Search

Suspended false ceilings are commonly installed as a new interior design feature in modern buildings of the Far East. Different shapes, profiles, materials and installation methods were adopted. There are fire safety concerns on extending the activation time and disturbing the water spray pattern of sprinkler systems. Ceilings with timber products might also be ignited. It is necessary to study the differences in thermal environment of a fire in rooms with and without suspended ceiling features.

This paper gives an overview of the tunnel fire research, both experimental and theoretical work with the exception of computer modelling. The overview shows that the critical velocity for longitudinal flow in a tunnel is the single most well investigated fire phenomenon found in the tunnel fire research literature. This knowledge has reached a high level but there are still some areas that need to be investigated further. For example, very little work has been done on backlayering of smoke upstream a fire and cross-sectional effects on heat release rates, temperatures, flame lengths, fire spread and toxic conditions. Extensive work using model scale tunnels has contributed with new information and clarified many phenomena but the lack of good large scale experimental data is and will be a key issue in near future. This concerns mainly the correlation between heat release rate and maximum ceiling temperatures, the influence of ventilation on maximum heat release rate and fire growth rate and fire spread in and between vehicles. The extensive theoretical work which has been conducted concerning the effects of ventilation on heat release rates needs to be further investigated in large scale tests.

Dry-pipe sprinkler systems are commonly used when the ambient temperature of a protected space is below freezing temperature of water. Because the degree of fire spread prior to sprinkler actuation is greater than that of the wet system in comparable circumstances, a greater coverage area is often required in a drysystem than that of a wet system. In addition, the dry system also requires the water delivery time to the most remote sprinkler be within a certain time limit. Dry-pipe ceiling-sprinkler restriction imposed by NFPA 13 for the protection of Class 2 materials in rack-storage higher than 7.6-m under 12-m ceiling is a maximum 30-seconds water delivery time with a 4-heads-open assumption. An in-house computer program developed to estimate water delay times in dry-pipe systems has been extensively used at FM Global for the last 15 years to address the water delivery time requirement mentioned above for industrial freezers. This paper describes how the program was developed and how the 30-seconds water-delivery time requirement could be met by choosing proper operating conditions through numerous real design cases. The examples showed that by adjusting many operating control parameters, most of the system could meet the 30-seconds water delivery time restriction without making substantial alteration in system configurations. The case study also shows that the air trip time linearly increases with the system volumes as anticipated. The water transit time also increases with the system volume in general, however, the dependence was more complex, which indicates that the system configuration plays an important role in the transit time in dry-pipe systems. Overall, the case study shows that the program had enabled the system design to be much more flexible and cost effective.

Specialized buildings such as mental health facilities present unique challenges for fire safety design, as occupants typically should not be evacuated, unless directly threatened by the effects of fire. The New Zealand ‘deemed to satisfy’ solutions address this with a mandatory minimum requirement for early warning smoke detection and sprinkler suppression systems in buildings with this occupancy, installed in accordance with New Zealand Standards. However, in some instances, the solutions in the Standards are in conflict with clinical requirements to protect patients from (self-) harm. One example is point-type smoke detectors, which should be installed below the ceiling to be compliant with the Standard, but must be located in a protected recess above the ceiling to meet clinical needs. This case study outlines the performance based design of an aspirated recessed point type smoke detection system in the bedrooms of a secure wing in a mental health facility, operated by one of the largest district health boards in New Zealand. The system was purpose designed to cater for the clinical requirements of the health board. The performance based solution combines the location identification ability of point type analogue addressable detection systems with the unobtrusive installation of aspirating systems. The system consists of fully recessed proprietary analogue addressable point type smoke detectors that are combined with a small aspirating system. The system was successfully tested in comparison with ceiling mounted point type smoke detectors and was accepted by all stakeholders as a specialized engineered solution giving performance equivalent to that of a Standard compliant system.

