Room Of Fire Origin Research Articles

Simple Equations for Predicting Smoke Filling Time in Fire Rooms with Irregular Ceilings

This paper proposes simple equations for predicting the smoke filling time in the room of fire origin, which may be practically used to evaluate the performance of evacuation safety design of building. The simple equations were developed for the typical types of design fires, i.e. constant, t-square and their combination. Also these equations can be used for rooms having irregular ceilings, whose horizontal section areas change with height. Their prediction capabilities were verified by comparison with the predictions by BRI2002, a two-layer zone model often used as a tool for evacuation safety design. These simple equations are found to have prediction capability almost equivalent to BRI2002 for smoke filling in the room of origin.

How Many People are Exposed to Sublethal Fire Smoke?

A good estimate of the magnitude of the population exposed to fire smoke would be a reality check on the suitability of predicting harm to people from fire through the use of conservatively low fire safety thresholds designed to assure no harm to even vulnerable subpopulations. If this total number of exposed people were far greater than the number of reported victims, then it would be fair to say that the implied safety factors in such a calculation are unreasonably large. Based on analyses of demographic and fire incidence data, it is estimated that between 310,000 and 670,000 people (excluding firefighters) in the U.S. are exposed to fire smoke each year in unwanted home fires alone. This compares to an average of 3,318 home civilian fire deaths and 11,505 civilian fire injuries per year involving smoke inhalation in part or in whole in reported home fires. There are thus 21 to 45 civilians exposed to toxic fire smoke per year for every one with a reported fire injury involving smoke inhalation. It is likely that most of these exposures are brief or are to the dilute smoke that is present outside the room of fire origin, where most survivors are located, and do not result in any noticeable consequences, let alone injury or death.

The Relationship Between Smoke Concentration Some Distance Down the Hallway and the Opening of the Room of Fire Origin

The smoke concentration at a distant location down a hallway as a function of different openings of the room of fire origin is considered. A series of tests is reported and the smoke sustaining (residence) time, the concentration peak and the concentration buildup rate are investigated as functions of the size of the opening. The smoke sustaining (residence) time, the most important factor concerning smoke toxicity, is described by a novel concept, wavelength, in this study. Furthermore, it is worth emphasizing that the smoke concentration at the sampling point exhibits a phenomenon of vibration in the case of the smallest opening during the test.

Fully Involved Enclosure Fires: Effects Of Fuel Type, Fuel Area And Geometry

For the design of fire safety systems, evacuation analysis structural response and external façade performance, the heat release rate history is a primary factor regarding the development of building fires starting from the room of fire origin. This work examines the steady state heat release rate period in enclosures that occurs after the initial growth period ends because either fire has spread to all fuel available or ventilation- controlled conditions have been established. It extends previous important work by identifying how fuel type (e.g. stoichiometric ratio), fuel surface area, room geometry and opening affect the rate of burning. Using recent well-designed experiments in cubic like enclosures and in corridors together with a simple theory, correlations are developed for the rate of pyrolysis, of incoming air flow and of excess pyrolysate. In the course of the analysis, critical areas of research are suggested concerning combustion efficiency, heat fluxes, and effective fuel area involved in pyrolysis

Measurement of doorway flow field in multi-enclosure building fires

This paper discusses fire induced smoke movement and associated species transport in a multi-enclosure compartment building. A set of steady state and transient state fires experiments have been conducted in a full-scale building. The distributions of various physical parameters such as temperature, velocity and species concentration, were measured. Particular attention is given to the flow fields at the doorway which connects the room of fire origin and a corridor. The experimental results indicated the effects of mixing between the hot upper layer smoke and the relatively cool lower layer air in the corridor. Some data processing techniques are also explained.

The Probability of Death in the Room of Fire Origin: an Engineering Formula

The paper presents a partial safety factor approach to the problem of evaluating competing designs for fire safety in the room of fire origin in a building. A partial safety factor is defined as the ratio of the design value to the characteristic value for a load type variable and its inverse for a resistance type variable. The safety criterion considered is the expected number of deaths in the room or, alternatively, the probability of any death. A death is assumed to occur when the time, X between the occurrence of the alerting cue and the onset of untenable conditions is shorter than the time, Y to evacuation.First, a safety index, β is obtained, based on the means and standard deviations of the logarithms of X and Y. Partial safety factors for X and Y can then be calculated.It is further shown that there are theoretical reasons as well as empirical evidence for assuming that X and Y both have approximately a lognormal distribution. There is then a direct connection between the probability of death and...

