NISTIR 7079 

Effect of Beamed, Sloped, and Sloped 

Beamed Ceilings on the Activation Time of a 

Residential Sprinkler 

Robert L. Vettori 

Building and Fire Research Laboratory 

National Institute of Standards and Technology

Gaithersburg, MD 20899-8641 

Sponsored by 

Department of Homeland Security

Federal Emergency Management Agency 

United States Fire Administration
NISTIR 7079 

Effect of Beamed, Sloped, and Sloped 

Beamed Ceilings on the Activation Time of a 

Residential Sprinkler 

Robert L. Vettori 

Fire Research Division 

Building and Fire Research Laboratory 

National Institute of Standards and Technology

Gaithersburg, MD 20899 

December 2003 

Department of Homeland Security

Tom Ridge, Secretary

Federal Emergency Management 

Agency 

Michael D. Brown, Under Secretary of 

Emergency Preparedness and Response 

U.S. Fire Administration 

R. David Paulison, Administrator

U.S. Department of Commerce

Donald L. Evans, Secretary

Technology Administration

Phillip J. Bond, Under Secretary for Technology

National Institute of Standards and Technology

Arden L. Bement, Jr., Director
Table of Contents 

List of Tables ................................................................................................................................. iv 

List of Figures................................................................................................................................ vi 

Abstract........................................................................................................................................... 1 

1 Introduction......................................................................................................................... 2 

2 Experimental Configuration................................................................................................ 4 

2.1 Instrumentation ................................................................................................................... 5 

2.2 Sprinklers............................................................................................................................ 5 

2.3 Gas Burner .......................................................................................................................... 5 

3 Location of Fire................................................................................................................... 6 

4 Experimental Results.......................................................................................................... 7

4.1 Effect of Beamed, Sloped, and Sloped Beamed Ceilings on Sprinkler Activation Times. 7 

4.2 Effect of Beamed, Sloped, and Sloped Beamed Ceilings on Temperatures....................... 7 

5 Computer Modeling............................................................................................................ 7 

5.1 Results of Computer Modeling........................................................................................... 9 

6 Uncertainty Analysis........................................................................................................... 9 

7 Discussion......................................................................................................................... 10 

7.1 Discussion of Experimental Results................................................................................. 10 

7.2 Discussion of Computer Modeling ................................................................................... 12 

7.2.1 Sprinkler Activation Calculations..................................................................................... 13 

8 Conclusions....................................................................................................................... 15 

9 Acknowledgements........................................................................................................... 16

10 References......................................................................................................................... 37 

iii
List of Tables 

Table 1 Effect on sprinklers 1 and 2 as the ceiling slope is increased to 13° and then 24°........ 4 

Table 2 Effect on sprinklers 3 and 4 as the ceiling slope is increased to 13° and then 24°........ 5 

Table 3 Grid resolution for various ceiling heights..................................................................... 8 

Table 4 Uncertainty in experimental data ................................................................................. 10 

Table 5 Percent difference between FDS and average measured times.................................... 12 

Table 6 Sprinkler activation times for horizontal smooth and horizontal beamed ceilings...... 17 

Table 7 Sprinkler activation times for smooth and beamed ceilings sloped at 13° .................. 17 

Table 8 Sprinkler activation times for smooth and beamed ceilings sloped at 24° .................. 18 

Table 9 Sprinkler activation times for all smooth ceilings........................................................ 18 

Table 10 Sprinkler activation times for all beamed ceilings....................................................... 19 

Table 11 Temperature at the 1.52 m (5ft) elevation at the time of sprinkler activation for 

horizontal smooth and horizontal beamed ceilings...................................................... 19 

Table 12 Temperature at the 1.52 m (5ft) elevation at the time of sprinkler activation for 

smooth and beamed ceilings sloped at 13° .................................................................. 20 

Table 13 Temperature at the 1.52 m (5ft) elevation at the time of sprinkler activation for 

smooth and beamed ceilings sloped at 24° .................................................................. 20 

Table 14 Temperature at the 1.52 m (5 ft) elevation for all smooth ceilings.............................. 21 

Table 15 Temperature at the 1.52 m (5 ft) elevation for all beamed ceilings............................. 21 

Table 16 Comparison of experimental versus predicted activation times for the smooth 

horizontal ceiling.......................................................................................................... 22 

Table 17 Comparison of experimental versus predicted activation times for the horizontal 

beamed ceiling ............................................................................................................. 22 

Table 18 Comparison of experimental versus predicted activation times for the smooth 

ceiling sloped at 13°..................................................................................................... 23 

Table 19 Comparison of experimental versus predicted activation times for the beamed 

ceiling sloped at 13°..................................................................................................... 23 

Table 20 Comparison of experimental versus predicted activation times for the smooth 

ceiling sloped at 24°..................................................................................................... 24 

Table 21 Comparison of experimental versus predicted activation times for the beamed 

ceiling sloped at 24°..................................................................................................... 24 

Table 22 Comparison of predicted versus measured temperature at the 1.52 m (5ft) 

elevation at the time of sprinkler activation for the horizontal smooth ceiling ........... 25 

iv
Table 23 Comparison of predicted versus measured temperature at the 1.52 m (5ft) 

elevation at the time of sprinkler activation for the horizontal beamed ceiling........... 25 

Table 24 Comparison of predicted versus measured temperature at the 1.52 m (5ft) 

elevation at the time of sprinkler activation for the smooth ceiling sloped at 13°....... 26 

Table 25 Comparison of predicted versus measured temperature at the 1.52 m (5ft) 

elevation at the time of sprinkler activation for the beamed ceiling sloped at 13°...... 26 

Table 26 Comparison of predicted versus measured temperature at the 1.52 m (5ft) 

elevation at the time of sprinkler activation for the smooth ceiling sloped at 24°....... 27 

Table 27 Comparison of predicted versus measured temperature at the 1.52 m (5ft) 

elevation at the time of sprinkler activation for the beamed ceiling sloped at 24°...... 27 

v
List of Figures 

Figure 1 – Side view of a typical sloped ceiling configuration. Drawing not to scale. ............... 14 

Figure 2 – Side view of a typical sloped ceiling configuration. Drawing not to scale. ............... 14 