Due to the ceiling jet phenomenon, smoke above a fire source has a natural tendency to spread under the ceiling in all directions, until a barrier is reached. The present study focuses on smoke control, rather than smoke clearance, in large closed car parks. A particular situation is that the ceiling height is much lower than the horizontal car park dimensions. Also, flame heights can be in the same order of magnitude as the ceiling height, so that flames can penetrate into the smoke layer under the ceiling near the fire source. Smoke control in case of fire in large car parks can be established by horizontal mechanical ventilation. A ‘critical ventilation velocity’ exists, for which no smoke backlayering occurs, i.e. the car park is maintained smoke-free at one side of the fire source. In many cases, however, backlayering can be allowed to a certain distance. We analyse the results from a large series of CFD-simulations, used as numerical experiments, and illustrate that there is a relation between the horizontal ventilation velocity and the backlayering distance. The backlayering distance varies linearly with the difference between the critical ventilation velocity and the actual ventilation velocity of the incoming fresh air. We perform a parameter study with variation of heat release rate per unit area, fire source area, car park width and car park height. We show that the coefficient in the mentioned linear relationship is independent of the fire source area, the car park height and the car park width, but increases with decreasing heat release rate per unit area. We compare the results for the critical ventilation velocity in car parks to results obtained in tunnel fires. We confirm the observations that the critical ventilation velocity increases with fire source area and heat release rate per unit area, as well as a small influence of the car park width. We observe an increase of the critical ventilation velocity with increasing car park height. Finally, we point out that care must be taken when a smoke control system design is based on volume flow rates, calculated from cold inlet flow velocities, as differences between extraction velocities and incoming air velocities can be substantial.

By using Alpert's correlations for a ceiling jet in a steady fire, the heat release rate of the fire source can be predicted based on the operation of the fixed-temperature heat detector or sprinkler's heat sensitive device. However, as a fire grows with time in the early stage, the time until hot gases induced by a fire reach the sensor is different in proportion to the radial position, and this should be considered in order to predict the precise heat release rate based on the ceiling jet temperature. In this study, correlations for ceiling jet temperature and travelling time of hot gases are derived by dimensional analysis. The values of the coefficients in the derived correlations were deduced from the comparison with experiments. It is concluded that the travelling time of hot gases can be predicted by treating the upward flow along the plume axis and ceiling jet spreading radially as a continuous flow and that heat release rate could be predicted more precisely by considering this travelling time.

A full-scale fire experiment has been conducted on a typical Australian passenger train. In this experiment a train fire was allowed to become fully developed involving all combustible materials within the train. This paper focuses on the results of the fully developed fire. The experiment was conducted outside rather than in a tunnel. Measurements included temperatures, vent flows, heat flux and gas analysis. Observations were recorded. It was found that ceiling and upper wall linings are more critical for fire spread than seats and lower wall linings. The ignition source consisted of 1 kg of crumpled newspaper, the equivalent of a Saturday Melbourne newspaper, located on the floor, beneath a seat in one corner of the carriage interior. The fully developed fire went to flashover 140 s after ignition and spread inside the vehicle very rapidly, spreading to have involved all fitted materials by 175 s. This highlighted the very short evacuation time available for such an event. From 150 s large plumes of flame flowed out the side doors and a very high production of smoke was observed. After flashover the peak heat release rate was ventilation controlled. From this it is concluded that many common methods of estimating train fire heat release rate are not valid and that further research into ventilation of train fires is required. This experiment provides unique full scale data for a flashover fire on a furnished suburban rail carriage.

Ceiling jet dynamics are quantitatively characterized using the salt-water modeling technique. In this study, salt-water is introduced into fresh water to create an axisymmetric impinging plume and the associated stratified wall jet. This configuration models the canonical ceiling jet flow that results from impinging fire plumes. The saltwater modeling analogy is demonstrated through rigorous scaling of the governing equations and comparison of the resulting fire and salt-water source-based dimensionless quantities. With appropriate scaling, the measured concentrations in the salt-water model can be directly compared with temperatures in the fire configuration. Measurements of the mixing and dispersion in the ceiling jet region are performed using Planar Laser Induced Fluorescence (PLIF). These measurements provide quantitative visualization of the turbulent flow structure in addition to mean concentration profiles. Ceiling layer thicknesses, peak profile values, and profile shapes along the ceiling compare favorably with ceiling jet theory and data from actual fire experiments. Furthermore, turbulent flow details are revealed through the laser sheet visualization providing insight into the flow behavior and providing quantitative data for CFD code validation.

In this paper, an approach for modeling ceiling flame spread beneath a combustible board is developed. The presented model consists of a one-dimensional flame spread model coupled with a one-dimensional pyrolysis model. Firstly, the pyrolysis model is validated against the experimental data from the literature. In addition, the existing experimental data (the ceiling flame spread beneath medium density fibreboard (MDF)) are used for comparison to validate the numerical model. The results obtained from numerical simulations using the presented model are consistent with the experimental tests.

