seven of the mattresses flamed and burned vigorously, the other four were of a construction or so heavily flame-inhibited that they only smoldered. The burning behavior of the seven that flamed was modeled with the Harvard Mark V fire simulation. The experimental burn behavior for tests conducted in one room was well reproduced using only total weight of combustible, surface area and heat of combustion. Smoke production values were found to have little effect on the predicted behavior except for the smoke production itself. Fires in a second room, whose ventilation was intentionally restricted by the configuration of the adjoining space, could not be as well reproduced by the present, single-room fire model. During this study several changes were made to the simulation. The most significant change was the inclusion of mixing of the hot exiting fire gases with the cold incoming air. As a part of this, the inter-layer radiation exchange was reformulated to include the effect of smoke contamination of the lower layer. The reformulation of the radiation model has a marked effect on the predicted upper layer gas temperatures, generally improving the quality of the simulation.     

Modified carbon‐dioxide measurement to predict the heat release rate of fire burning in a compartment based on the three‐zone model

The heat release rate (HRR) of fuels has been described as the single important variable of fuels in fire hazard, and the HRR experimental measurement remains a key issue in fire science. A modified carbon‐dioxide generation (CDG) method, applying a three‐zone smoke model, is developed to predict the HRR of gas, liquid, and solid fuel fires. The three‐zone smoke model with three layers is determined by the vertical thermal stratification, and their physical thermal properties are computed. The application of modified method on typical gas fuel, liquid fuel, and simple solid‐fuel fires is verified. The prediction accuracy is examined quantitatively by the cosine similarity comparison of predicted results with the experimental data. In addition, the ventilation effects on the predicted results are also explored. Results show that the application of three‐zone model improves the HRR prediction accuracy, because it can accurately capture the mixing behavior from the upper layer to the lower layer. The effect of ventilation on modified CDG method is positive as the ventilation enhances the smoke mixing and the smoke distribution in each layer is relatively uniform.     

Heat release rate in evaluation of conveyor belts in full-scale fire tests

The theoretical bases for calculation of heat release rate during burning of conveyor belts in the fire-testing gallery has been presented. Taking as an example the results of measurements of oxygen, carbon dioxide and monoxide content in the products of combustion of conveyor belts during the testing of their flammability in the full-scale fire gallery, the possibility has been demonstrated for using the calculations of heat release rate in an assessment of conveyor belt flammability. The total quantity of heat released during the belt fire in the experimental gallery can provide the basis to develop a new method of testing as well as the criteria for assessment of fire resistance of the conveyor belts using oxygen consumption calorimetry. © 1997 John Wiley & Sons, Ltd.     

Advantages and challenges with using hypoxic air venting as fire protection

The use of hypoxic air venting system as fire protection is increasing and is sometimes used to replace traditional extinguishing systems. An oxygen level of 15% is generally used because a lower concentration could pose serious health risks. On the request of the Swedish Radiation Safety Authority, a literature review was conducted to determine advantages and challenges with the system and further research needs. The main advantages with a reduced oxygen environment are the reduced probability of ignition and lowered heat release rate. However, at 15% oxygen level, risk for fire still exists, and the system cannot be seen as an alternative to extinguishing systems. Reduced oxygen environment also results in higher production rates of soot and smoke, and there is limited knowledge regarding the effect of fuel configuration and fire behavior of products. In addition, a first evaluation of the test method specified in the hypoxic air venting standards was carried out through testing. The testing showed that the particleboard passed the test criteria at normal atmosphere even though it is commonly known that a particleboard burns in normal air. It is concluded that the test method has deficiencies, and there is clearly a need for development of the test method to guarantee safety levels. © 2013 The Authors. Fire and Materials published by John Wiley & Sons, Ltd.     

Use of the ARGOS fire risk analysis model for studying chinese restaurant fires

The fire risk in Chinese restaurants in Hong Kong is analyzed using the ARGOS fire risk analysis model developed at the Danish Institute of Fire Technology. A sample size of fifteen Chinese restaurants with different floor areas and fire load densities is considered. Fire simulations are performed for two cases by assuming a PU foam furniture fire occurring in the dining hall and a kerosene fire in the kitchen. Correlations are derived between the floor area and the predicted maximum hot gas temperature, the corresponding smoke layer interface height and the cost of damaged stock in the restaurants. The effectiveness of fire protection systems including sprinkler systems and smoke vents in controlling the fire is also discussed.     

某大型物流交易中心消防性能化设计探讨

以某大型物流交易中心为研究对象,对类似大型建筑在人员安全疏散、防火分区、防排烟等方面存在的设计难点及采用的消防性能化设计思路进行分析介绍,通过火灾场景分析、火灾蔓延及烟气流动状态分析和人员安全疏散分析对采用的消防性能化设计进行介绍,为解决类似大型建筑消防设计的困难提供一些参考。