Figure 3 Plan view of experimental set up. ................................................................................ 28 

Figure 4 Front view of experimental set up................................................................................ 28 

Figure 5 Side view of the test room showing different elevation and angles of the ceiling....... 29 

Figure 6 View of the test room. The ceiling in this picture is sloped at 13°. The burner 

mass flow controller can be seen at the bottom of the figure along with the 

methane gas bottles. ..................................................................................................... 29 

Figure 7 Instrumentation set up for each sprinkler. All thermocouples maintained same

distance from the ceiling regardless of ceiling height except for the lowest 

thermocouple which was always maintained at a distance of 1.5 m from the floor. ... 30 

Figure 8 Gas burner placed for a corner experiment.................................................................. 30 

Figure 9 Fast, medium, and slow fire growth regions................................................................ 31 

Figure 10 Calibration data for the rectangular gas burner............................................................ 31 

Figure 11 Distance between sprinklers and burner when the burner is placed against the 

wall............................................................................................................................... 32 

Figure 12 Front view of modeled room showing doorway, beams, burner, and sprinklers. 

The burner in this scenario is in the detached position. ............................................... 32 

Figure 13 Horizontal beamed ceiling model representation showing grid in the x and y 

directions...................................................................................................................... 33 

Figure 14 Side view of FDS representation of smooth sloped ceiling sloped at 13°. In this 

scenario the burner is placed in the corner. The four red squares on the ceiling 

represent sprinklers. ..................................................................................................... 33 

Figure 15 Side view of FDS model representation of beamed sloped ceiling sloped at 24°. 

The two beams are shown in red and the two small red dots on the ceiling 

represent sprinklers 1 and 4. ........................................................................................ 34 

Figure 16 Increase in ceiling jet temperature for sprinklers 1 and 4 for experiment number 

25, smooth ceiling sloped at 13° and burner in the detached position......................... 34 

Figure 17 Ceiling jet velocity at sprinklers 1 and 4 for experiment number 25, smooth 

ceiling sloped at 13° and the burner in the detached position...................................... 35 

Figure 18 FDS prediction for sprinklers 1 and 4 ceiling jet temperature, smooth ceiling 

sloped at 13° and burner in the detached position. ...................................................... 35 

Figure 19 FDS prediction for sprinklers 1 and 4 ceiling jet velocities, smooth ceiling sloped 

at 13° and burner in the detached position................................................................... 36 

vi
Effect of Beamed, Sloped, and Sloped Beamed Ceilings on the Activation 

Time of a Residential Sprinkler 

Robert L. Vettori 

Abstract 

A series of 72 experiments was conducted to compare the effects of beamed, sloped, and sloped 

beamed ceilings on the activation times of a quick response residential pendent sprinkler. Six 

different geometries were studied. The geometries included a smooth horizontal ceiling, a 

horizontal beamed ceiling, a smooth ceiling with a slope of 13°, a beamed ceiling with a slope of

13°, a smooth ceiling with a slope of 24°, and a beamed ceiling with a slope of 24°. For each 

configuration, the fire source, a computer controlled methane gas burner, was placed in three 

different locations. Additionally, for each burner location, the flow of methane gas to the burner 

was supplied in such a way as to give two different fire growth rates. For each ceiling

configuration and fire growth rate two experiments were performed. Measurements taken include 

the time to sprinkler activation, temperature and velocity of the ceiling jet at the sprinkler of 

activation, and temperatures at various other locations and elevations within the fire compartment. 

Additionally, all geometries were modeled using the National Institute of Standards and 

Technology (NIST) computational fluid dynamics fire model Fire Dynamics Simulator (FDS) to

compare predicted results with the test data obtained. It was found in a majority of cases that 

simply sloping the ceiling to an angle of 13° or 24° decreased the activation time of the sprinkler 

when compared to a smooth horizontal ceiling. However adding beams to the ceiling caused an 

increase in sprinkler activation time in all but three cases. For the Fire Dynamics Simulator 

model, the best prediction was the beamed ceiling sloped at 24° where model predictions were 

within an average of 4 % of measured times. The worst case for model prediction was the smooth 

ceiling sloped at 13°; in these cases Fire Dynamics Simulator predicted activation times within an

average of 26 % of measured times. 

Key Words: beams; ceiling jets; ceilings; computer models; fire models; residential sprinklers; 

sprinkler response; sprinkler systems; 

1
1 Introduction 

The purpose of this study was to first determine the effect of ceiling geometry, including beamed, 

sloped, and sloped beamed ceilings, on the activation time of a residential sprinkler, and secondly, 

to compare predicted results from the National Institute of Standards and Technology (NIST) 

computational fluid dynamics fire model Fire Dynamics Simulator (FDS) with the actual test data 

obtained. 

Much of the hardware associated with the detection and suppression of fires in commercial, 

manufacturing, storage, and residential buildings, including thermal detectors, smoke detectors, 

and sprinklers, is located on or near the ceiling surfaces. As a fire grows, it releases energy and 

products of combustion. Due to their elevated temperature, these products of combustion are 

driven upwards by buoyancy forces. These products generate a turbulent plume of upward 

moving, elevated temperature gases. When this upward movement of gases reaches a ceiling, the 

gases spread radially outward forming a relatively thin, high temperature, high velocity turbulent 

gas flow that is referred to as a ceiling jet. This ceiling jet flow, if under a smooth horizontal 

unconfined ceiling with no ambient interference such as wind, can be assumed to spread 

axisymmetrically about the fire origin. Since much of the hardware associated with the detection 

and suppression of fires is located on or near the ceiling, this flow of gases beneath the ceiling is 

what transports the energy necessary to cause these detectors to activate. 

The response of a sprinkler is primarily a function of the physical properties of the sprinkler

thermal element, its mounting, and the temperature and velocity of the ceiling jet that flows 

around it. For smooth horizontal ceilings, temperature and velocity distributions vary both 

radially away from the fire center and vertically below the ceiling. By sloping the ceiling of a 

room, or placing obstructions such as beams on the ceiling, the flow of the ceiling jet can be 

significantly altered. At present, residential sprinklers are only listed for use under smooth 

horizontal ceilings [1,2]. Additionally, current standards used to guide the design of these systems

contain little quantitative information concerning the impact of sloped ceilings or obstructions 

such as beams on the activation time of residential sprinklers. 