Three full scale tests were conducted in a road tunnel to study the smoke spread with different fire sizes and wind speed conditions. The smoke temperature under the ceiling, the smoke layer height distribution and the travel of the smoke front in a 1000 m long domain along the road tunnel were measured. Results showed that wind speed had much influence on the spread of smoke in the tunnel. When wind speed was such low as less than 1 m/s, a smoke layer could form and stabilize all along the tunnel. But when the wind speed was such high as more than 2 m/s, smoke layer could only be maintained in a distance of about 400 m in the downstream. The slowdown of the traveling of the smoke front in the downstream along the tunnel was more obvious when the wind speed was smaller. All these full scale data presented here can be used for further study on the verification or improvement of existing fire models for enhancing their applicability to such long tunnels.

Five large-scale fire tests were conducted to determine sprinkler protection requirements for non-storage occupancies with floor-to-ceiling clearance up to 18.3 m. Examples of high-ceiling, non-storage occupancies are atrium spaces, movie theaters/studios, auditoriums, and some selected manufacturing facilities. The fire tests were conducted at a 18.3-m high test site using fuel arrays that were designed to simulate ordinary hazard fire scenarios. Sprinkler protection parameters and fuel arrangements were varied in the tests. The tests showed that:1) the sprinklers would provide adequate protection for these occupancies despite a clearance as high as 16.6 m from the top of the fuel stacks to the ceiling, 2) protection based on a 12-mm/min discharge density over a 465-m demand area was judged adequate for fire hazards equivalent to a FMRC Class 3 Commodity, 3) protection based on a 6-mm/min discharge density over a 232-mdemand area was adequate for fire hazards up to a Class 2 Commodity, 4) protection based on QR-ELO sprinklers delivering a 18-mm/min discharge density over a 232-mdemand area would provide adequate protection for high-ceiling occupancies exposed to a limited amount of plastic materials. Sprinkler skipping, extended sprinkler spacing, and protection of an occupancy with a ceiling higher than 18.3 m remain as subjects needing further study.

The flammability of interior finish materials for many applications is regulated using the ISO 9705 large-scale room corner fire test. To aid designers in developing new materials, a fire growth model has been developed to predict material performance in the ISO 9705 test using small-scale test data from ASTM E1354 cone calorimeter. The fire growth model includes a flame spread model linked with a two zone compartment fire model, CFAST Version 3.1.2. At a user selected time interval, the flame spread model uses the gas temperature from CFAST to predict the heat release rate of the fire at that time interval, and then provides CFAST with a new heat release rate to predict conditions during the next time step. The flame spread model is an improved version of the flat wall flame spread model previously developed for the U.S. Navy. The model is capable of predicting flame spread in a variety of configurations including a flat wall, a corner with a ceiling, flat wall with a ceiling, unconfined ceiling, and parallel walls. The fire growth model was used to predict the heat release rate and smoke production rate measured in eight ISO 9705 room corner fire tests on composite materials used in marine applications.

An experimental study of liquid pool fires was undertaken in the corner and centre fire geometries. An Industrial Methylated Spirits fuel placed in square trays and elevated from the floor was used in the study. The fuel trays ranged in size from a 0.2m tray which was used in a 1/3 scale test enclosure to 0.5-1.0m trays used in an ISO sized room. Measured, well mixed ceiling gas temperatures and energy release rates were correlated with two dimensionless groups as used in the well known McCaffrey, Quintiere, Harkleroad (MQH) correlation. An initial interrogation of the MQH correlation suggests that the modification to the MQH correlation suggested by Mowrer and Williamson for the corner fire geometry is satisfactory. In the case of the centre room fires, correlation of the data suggested a proportionality factor CT which was at the upper limit of the data correlation shown in the original MQH work. This result may be attributable to intermittent flames approaching the ceiling for these tests where quality data was only available tests with the doorway at half width and for large fuel trays. The paper addresses key factors that need further investigation for validating and refining the MQH correlation(s).