Closed-Form Equations for Room Smoke Filling During an Initial Fire.

Closed-form equations were derived to calculate the smoke layer height and temperature in the room of fire origin. First of all, a conventional zone type model was introduced and verified against the full-scale experimental data. Then, by using the calculation model, virtual experimental data were created varying the building design parameters such as fire growth rate, floor area and ceiling height. Regression equation was derived for smoke layer temperature using the virtual experimental data that correlates the dependence on building design parameters. As to the smoke layer height, an analytical formula (Tanaka's formula) was verified against virtual experimental data. This type of simple, hand-calculable formula would be useful for practitioners in fire safety engineering design of building for evacuation safety from smoke.

Flames venting externally during full-scale flashover fires: two sample ventilation cases

The effects of burn room ventilation and environmental conditions on venting plumes have been examined during a series of full-scale flashover fires at the Experimental Building Fire Facility of CESARE (Centre for Environmental Safety and Risk Engineering) of Victoria University of Technology. The focus in this paper is on two typical test cases, each corresponding to one of the two ventilation classes examined during this series of fires, namely, Class 1: through-draft (flow through) and Class 2: no-through-draft conditions. These conditions correspond to the open door and window in the burn room, and the closed door and open window, respectively. Three-dimensional temperature contours outside the burn room have been used to study plume dispersion. Total and radiant heat flux measurements, combined with the overall reach and severity of venting flames indicate that flames emerging from the room of fire origin are capable of initiating a secondary fire in the level above. While each fire has a natural periodicity innate to the combustion process itself, any swirling motion of the venting plume has been observed to be caused by a cross-wind.

Experimental analysis of the performance of a multisensor two-stage fire detection and water discharge algorithm

This paper describes the development and performance of a multi-sensor two-stage fire detection and water discharge algorithm. The objective was to detect fire at an early stage, sound an alarm and, if necessary, trigger the automatic extinguishing system before conditions would become untenable for the occupants of the room of fire origin. The fire detection system incorporated commercially available analogue addressable sensors linked to a personal computer which controlled the communications with the fire sensors, processed the detection algorithm and also triggered the discharge of water from two open head sprinklers. The sensors were installed in a 4.0 m long by 3.6 m wide by 2.4 m high room and subjected to a range of smouldering and flaming fire scenarios. The performance of the system was assessed at different detection algorithm sensitivities. The multi-sensor detection algorithm was compared with a threshold detection algorithm to examine their respective effectiveness of providing an early warning to the occupants. The false alarm rejection capabilities of the detection algorithm were also examined. A range of representative false alarm tests were conducted and the results used, in conjunction with those from the fire tests, to select the most appropriate sensitivity for the algorithm.

One Zone or Two Zones in the Room of Fire Origin During Fires? The Effects of the Air-Handling System

A two-zone model, CFAST, has been widely used in the fire re search community. However, this study indicates that the CFAST model gener ally overpredicts the upper layer temperatures in the burn room because the zonal assumption is likely to break down in the burn room. It was found that the room-averaged temperatures obtained from the CFAST model were in good agreement with the experimental results (one zone assumption in the burn room). The prediction of CO concentration is inconsistent. The CFAST model tends to overestimate CO concentration when the air-handling system is in op eration, and to underestimate CO when the system is off.

Smoke spread experiment in a multi-storey building and computer modelling

The CESARE-SMOKE model is a network model which can be used to estimate smoke spread in a multi-storey building when subjected to fire. The model calculates time-dependent temperature and species concentrations at locations remote from the room of fire origin. Spatial variation of physical parameters in a single enclosure with large aspect ratio can also be estimated. This paper describes a series of full-scale fire experiments that were designed to investigate the validity of the model. The experiments, involving steady state burning rates and a number of ventilation conditions, were conducted in a four-storey building. Temperature, pressure, flow velocity, smoke density and species concentrations were measured in various parts of the building. The chimney effect and its influence on temperature distribution in a stair shaft were observed. Comparisons are made between the experimental results and the model predictions. The experimental results are also compared with the predictions of the CFAST two-zone model. Suggestions are made for further improvements to the network model.