Extensive studies have been conducted to characterize the ceiling jet under a smooth horizontal

ceiling. Research by Thomas [3], Pickard [4], Alpert [5,6], Heskestad and Delichatsios [7,8,9],

Motevalli and Marks [10], Motevalli and Ricciuti [11], Cooper [12,13], and Evans [14], among 

others, provide theories and correlations which attempt to quantify the temperature and velocity

profiles of the ceiling jet. Much of their work involves different techniques to predict the 

temperature and velocity of the ceiling jet both directly above and remote from the fire source. 

The issue of obstructed ceilings and their effects on sprinkler response has long been a concern of 

the fire protection community. Several studies have been conducted to provide insight into this 

issue. Taylor [15] in 1912 gives a narrative on the impact beams have on the flow of hot gases. 

The National Board of Fire Underwriters [16] conducted experiments on fire alarm thermostats 

and sprinklers under smooth and open joisted ceilings. Work has been done at Factory Mutual by

Young [17], Heskestad [18], Heskestad and Delichatsios [19,20], and Delichatsios [21]. Thomas 

in the same study mentioned above [3] also experimented with beamed ceilings. Piscione 

performed two series of experiments [22,23] on what are considered deep wood I-beams. 

Koslowski [24] developed correlations for predicting ceiling jet velocity and temperatures for a 

2
beamed ceiling that are based on smooth ceiling correlations. In all the above studies the ceilings

were horizontal. 

The effect of sloped ceilings, or as they are often called, cathedral ceilings, has not received a 

great deal of attention. The only experimental work found in the literature involving sloped 

ceilings and sprinklers was done at Factory Mutual by Bill [25,26]. Other studies involving sloped 

ceilings by Sugawa [27] and Kung [28] attempt to develop estimation models of gas temperature

and velocity under sloped ceilings. 

Computer models have become primary tools enabling engineers to analyze fire protection 

problems. Computer models for fire and smoke have been used to assist in both the design of fire 

protection systems and in the reconstruction of fires [29,30]. These models give engineers the 

capability to predict the effects of a fire on the environment within a compartment. The ability to 

predict the activation times of smoke detectors, sprinklers, or other thermal detectors is important. 

These devices not only warn occupants of a fire and summon outside help, but in the case of

sprinklers, initiate suppression of the fire. Ensuring detector actuation before a fire reaches a 

certain size is critical for the proper design of a fire detection/suppression system. 

In 1991 Friedman [31] listed 62 computer models for smoke and fire. In 2002, Friedman’s list 

was updated by Olenick and Carpenter [32] and now includes 174 computer models. Nine of 

these models were designed specifically to predict the actuation of thermal detectors. A limitation

of these models is that each assumes the thermal detector is positioned on or some distance below 

a ceiling that is smooth and horizontal. These models would not be able to predict the activation

time of a thermal detector, such as an automatic sprinkler, under a horizontal beamed, sloped, or 

sloped beamed ceiling. Forney et al. used a computational fluid dynamics model, HarwellFLOW3D to model experimental work that had been done by Heskestad and Delichatsios on the 

effects of beams on detector response [33]. Later Davis et al. expanded on this to include sloped

and sloped beamed ceilings [34]. This second report was a modeling effort to determine 

appropriate detector spacing and did not model any experimental work. The model used by 

Forney and Davis did not have a detector algorithm built in. The authors took the output from the 

FLOW3D model and input it into a stand-alone heat detector algorithm. 

The National Institute of Standards and Technology (NIST) fire model Fire Dynamics Simulator 

(FDS) is a computational fluid dynamics fire model that uses large eddy simulation techniques 

[35]. This model has been demonstrated to predict the thermal conditions resulting from a

compartment fire [36,37]. A computational fluid dynamics model requires that the room or 

building of interest be divided into small three-dimensional rectangular control volumes or 

computational cells. The CFD model computes the density, velocity, temperature, pressure and 

species concentration of the gas in each cell. Based on the laws of conservation of mass, 

momentum, species, and energy the model tracks the generation and movement of fire gases. A 

complete description of the FDS model is given in reference [35]. The heat detector actuation 

algorithm used by Fire Dynamics Simulator is based on work by Heskestad and Smith [38]. 

Smokeview is a scientific visualization program developed by Forney that displays the results of a 

FDS model computation. Smokeview produces animations or snapshots of FDS results. A 

complete description of Smokeview is given in reference [39]. 

3
2 Experimental Configuration 

These experiments were conducted at the Building and Fire Research Laboratory’s Large Fire

Facility, Building 205. The fire compartment consisted of a room 7.3 m x 5.5 m (24 ft x 18 ft) 

with an initial ceiling height of 2.4 m (8 ft). An opening measuring 1 m x 2.1 m (40 in x 82 in) 

served as the entrance to the room (Figure 3). The wall in which this opening was located is 

considered the front of the room. The walls and ceiling were constructed of a wood frame covered 

with 12.7 mm (0.5 in) thick gypsum board and the floor was 12.7 mm (0.5 in) plywood. With this

basic configuration the experiments for the smooth horizontal ceiling configuration were

performed. Once these experiments were completed, two beams were placed on the ceiling. Each 

beam measured 0.20 m (8 in) wide x 0.25 m (10 in) deep and ran the entire depth of the room from 

the front to the rear of the room. They were placed on the ceiling such that the room was divided 

into three equal bays, each 2.3 m (91 in) wide (Figure 4). After the experiments were completed 

for the horizontal beamed ceiling configuration, the front portion of the ceiling was raised 1.25 m 

(4 ft) giving the ceiling a slope of 13°, (Figure 5 and Figure 6). After the experiments were 

completed for this angle, one set with the beams and one set without the beams, the ceiling was 

raised an additional 1.25 m (4 ft) giving the ceiling a slope of 24° (Figure 5). Again the 

experiments were performed, with and without ceiling beams. 