The Actual Delivered Density (ADD) of a standard sprinkler and a conventional sprinkler for rack-storage fires has been studied experimentally using an ADD apparatus equipped with a fire plume simulator. The variables examined included sprinkler discharge rates (76-212 L/min), heat release rates of the fire (0, 500, 1000, 1500 and 2000 kW), ceiling clearances (3.05, 4.57 and 6.10 m), and ignition locations (centered below one sprinkler and below four sprinklers). The sprinkler spacing was maintained at 3.05 m for all the tests. The results of the measurements indicate that the ADD decreased as the ceiling clearance is increased from 3.05 m to 6.10 m. The ADD data have been correlated satisfactorily using two parameters. One parameter corresponds to a drop size ratio and the other is the ratio of the spray momentum to the momentum of the fire plume. It is demonstrated that the ADD can be used to interpret the performance of the standard and conventional sprinklers in the large-scale rack storage fire tests conducted.

Air entrainment ratio to mechanical ceiling vent was investigated by model scale experiments for quiescent two-layers environment. For various combinations of venting velocity and smoke layer temperature, critical smoke layer thickness for onset of entrainment was identified by eye-observation. Air entrainment ratio was measured by the change of carbon dioxide concentration in smoke layer (before entrainment) and in exhaust duct (after entrainment). By summarizing the measured results, the followings were clarified. 1) The critical thickness for onset of entrainment depends on smoke layer temperature and largely on smoke layer thickness. When the smoke layer is thick, large venting velocity is needed to cause air entrainment. In this condition, flow into vent opening can be approximated by potential flow to point sink. As the smoke layer thickness is decreased, relatively small venting velocity can cause air entrainment. In this condition, flow pattern can be approximated by potential flow to line sink or to plane sink depending on aspect ratio. 2) Even at the critical condition determined by eye-observation, certain amount of air is entrained. 3) Beyond the critical condition, air entrainment ratio can be approximated by the fraction of actual smoke layer thickness to critical smoke layer thickness for onset of visible air entrainment.

Measurements of the heating condition of a steel beam installed beneath a ceiling and exposed to a localized fire source are made on a real-scale experiment. The data of thermal response obtained from the experiments are compared with previous small-scale experiments. The effects of the smoke layer which influences upon the heating condition of the beam are investigated through the smoke experiments setting the smoke protection soffits to the same experimental equipment. FDM-based calculation is demonstrated using the average temperature of the smoke layer for the boundary conditions to predict the thermal response of the beam. Applicability of the approximated temperature of the smoke layer is examined by comparing the numerical results of the temperature with those obtained through the experiment.

Experimental heat transfer and temperature correlations are presented for a steel beam installed beneath a ceiling when exposed to a localized fire source. The heat flux distribution on every part of the beam is formulated as a function of flame length and the distance from the fire source. A specially written finite volume code CV-FEM, as well as the general-purpose finite element code ANSYS were used for the numerical simulation. Experimental values of heat fluxes were applied as boundary conditions for the surfaces exposed to fire. The results of the three-dimensional transient thermal analysis obtained are compared with the experimental data. The program CV-FEM was found to be very effective for this type of problem. The experimental correlations obtained and numerical procedure developed can be used to predict the heating mechanism and thermal response of practical building members exposed to a localized fire.

A series of seven large-scale rack storage f i e tests was conducted, using four ESFR sprinkler models, to determine the required sprinkler spray characteristics for achieving effective protection of rack storages of the FM standard plastic commodity up to 10.8 in high in a 12.2 m high warehouse. AU four models have a nominal K factor of 0.34 ~/s/(k~a)", and the sprinkler discharge pressure was maintained at 517 kPa. The sprinkler spacing was 3.05 m x 3.05 m. The test variables include storage heightlceiling clearance, ignition location and sprmkler models. The sprays of the sprinkler models used in the fire tests were characterized by their drop size distribution, center-core thrust force, and water distribution under no-fire condition. For ESFR sprinkler protection, the effect of drop size distribution was demonstrated to be unimportant through the fire tests. For the case with ignition directly over a sprinkler, the spray center-core thrust force and the water flux under no-fue condition over the top surface of a two pallet-load by two pallet-load fuel array directly underneath the sprinkler have been shown to be critical for achieving f i e suppression. A minimum centercore thrust force of 101.3 ~ / m ' measured at 1.77 beneath the sprinkler deflector, and a minimum water flux of 0.614 l/s/m2 measured over a 2.15 m x 2.15 m area 4.42 m beneath the ceiling directly under the sprinkler have been found to be necessary for achieving fire suppression. For the case with ignition centered below two sprinklers and with 10.8 m storage height / 1.77 m ceiling clearance, only the water flux under no-fire condition over the fuel array top was shown to be critical. A measured water flux of 0.667 0/s/m2 over a 2.15 m x 2.15 m area, centered below the two sprinklers, 1.77 beneath the ceiling, was found to be sufficient for achieving fire suppression.