Fire-Plume-Generated Ceiling Jet Characteristics and Convective Heat Transfer to Ceiling and Wall Surfaces in a Two-Layer Fire Environment: Uniform Temperature Geiling and Walls

This work presents a model to predict the instantaneous rate of convective heat transfer from fire plume gases to the overhead ceiling surface in a room of fire origin. The room is assumed to be a rectangular parallelepiped and, at times of interest, ceiling temperatures are simulated as being uniform. Also presented is an estimate of the convective heat transfer, due to ceiling-jet-driven wall flows, to both the upper and lower portions of the walls. The effect on the heat transfer of the location of the fire within the room is taken into account. Finally presented is a model of the velocity and temperature distributions in the ceiling jet.The model equations were used to develop an algorithm and associated modular computer subroutine to carry out the indicated heat transfer calculations. The subroutine is written in FORTRAN 77 and called CEILHT. The algorithm and subroutine are suitable for use in two-layer zone-type compartment fire model computer codes. The subroutine was tested for a variety of fire environments involving a 107 W fire in a 8m × 8m × 4m high enclosure. While the calculated results were plausible, it is important to point out that CEILHT simulations have not been exprerimentally validated.

The development of a new small-scale smoke toxicity test method and its comparison with real-scale fire tests

A comprehensive methodology has been developed for obtaining and using smoke toxicity data for fire hazard analysis. This bench-scale method can simulate diverse fire conditions and identify extremely toxic smoke under both pre- and post-flashover conditions. However, incidence data show that most of the fire deaths in the U.S. occur outside the room of fire origin from smoke and toxic gases that are generated from a fire under post-flashover conditions. Therefore, the most relevant real-scale combustion conditions to simulate in the bench-scale apparatus would be the post-flashover conditions which are achieved by using radiant heat, a high heat flux, and correcting the bench-scale carbon monoxide (CO) results to agree with CO yields observed in real-scale post-flashover fires. The number of test animals (Fischer 344 male rats) is minimized by using the N-Gas Model to estimate the LC 50 value from the chemical analysis of the smoke. The current N-Gas Model predicts the toxicity of complex fire gas mixtures based on a large data base of experimental results of individual and mixed gases that include CO, CO2, reduced O2, HCN, HCl, HBr, and NO X. The prediction is checked with a small number of animal tests and an approximate LC 50 value is determined. The bench-scale results have been validated with full-scale room wall burns of a limited number of materials of widely differing characteristics chosen to challenge the system. The toxic potency values are assessed to determine if the smoke from a material or product is unusually or extremely toxic and can then be used in computations of fire hazard.

Protecting fire fighters exposed in room fires, part 2: Performance of turnout coat materials under actual fire conditions

Seven experimental fires varying in fire load were conducted in a simulated townhouse. Specimens of various current fire fighters turnout coat materials were exposed in the room of fire origin. The time at which conditions would become untenable for the fire fighter due to pain, as well as the time to second degree burn, were calculated. These times ranked the coat specimens in roughly the same order as the “Thermal Protection Performance” measured according to NFPA 1971–1986, especially if the heat in the room developed rapidly.

Analysing far field effects

Conditions in areas of the building distant from the room of fire origin are of importance in assessing the risk to building occupants evacuating the building. Whereas any solution is approximate in nature, this paper describes a useful method for engineering purposes. Using the method described, the concentration of combustion products in each space can be determined to predict exposure levels and time of detector actuation. A time-integrated dose can be calculated for each building occupant based on their length of travel time from each room to the exit to evaluate the level of risk.

The Effects Of Fire Products On Excape Capability In Primates And Human Fire Victims

Animal studies of incapacitation by thermal decomposition products indicate that the common asphyxiant gases, CO, Ha, low 02 and C02 are almost certainly responsible for the severe narcosis and death of fire victims overcome by smoke. Eye and upper respiratory tract irritation also probably impair escape capability but to an unknown degree. Time to narcotic incapacitation in man should be predictable if the fire profile in terms of the above gases is known. Incapacitation of victims of smoldering and post-flashover fires can be explained in these terms, but victims should be able to escape from early flaming fires. It is suggested that the high incidence of victims in the room of fire origin may be partly due to sleeping victims being intoxicated by CO during the smoldering phase