Four quick response residential pendent sprinklers were installed on the ceiling in accordance with

the National Fire Protection Association (NFPA) 13D, Sprinkler Systems in One and Two Family 

Dwellings and Manufactured Homes [2]. The location of the four sprinklers, numbered 1 through 

4, is also shown in Figure 3. As the front portion of the ceiling was raised, the location of the 

sprinklers relative to the floor remained the same. This required moving the sprinklers toward the 

front of the room each time the front portion of the ceiling was raised. Table 1 and Table 2 below 

show the effect the additional slope had on the position of the sprinklers, the distance each

sprinkler is moved forward along the ceiling and the additional height added to the sprinklers has 

the slope of the ceiling increased. As can be seen, sloping the ceiling had the greatest effect on

sprinklers 1 and 2, which are located near the front of the room. When the front portion of the 

ceiling is raised such that the slope of the ceiling is 24°, sprinklers 1 and 2 are both moved forward 

0.4 m (16 in) and the height of the sprinkler is increased by 1.90 m (75 in). Sprinklers 3 and 4 

located near the rear wall of the room are affected the least by the sloping of the ceiling. When the 

ceiling was given a slope of 13°, sprinklers 3 and 4 were not moved forward. The distance 

required to move them in order to keep the location of sprinklers 3 and 4 the same relative to the 

floor was approximately 25 mm (1 in), which was less than the diameter of the piping holding 

them. 

Table 1 Effect on sprinklers 1 and 2 as the ceiling slope is increased to 13° and then 24°

Slope of 

ceiling 

Height added to sprinklers 1 and 2 Distance sprinklers 1 and 2 are moved 

forward along the ceiling to maintain

position relative to the floor. 

0° N/a N/a

13° 0.95 m (37 in) 0.1 m (4 in) 

24° 1.90 m (75 in) 0.4 m (16 in) 

4
Table 2 Effect on sprinklers 3 and 4 as the ceiling slope is increased to 13° and then 24°

Slope of 

ceiling 

Height added to sprinklers 3 and 4 Distance sprinklers 3 and 4 are moved 

forward along the ceiling to maintain

position relative to the floor. 

0° N/a N/a

13° 0.27 m (11 in) Sprinklers were not moved forward 

24° 0.55 m (22 in) 0.1 m (4 in) 

2.1 Instrumentation

Temperature measurements were made with 0.51 mm (0.02 in) nominal diameter type K 

thermocouples. Standard thermocouple instrumentation for all 72 experiments consisted of four 

vertical arrays of thermocouples, one array located next to each sprinkler numbered 1 through 4, 

(Figure 3). Each array was comprised of 5 thermocouples. The first four thermocouples in each 

array were always located 25 mm, 150 mm, 300 mm, and 600 mm (1 in, 6 in, 12 in, and 24 in) 

below the ceiling. The fifth thermocouple in each array was always located such that it was 1.5 m 

(5 ft) off the floor (Figure 7). 

Gas velocity measurements were recorded at all four sprinklers using bi-directional probes. Each 

sprinkler had one bi-directional probe. The bi-directional probe was located 25 mm (1 in) below 

the ceiling (Figure 7). The two openings of the bi-directional probe faced the front and rear of the 

room. These probes give velocities with 10 % over an angular range of ± 50° of the probe axis in 

any direction. 

2.2 Sprinklers 

The sprinklers used throughout these experiments were commercially available quick response 

residential pendent sprinklers. They were all from the same manufacturer and were all the same

model. The sprinklers had glass bulb elements with an activation temperature of (68 ± 2.4) °C 

(154 ± 4.3 °F). The response time index (RTI) for the sprinklers was 56 (m-s) 1/2 (100 (ft-s) 1/2). 

When installed the sprinklers were fully exposed and the center of the glass bulb element was 25 

mm (1 in) below the gypsum ceiling. For each experiment, 25 ml of water was placed in the pipe

to which the sprinkler was mounted in order to simulate the water that would normally be present 

in the sprinkler piping system. The sprinkler system was then pressurized with air to 

approximately 100 kPa (15 psi). Each sprinkler was connected to a pressure switch that was 

electronically connected to a timer. The pressure switches were set at 5 kPa (1 psi) so that upon 

sprinkler activation the drop in pressure would automatically stop the corresponding timer. 

2.3 Gas Burner 

The fire source in this experimental series consisted of a rectangular gas burner with a piloted 

ignition. The burner had dimensions of 0.7 m x 1.0 m (28 in x 40 in) and was 0.3 m (1 ft) high 

(Figure 8). A commercial grade methane was used, which was certified by the supplier to contain 

5
at least 95 % methane. The flow of methane gas to the burner was controlled by a computer 

(Figure 6). The computer was programmed to monitor the flow of methane gas through four mass

flow controllers arranged in parallel. With this configuration the heat release rate curve produced 

by the burner is one that follows the fire growth rates used in the 1999 edition of NFPA 72 

National Fire Alarm Code Appendix B [40]. The fast, medium and slow fires described by this 

NFPA standard are based on a wide variety of fires that grow with the square of time and are 

sometimes referred to as t-squared (t2

) fires. A fast developing fire is one that would take less than 

150 seconds for the fire to reach a heat release rate of 1055 kW. A medium developing fire is one 

that would take more than 150 s, but less than 600 s for the fire to reach a heat release rate of 1055 

kW. A slow developing fire is one that would take 600 or more seconds for the fire to reach a heat

release rate of 1055 kW. A mathematical representation for these curves is as follows: 

2 Q = α t &

Where: Q = heat release rate (kW) &

 α = coefficient (kW/s

2

) 

 t = time (s) 

Figure 9 shows the area bounded by the theoretical fast, medium and slow fire growth curves. For 

the purpose of this experimental series, a fast fire reached 1055 kW in 150 seconds which 

corresponds to an α equal to 0.0468 kW/s2. A slow fire reached 1055 kW in 600 seconds, which 

corresponds to an α equal to 0.00293 kW/s2

. Before the experiments were conducted, the gas 

burner was calibrated using oxygen consumption calorimetry methodology under an instrumented 

calorimetry hood [41,42]. Figure 10 demonstrates the repeatability obtained with the gas burner 

during these calibration tests. The two theoretical fire growth curves used in this experimental 

series are overlaid with data obtained from the respective burner calibration tests. For each fire 

growth rate, two calibration tests were performed. 