Detailed measurements of velocity and temperature in a primary channel of a beamed ceiling are presented in this paper as well as flow spillage under the beams. The data has been used to validate the empirical relation developed by Delichatsios and modify it for use in a more general situation. The primary focus has been to characterize the flow for beam depths that result in a ceiling jet to be in the transition between smooth ceiling jet flow and a corridor flow. As a result of this study, a modified empirical relation to calculate the ceiling jet temperature in a primary channel based on the ceiling heat transfer and the beam to ceiling height ratio has been presented here. The results tend to show that primary channel flow approaches a corridor flow for beam depth higher than 15 % to 20% of the fire to ceiling height.

The designers of tunnels must provide comfortable conditions for occupants. This necessitates particularly the development of ventilation equipments well suited for routine operation but also efficient in the case of accidental fires while a t the same time offering the possibility of control. A computer model for simulation of fire growth and smoke back flow phenomenon countering the effect of ventilation is described. I t permits one to predict the length of the reverse layer under a ceiling as a function of two main parameters : ventilation speed and rate of heat release of the fire. Special attention is devoted to the description of the fire source with consideration of the interaction between flow and the chemical reaction. The validation of the model against experimental results, obtained previously on a small-scale prototype, appears satisfying. An application to the Paris metro tunnels is also presented. The validity of the predictive results is infered from the similarity between small-scale and real situation based on a scaling procedure.

Acoustic emission (AE) has been shown to be a viable concept for the early indication of an open flame impinging on various structural materials. To assess its effectiveness in a more realistic environment, experiments have been performed in a 2.4 m cubical room constructed of gypsum board and wood. AE transducers were mounted on top of a ceiling joist and on a wall stud. The threats examined were a natural gas fire producing a thermal load up to 125 kW, and a charring condition achieved by attaching a 550 W electrical heater to a wall stud. A signal discernable above the background was recorded from at least one AE sensor in six of nine situations. In each case, measurable acoustic emission occurred before a noticeable increase in voltage from the thermocouple mounted adjacent to the AE sensor. The conclusion is that AE emission appears to be sufficiently sensitive to detect two particular threats, and that an overheated condition in a wall or ceiling can be detected if it is not more than 3 m from the transducer. Additional experiments are required to identify signals that are likely to complicate the differentiation between a false and a true fire event.

The steady fire-produced ceiling jet in an open ended corridor is examined with a simplified "top hat" theory. At a corridor open end, the hot fluid accelerates upward producing a Richardson Number equal to I for tranquil flow as the flow control. Friction satisfies this condition by upstream waves with a hydraulic jump, if necessary. Entrainment has qualitatively the same result, but with quantitative differences. Heat transfer at low friction causes the Richardson Number and depth to rise. The manner of adjustment to Ri = I at an open end needs further study.

In the context of the relationship between the fire safety engineer and the fire scientist a few scientific and engineering problems are discussed. Some comments are made about engineering theories of plumes and flames and a dimensionless correlation of the length of flames from a corner source under a ceiling is presented. Fire safety engineers may now be able to exploit a thermal theory of upward flame spread using data obtained by recently developedflammabili ty tes t s .

Previously, we have conducted measurements of heat flux and temperature distribution of the H-shape beam installed beneath a ceiling and exposed to a localized fire source. From the results ofthe experiment, heat flux distribution on every part of the beam was formulated. In this paper ,the temperature distributions were computed by the finite different method using experimental heat flux data and compared with results of the experiments to evaluate the applicability of the analytical technique The result shows that when compared with the experimental data, the temperature distribution on the axial direction of the member can be predicted with about 15% error in the range ofO.5m from the stagnation point, and with20% error or less in other positions. In order that this model may be applied to an actual building, we assume 1\\"0 cases: one is that the temperature is calculated with the experimental data of heat flux approximated by a functional equation, and the other is a case that the experimental data is input in the model directly as mentioned above: and these 1\\"0 cases are compared with each other in their accuracy. In the same scheme, several kinds of metal material properties data were used in the calculation to know the heating conditions which may achieve the allowable range of temperature required in the current regulation.