3 Location of Fire 

In addition to varying the heat release rate of the fire, the gas burner was placed in three different 

locations within the room (Figure 3). These locations are as follows; in the open or away from 

any wall (detached burner), against the rear wall (wall burner), and in a corner (corner burner). 

The effect of placing the burner against a wall or in a corner of the room is to restrict the

entrainment of air into the plume [43,44]. When the burner is placed away from a wall or what 

would be considered in the open, cool room air is entrained into the plume from all directions. By 

placing the burner adjacent to one or more walls, the area over which cool room air can be 

entrained into the plume is reduced. One result of this reduction in entrainment is higher flame 

heights. Since the fuel requires the same amount of air to complete the oxidation process, a

greater distance is needed for the fuel vapors to mix with the smaller quantity of air that is entering 

the plume. With these higher flame heights there is now less distance from the tip of the flame to 

the bottom of the hot upper layer for the plume to entrain cool air. The higher plume temperatures 

6
that result from the reduced cool air entrainment cause similar increases in the upper layer 

temperatures. 

4 Experimental Results 

4.1 Effect of Beamed, Sloped, and Sloped Beamed Ceilings on 

Sprinkler Activation Times 

Table 6 through Table 8 compare sprinkler activation times between smooth and beamed ceilings. 

Each table gives the burner position, the fire growth rate, the time to sprinkler activation and the

location of the sprinkler activated for each experiment. For each burner position and fire growth 

rate two experiments were performed and the average time to activation is given. The percent 

difference in average sprinkler activation time caused by the beams, whether positive or negative, 

is also given. In several cases two sprinklers are indicated as activating. In these cases the two

sprinklers activated simultaneously. 

Table 9 and Table 10 compare sprinkler activation times for the three smooth ceiling geometries 

and the three beamed ceiling geometries respectively. For each burner position and fire growth

rate two experiments were performed and the average time to activation is given. The percent 

difference in average sprinkler activation time caused by sloping the ceiling, whether positive or 

negative, is also given. 

4.2 Effect of Beamed, Sloped, and Sloped Beamed Ceilings on 

Temperatures 

Table 11 through Table 13 compare temperature readings at the 1.52 m (5 ft) elevation between 

smooth and beamed ceilings at the time of sprinkler activation. This height was chosen since it 

represents the typical elevation of the mouth and eyes of people that would be evacuating the 

room. In each table, the average temperature represents the average of the four thermocouples,

one at each sprinkler location, at the 1.52 m (5 ft) elevation. The low–high temperature is simply 

the value of the lowest temperature recorded of the four thermocouples and the highest

temperature recorded of the four thermocouples at the time of sprinkler activation. 

Table 14 and Table 15 compares these temperatures for the three smooth ceiling geometries and 

the three beamed ceiling geometries respectively. In each table, the average temperature 

represents the average of the four thermocouples, one at each sprinkler location, at the 1.52 m (5 

ft) elevation. The low–high temperature is simply the value of the lowest temperature recorded of 

the four thermocouples and the highest temperature recorded of the four thermocouples at the time

of sprinkler activation. 

5 Computer Modeling 

This experimental series consisted of 6 different ceiling geometries, 3 different burner locations, 

and 2 different fire growth rates for a total of 36 different scenarios. FDS modeling was 

performed on all 36 geometries. Since all FDS calculations are performed within a domain that is 

7
made up of rectangular blocks, each with its own rectilinear grid, the smooth horizontal ceiling 

and beamed horizontal ceilings were the least difficult to model. All obstructions within the 

model, in this case the burner, beams when applicable, and vents such as doorways are forced to 

conform with the numerical grid that is established. In all the FDS modeling efforts the grid size 

was made fine enough so that the burner, doorway, beams, and sprinkler locations were the same

as in the actual experiments. For all experiments the only dimension that changed was the ceiling 

height. As this ceiling height increased the size of the computational domain necessary for FDS 

also increased. In order to keep the grid relatively constant for all the simulations, the number of

cells that the domain was divided into also increased as the ceiling height increased. Table 3

below gives the number of cells and sizes of the cells for the three different ceiling elevations. 

Table 3 Grid resolution for various ceiling heights 

Geometry Number of cells Size of cell in 

the x direction 

(m) 

Size of cell in 

the y direction 

(m) 

Size of cell in 

the z direction 

(m) 

All simulations with 

horizontal ceiling 786,940 .05 .05 .05

All simulations with 

the ceiling sloped at 

13°

1,065,800 .05 .05 .05

All simulations with 

the ceiling sloped at 

24°

2,173,064 .05 .04 .04

Figure 12 shows the FDS model representation of a beamed horizontal ceiling scenario. In this 

case, the burner, represented by the yellow box, is in the detached position. The two beams in red 

can be seen on the ceiling. The smaller red squares on either side of the beams represent 

sprinklers. Figure 13 is the same view with the grid in the x and y directions to show how the 

beams and burner are defined by the grid. In some cases there are situations in which certain 

geometric features, such as a sloped ceiling, a curved wall, etc., do not conform to the rectangular 

grid used by FDS. In this case, the slope of the ceiling is constructed by using rectangular 

obstructions in a process known as stair stepping. Figure 14 shows the stair stepping technique 

that was used to model the ceiling when it was sloped at 13°. This figure represents a side view 

of a smooth ceiling sloped at 13°. The doorway can be seen in red. The burner in this model 

representation is placed in the corner. The four red squares on the ceiling represent the location of 

the four sprinklers. Figure 15 shows the stair stepping technique that was used to model the 

ceiling when it was sloped at 24°. This figure represents a side view of a beamed ceiling sloped at 

24°. The burner in this representation is placed against the wall. Two of the small red squares that 

represent sprinklers can be seen on the ceiling. These two squares represent sprinklers 1 and 4. 

Sprinklers 2 and 3 are located on the far side of the beams and cannot be seen in this view. 

8
5.1 Results of Computer Modeling 

Table 16 through Table 21 give comparisons between measured and predicted sprinkler activation 

times. Each table presents this information for a specific ceiling geometry. The first and second 

column of each table give the burner position, fire growth rate, time to sprinkler activation, and 

location of the sprinkler activated for each experiment. For each burner position and fire growth 

rate two experiments were performed and the average time to activation is given. The third

column gives Fire Dynamics Simulator predicted activation time and location of the activated 

sprinkler for each burner position and fire growth rate. 

Table 22 through Table 27 are comparisons of the measured temperatures at the 1.52 m (5 ft) 

elevation and the predicted values given by Fire Dynamics Simulator at the time of sprinkler 

activation. Each table presents this comparison for a specific ceiling geometry. The first column 

of each table gives the burner position and fire growth rate. The second column gives the average 

temperature, which represents the average of the four thermocouples, one at each sprinkler 

location, at the 1.52 m (5 ft) elevation. The low–high temperature is simply the value of the 

lowest temperature recorded of the four thermocouples and the highest temperature recorded of 

the four thermocouples at the time of sprinkler activation. The third column gives Fire Dynamics 

Simulator’s predicted temperatures. 

6 Uncertainty Analysis 

There are different components of uncertainty in the temperatures, activation times, gas velocities, 

and heat release rate data reported here. Uncertainties are grouped into two categories according 

to the method used to estimate them. Type A uncertainties are those which are evaluated by 

statistical methods, and Type B are those which are evaluated by other means (45). Type B

analysis of uncertainties typically involves estimating upper (+a) and lower (-a) limits for the 

quantity in question such that the probability that the value would be in the interval (± a) is nearly 

100 %. After estimating uncertainties by either Type A or B analysis, the uncertainties are

combined in quadrature to yield the combined standard uncertainty. Multiplying the combined 

standard uncertainty by a coverage factor of two results in the expanded uncertainty which 

corresponds to a 95 % confidence interval (2σ). Components of uncertainty are tabulated in Table 

4 below. 

Some of these components, such as the calibration elements, are derived from instrument

specifications, while other components, such as positioning, make use of past experience. The 

combined standard uncertainty for temperature include a component related to the position of the 

thermocouple. Each thermocouple array was carefully positioned when initially installed and was 

rechecked before each experiment. The total relative uncertainty was estimated to be ± 23 % with 

the largest component estimated as the repeatability. The total relative uncertainty for sprinkler

activation was estimated at ± 16 %. Estimating the gas velocity included components for 

calibrating the bi-directional probe and positioning each probe, as well as repeatability and random

components. Combining these components resulted in a total relative uncertainty estimate of 

± 25 % for gas velocities. For this series of experiments, the total relative uncertainty for heat 

release rate was estimated at ± 24 %. Stroup et al. [46] provides a more detailed analysis and

discussion of uncertainty in oxygen calorimetry measurements. 

9
Table 4 Uncertainty in experimental data 

Component Standard

Uncertainty

Combined Standard 

Uncertainty

Total Relative 

Uncertainty

Temperature 

 Position 

 Repeatability 

 Random

± 5 % 

± 10 % 

± 2 % 

± 11 % ± 23 % 

Sprinkler Activation 

 Time

 Repeatability 

 Random

± 3 % 

± 7 % 

± 2 % 

± 8 % ± 16 % 

Gas Velocity 

 Calibration 

 Position 

 Repeatability 

 Random

± 2 % 

± 7 % 

± 10 % 

± 2 % 

± 13 % ± 25 % 

Heat Release Rate 

 Calibration 

 Repeatability 

 Random

± 5 % 

± 10 % 

± 4 % 

± 12 % ± 24 % 

Note: Random and repeatability evaluated as Type A, other components as Type B 

7 Discussion 

7.1 Discussion of Experimental Results 

From data on sprinkler activation times given in Table 6 through Table 8 it can be seen that 

placing beams on the ceiling when the burner is in the detached or wall position resulted in an

increase in sprinkler activation times. For the case where the burner is placed in the corner there is 

no clear trend. One burner configuration that stands out is the case where the burner is positioned 

against the wall. When the burner is in this position and the ceiling is either horizontal smooth or

horizontal beamed, sprinkler 3 or 4 activate first. This seems reasonable since these two are the 

closest to the burner when the burner is positioned against the wall (Figure 3). For the smooth 

ceiling geometry and the ceiling sloped to either 13° or 24°, either sprinkler 3 or 4 still activate

first. However, when the ceiling is sloped and beamed, either sprinkler 1 or 2 activate first in all 

10
experiments. Figure 11 shows the distance between the burner and the sprinklers when the burner 

is placed against the wall. Sprinklers 1 and 2 are approximately 4.2 m (13.7 ft) and sprinklers 3 

and 4 are approximately 2.0 m (6.6 ft) from the burner. In these particular geometries it appears 

that the beams combined with the sloped ceiling have altered the ceiling jet flow in such a way 

that a sprinkler that is twice as far from the burner would activate first. A similar situation was 

observed in another study [47] in which ceiling obstructions, in this case floor joists, caused 

sprinklers other than the closest to activate first. 

Referencing data from Table 9, and using the smooth horizontal ceiling as a basis, increasing the 

slope of the ceiling to either 13° or 24°, and placing the burner either in the detached position or 

wall position, the result was a decrease in the activation time in all but one case. In this one case, 

detached burner, fast fire growth rate, and the ceiling sloped at 24° the increase in activation time 

was only 3 s over the smooth horizontal activation time. Referencing data from Table 10, and 

using the beamed horizontal ceiling as a basis, increasing the slope of the ceiling to 13° appeared 

to have little effect on activation time. In two cases there was no change, in one an increase, and 

one a decrease. When the ceiling slope is increased to 24° in all cases the time to sprinkler 

activation is increased. In either case, smooth ceiling or beamed ceiling, when the burner is placed 

in the corner, increasing the ceiling slope to either 13° or 24° caused an increase in the activation 

time. 

In the geometries in which the burner was in the detached position or against the wall, placing

beams on the ceiling, Table 11 through Table 13, caused higher temperatures at the 1.52 m (5 ft)

elevation at sprinkler activation when compared to smooth ceilings at the same slope. When the

burner was placed in the corner the temperatures were nearly identical. 

Referencing data from Table 14, and using the smooth horizontal ceiling as a basis, sloping the 

ceiling to either 13° or 24° and placing the burner either in the detached position or wall position, 

the effect in all cases was a decrease in average temperature recorded at the 1.52 m (5 ft) level. 