A series of fire tests was conducted under a smooth ceiling to investigate the ceiling gas flow as affected by ceiling slope, convective heat release rate of the fire and clearance between the fuel top surface and the ceiling. Besides a horizontal ceiling reference, three ceiling slopes were investigated: 10°, 20° and 30°. Pool fires were used as fire sources. Two pool diameters, two different fuels (heptane and methanol) and three ceiling clearances were used. In each test, measurements were made of ceiling gas temperatures, ceiling gas velocities, and fuel mass loss. Empirical correlations for the near-maximum gas velocity and excess temperature of the ceiling flow along the steepest run were established in terms of ceiling slope, radius from the point of intersection of the ceiling with the pool centerline, and characteristics of the undeflected plume at the ceiling level. The ceiling slope had a more pronounced effect on velocity variation along the steepest run than on temperature variation. In the upward direction, the rate of velocity decr-ease with radius was reduced significantly as the ceiling slope increased. In the downward direction, at a certain distance from the pool cent.e r-I ine, the flow separated from the ce il ing and turned upward. The larger the ce i I ing slope, the sooner' the turning occurred. Fur thermor-e , the rate at which gas temperature approached ambient in the downward direction increased wi th ceil ing slope, while the temperature decrease in the upward direction was not much affected by change of ceiling slope.

This paper describes the nnmerical analysis of ceiling jets relevant to the "T" pattern flame which accelerates the fire growth due to a flame burning upward along a corner, using a three-dimensional field model. It vas found in calculations that ceiling jets split into two directions along ceiling-wall intersections when a heat source is located at a marked distance from a corner. Isotherms, velocity vectors and isobaric contours of the split ceiling jet showed the configulation similar to the "T" pattern in the experiments of Williamson et al. The "T"-shaped flow was investigated using "open" and "closed" type fire rooms. Further , it was found that the distance between the corner and heat source plays an important role in forming the "T" pattern and that the temperatures and pressures at the ceiling corner oscillate regularly.

JUAN COlOMBAS Department Fluid Mechanics E.T.S. Ingenieros Industriales Universidad Politecnica de Madrid C/Jose Gutierrez Abascal 2, 28006 Madrid, Spain Some simplifications have been introduced in the classical models to describe the evolution of fires. They have been applied to single room compartments, obtaining a significant reduction in the computer time required. The heat equation is solved in solid walls and ceiling by using a global energy conservation equation which utilizes the whole history, from the beginning of the fire, of the temperature at the hot surfaces of the walls. An algorithm has been used to avoid the storage of all the va! ues of this surface temperature. Another simplification consists in a sys tematic treatment of the radiative heat transfer between the different elements, which is based on the assumption that they form a closed surface and that the energies reflected from and transmited through the flame are small compared to the energy that it emits; this assumption may be acceptable in many cases of interest. A computer code has been developed to predict the evolution of fires, including the above mentioned sim plifications; although a more complete validation of the code is necessary, preliminary comparisons with other codes and experiments have been satisfactory.

The Harvard multi-room fire simulation, has been used to simulate a fire in a single -level, 8 room complex. The model has been enriched to simulate forced ventilation and re-dimensioned to allow up to 10 rooms and 20 vents. No experimental, full-scale fire data is available against which to compare the predictions. Comparative results are provided which illustrate the effect of no forced ventilation and forced ventilation providing up to six air changes per hour. The forced ventilation supplied air to rooms opening off a corridor and extracted it from the corridor ceiling. For one large room, supply was at floor level and extraction from the ceiling. With this arrangement, the spread of fire gases was inhibited and tenability times increased by the forced ventilation. With another supply and exhaust arrangement the reverse might have been expected.

Thirty-two flaming-started fire tests were conducted in a test room to determine the effect of cathedral (sloped) and/or beamed ceiling construction on fast-response residential sprinkler performance. The fire tests were conducted with the ceiling being either horizontal or pitched to a 14° slope. Beams of two different depths were employed. Test results indicate that sloped and/or beamed ceilings represent a serious challenge to the fire protection afforded by fast-response residential sprinklers. However, with reasonable modifications to the installation standards and the water supply, fire control equivalent to that observed under smooth horizontal ceilings may be obtained.