Referencing data from Table 15, and using the beamed horizontal ceiling as a basis, increasing the

ceiling slope to 13° had a mixed effect. For the burner in the detached position the average 

temperature decreased. When the burner was placed against the wall there was a slight increase in 

the average temperature, and when the burner was placed in the corner there were both increases 

and decreases. When the beamed ceiling is sloped to 24° and the burner is in the detached 

position or placed against the wall, the average temperature decreases. At this angle and the 

burner in the corner, again there are increases and decreases in the average temperature when 

compared to the horizontal beamed ceiling. 

As a point of reference, The National Fire Protection Handbook [48] summary of the UL 1626 test 

criteria [49] states: 

The maximum gas or air temperature adjacent to the sprinkler 76.2 mm (3 in) 

below the ceiling and 203 mm (8 in) horizontally away from the sprinkler must not 

exceed 316 °C (600 °F). 

The maximum temperature 1.6 m (5 ft 3 in) above the floor and half the room 

length away from each wall must be less than 93 °C (200 °F) during the entire test.

11
This temperature must not exceed 54 °C (130 °F) for more than a two minute 

period. 

7.2 Discussion of Computer Modeling 

Of the six ceiling configurations tested in this experimental series, Fire Dynamics Simulator best

predicted the activation times for the beamed ceiling sloped at 24°, Table 21. For this ceiling 

configuration the model predictions were within an average of 4 % of the measured times. The 

worst case for model prediction was the smooth ceiling sloped at 13°; in these cases FDS

predicted activation times were within an average of 26 % of measured times, Table 18. Table 5 

below gives the average percent difference between the FDS predictions and measured times for

all six ceiling configurations. 

Table 5 Percent difference between FDS and average measured times 

Ceiling Configuration Average percent difference between 

FDS and measured times 

Smooth Horizontal 7 % 

Beamed Horizontal 14 % 

Smooth Ceiling Sloped at 13° 26 % 

Beamed Ceiling Sloped at 13° 11 % 

Smooth Ceiling Sloped at 24° 20 % 

Beamed Ceiling Sloped at 24° 4 % 

For all geometries involving a horizontal ceiling Fire Dynamics Simulator underpredicted the 

temperature at the 1.52 m (5 ft) level. When the ceiling had a slope of 13°, all but one case was

underpredicted. When the ceiling had a slope of 24°, 8 of the cases had temperature predictions 

over those that were measured and 4 had temperature predictions under those that were measured. 

The 4 cases in which the temperature was underpredicted were all corner burners and they were

within 4 °C of measured values. 

For the geometry in which the burner is placed against the wall, the ceiling is sloped to either 13°

or 24°, and beams are placed on the ceiling, Fire Dynamics Simulator predicted that sprinkler 1 or

2 would activate first, the same sprinklers that activated first in the experiments. Sprinklers 1 and 

2 are twice as far from the burner as sprinklers 3 and 4 (Figure 11). 

Another geometry of interest is the smooth ceiling sloped at 13°, with the burner in the detached 

position. With the ceiling sloped, sprinklers 1 and 2 are considered upward from the location 

where the fire plume intersects the ceiling and sprinklers 3 and 4 are considered downward from 

the location where the fire plume intersects the ceiling. When the fire growth rate was fast, 

sprinkler one activated first in both experiments. However, when the fire growth rate was slow,

sprinkler 1 activated first once and sprinkler 4 activated first once (Table 7). For each experiment, 

only the first sprinkler to activate is tabulated. In some cases more than one sprinkler activated at

the same time. An example of this is experiment number 6 in which sprinklers 3 and 4 activated 

simultaneously (Table 6). When the first sprinkler activated in each experiment the gas supply to

the burner was shut off. This routine shut down procedure took approximately 2 s to 4 s. It was 

12
not unusual for additional sprinklers to activate during this time. For some of the horizontal

ceiling experiments in which the burner was placed in the detached position it was not unusual for 

two or three sprinklers to activate within 4 s of each other. In two of the four experiments 

conducted under this sloped ceiling geometry, a second sprinkler activated within 4 s of the first. 

For example, in experiment number 25 sprinkler 1 activated at 71 s, at 75 s both sprinklers 2 and 4 

activated. Graphing the temperature of the ceiling jet at the sprinkler, 25 mm (1 in) below the 

ceiling for both sprinklers 1 and 4 we see that the temperature rise for both sprinklers are similar 

(Figure 16). This shows that for this burner placement and ceiling slope that the ceiling jet is able 

to penetrate downward against the slope of the ceiling to the sprinklers before the buoyancy 

component causes the ceiling jet to stop. Figure 17 shows the velocities at sprinklers 1 and 4. It 

appears that sprinkler number 1, which is upward from where the fire plume intersects the ceiling

does see a slightly higher velocity than sprinkler number 4. For this geometry, Fire Dynamics 

Simulator predictions agree well with the data. For the fast fire growth rate FDS predicts sprinkler 

4 to activate first, for the slow fire growth rate FDS predicts sprinkler 1 to activate first. Although 

FDS predicted sprinkler number 4 to activate first under the fast fire growth conditions, it 

predicted that sprinklers 1 and 2 would have activated 2 s later. For the slow fire growth sprinkler 

number 3 was predicted to activate 3 seconds after sprinkler number 1. Figure 18 and Figure 19 

are the ceiling jet temperature increases and velocities of sprinklers 1 and 4 respectively. The 

ceiling jet temperatures predicted by FDS correlate very well with measured values while the

ceiling jet velocities do not show the same degree of difference between the two sprinklers. For 

the smooth ceiling sloped at 24° only sprinklers 1 or 2 activated. 