In this paper the calculation of critical events in a fire situation defined as time for smoke logging and flashover is shown using two different fire models. Two models were used, a revised DFPA version of the simple model ASETB and the more complex model DSLAYV. Both of these are single-room models. They assume near-floor-elevation leakage and they have a capability for simulating the effect of ceiling ventilation to the outside ambient. In using the two models, the difference in calculated times is never larger than 15 % showing that ASETB works well as an engineering tool. The error which occurs when you are using wrong description of the fire growth is much larger.

Data acquired during tests involving full-scale, sprinklered, compartment fires are presented and analyzed. Attention is focused on key features of the typical sprinkler link deployment/response problem. It is found that the elevated-temperature, smoke layer which develops inevitably in compartment fires can have a major impact on the thermal response of sprinkler links. It is shown that traditionally accepted methods of predicting sprinkler link response which do not account for this upper layer can be totally inadequate. Link response predictions used here involve a method of calculation which does take account of the smoke layer. Favorable comparisons between predictions and experiment are obtained and further validation of the method is recommended. Finally, it is found that sprinkler link-to-ceiling spacing can have a significant effect on the thermal response of links and it is recommended that a method which accounts for this effect be developed and validated.

Several fluid dynamic processes which play important roles in the development of accidental fires in structures are discussed. They include a review of information concerning the characteristic flow regimes of fire plumes and the properties of the flow in these regimes, and a brief review of flow through openings and in ceiling jets. Factors which lead to the development of thermal stratification in ceiling layers are also discussed.

A series of 3 freeburn and 22 sprinklered fire tests was conducted to investigate cooling in room fires by sprinkler spray. The tests were conducted in a 3.66 m x 7.32 m x 2.44 m high test room, which had a 1.22 m x 2.44 m high door opening centered in one of the 3.66 m walls. The fire source was a spray fire with constant heptane flow rate, located opposite the room opening. In each test, only one sprinkler was installed at the ceiling. Three geometrically similar sprinklers with nozzle diameters of 11.1 mm, 8.36 mm, and 6.94 mm were tested. The gas temperatures inside the test room were measured at selected locations. In addition, the convective heat flux leaving the door opening and the total heat release rate of the fire were measured with a fire products collector. The heat loss rate to the walls and ceiling was measured, as well as radiative heat loss through the opening. Empirical correlations for the bulk gas temperature of the hot gas flowing out from the door opening were established for both freeburn and sprinklered fire tests conducted in this study. Used with the previously established spray cooling correlations [2], the new correlations can predict the bulk gas temperature of the hot gas at the door opening for freeburn and sprinklered room fires.

We investigated the effect of ventilation rate, ventilation configuration, fire elevation, and the presence of a plenum (suspended ceiling) on the fire compartment temperatures during forced ventilated methane gas fires (100-400 kW). We found that with low air-inlet positions, fires with ventilation rates greater than 2 to 3 times the stoichiometrically required air (referred to here as well-ventilated fires) produce two-layer temperature profiles; fires with a lower ventilation rate (under-ventilated fires) produce single-layer profiles with a temperature gradient. Higher temperatures throughout the enclosure are seen in underventilated fires as compared to well-ventilated fires. We observed that high air-inlet locations perturb the two-layer temperature profile of the well-ventilated fire, cooling the upper layer and heating the lower layer. For underventilated fires, high air-inlet locations lower temperatures in the enclosure but do not perturb the profile shape. Elevated fires and fires in a compartment with a plenum were seen to behave similarly for the same distance from fire base to ceiling, producing hotter layers the shorter the distance. 9 refs., 13 figs.

An algorithm is developed to predict the thermal response of aircraft ceiling materials during a post-crash fire scenario. The scenario involves an aircraft's emergency exit doorway which opens onto the flames of a fuel-spill fire which engulfs the fuselage. Data of near-ceiling temperatures acquired during fullscale, post-crash test simulations provide indirect validation of the algorithm. The post-crash time-to-ceiling-ignition is proposed as a measure of cabin fire safety. This measure would be used as a surrogate for the post-crash time available for passengers to safely evacuate the cabin. In this sense, the algorithm is exercised in an example evaluation of the fire safety of a candidate honeycomb ceiling material used together in cabin systems involving polyurethane cushion seating.