7.2.1 Sprinkler Activation Calculations 

Early during the modeling phase of this project it was discovered that predicted sprinkler 

activation times for all geometries involving ceilings sloped at 24° were exceptionally high. To 

calculate the gas temperature of the cell in which the sprinkler is located, FDS linearly interpolates

the gas temperature using the nearest eight grid cells to the sprinkler. This was done to improve

the accuracy of the temperature prediction. However, when stair-stepping is used to define a 

sloped ceiling, it is possible that one or more of the grid cells used in the interpolation is located 

above the ceiling. Grid cells that are above the ceiling are always at ambient temperature. Figure 

1 below represents the side view of a sloped ceiling geometry. The red squares represent the stairstepping that is used to physically represent the ceiling. All cells that are above these red cells are 

at ambient temperature. The physical location of the sprinklers with the ceiling sloped at 24° and 

the stair-stepping method used in the modeling caused the sprinklers to be located in the corner of 

the stair-step as shown in Figure 1. In this situation, the cell in blue, which is above the ceiling, 

was used in the linear interpolation to calculate the gas temperature. Since eight grid cells are 

used, there are two cells that are above the ceiling that are used in the interpolation. If two out of 

eight grid cells are always at ambient temperature, it would cause the calculated gas temperature to

be low, resulting in a longer time to activation. 

In an effort to correct this, all the simulations with the ceiling sloped at 24° were again performed, 

this time with the sprinkler located one cell below its present location. This eliminated the use of 

cells above the ceiling in the calculation of the gas temperature. The activation times reported in 

this paper are from this second set of simulations. 

13
The physical location of the sprinklers with the ceiling sloped at 13° and the stair stepping method 

used in the modeling caused the sprinklers to be located near the edge of the stair step as shown in 

Figure 2 below. In this case no cells above the ceiling were used in the interpolation of the gas 

temperature. In an effort to determine the effect moving the sprinkler down one cell has on the 

predicted activation time of the sprinkler, the simulations for all the geometries involving the 

ceiling sloped at 13° were performed again, this time with the sprinkler located one cell below its 

original location, just as was done for the scenarios with the ceiling sloped at 24°. The change in 

predicted activation time caused by moving the sprinkler one cell downward was on average 2 

seconds, with 8 scenarios showing a decrease in activation time and 4 scenarios showing an 

increase. 

Future versions of FDS will not use this 8 cell method of linear interpolation to calculate cell gas

temperatures. 

 

Sprinkler location for first set

of simulations, ceiling sloped

at 24°. 

Sprinkler location for second

set of simulations, ceiling

sloped at 24°.

Figure 1 – Side view of a typical sloped ceiling configuration. Drawing not to scale. 

Sprinkler location for simulations

with ceiling sloped at 13°. 

Figure 2 – Side view of a typical sloped ceiling configuration. Drawing not to scale. 

14
8 Conclusions 

For smooth ceiling configurations it was found that increasing the ceiling slope to either 13° or 

24° had the overall effect of decreasing the average activation time of the sprinkler, except in the 

case where the burner was placed in the corner. When the burner was placed in the corner

position the average activation times increased for both the 13° and 24° slope. For beamed ceiling 

configurations, increasing the slope of the ceiling to 13° had negligible effects on activation times, 

while a ceiling slope of 24° always caused an increase in activation times. As with the smooth

ceiling configurations, placing the burner in the corner always increased the activation times when 

the ceiling was sloped to either 13° or 24°. 

For a given ceiling slope, placing beams on the ceiling had a significant effect on sprinkler 

activation. For this limited set of data, where the burner is in the detached position or placed 

against the wall, the activation times always increased. The greatest percentage increases occurred 

with the burner placed against the wall. 

For smooth ceiling configurations it was found that a ceiling slope of either 13° or 24° had the

overall effect of decreasing the average temperature recorded at the 1.52 m (5 ft) level when 

compared to a horizontal smooth ceiling. Unlike sprinkler activation times, this trend was 

followed for all burner positions. Placing beams on the ceiling did have the effect of increasing

these temperatures when compared to smooth ceilings. With beamed ceilings there were several 

instances in which the average temperature at the 1.52 m (5 ft) level was greater than the 93 °C 

maximum referenced in the National Fire Protection Handbook [48]. It should be noted that 

except for the corner position, the burner was placed such that beams obstructed the ceiling jet 

flow to the sprinklers (Figure 12). This would be considered a worse case scenario. 

Fire Dynamics Simulator was able to predict the location of the first sprinkler activated. The 

predicted activation times varied from 4 % to 26 % from the average measured times for each 

ceiling configuration. Most notably FDS was able to predict for the sloped beamed ceilings with 

the burner in the wall position that sprinklers 1 and 2 would activate first in agreement with 

experiments. Sprinklers 1 and 2 are twice as far from the burner as sprinklers 3 and 4. 

Additionally for the smooth ceiling sloped at 13° and the burner in the detached position FDS 

predictions followed very closely the experimental data with regard to which sprinkler activated 

first, ceiling jet temperatures, and time to sprinkler activation. It appears that, for this size room, 

sprinkler placement, and burner placement, this 13° slope could be treated as a horizontal ceiling 

with respect to sprinkler activation times and ceiling jet temperatures. 

Future work should be directed toward studying the effects of ceilings with greater slopes than 24°

and greater heights than 4.5 m (16 ft). Smaller slopes should also be studied to determine at what

angle the slope of the ceiling starts to have a significant effect on sprinkler activation times and

which sprinkler activates first. This may be useful if it is found that ceilings below a certain angle 

could be treated as a horizontal ceiling. Additionally, ceiling configurations where beams placed 

on the ceiling are perpendicular to each other forming pockets on the ceiling would be of interest. 

15
9 Acknowledgements 

United States Fire Administration provided funding for this work and the project was guided by 

Larry Maruskin. Appreciation is extended to Dan Madrzykowski, Jay McElroy, Laurean Delauter, 

and Gary Roadarmel of the Building and Fire Research Laboratory for setting up and conducting 

these experiments. 

16
Table 6 Sprinkler activation times for horizontal smooth and horizontal beamed ceilings 

Burner Horizontal Smooth Ceiling Horizontal Beamed Ceiling 

Position 

Fire 

Growth 

rate 

Experiment

number 

Measured activation time 

and location of sprinkler 

Experiment

number 

Measured activation time 

and location of sprinkler 

Detached Fast 1 70 s Sprinkler 2 13 76 s Sprinklers 1 + 3 

2 60 s Sprinkler 1 14 79 s Sprinklers 3 + 4 

Average 65 s Average 78 s +20 % 

Slow 3 206 s Sprinkler 1 15 215 s Sprinkler 4 

4 211 s Sprinkler 2 16 221 s Sprinkler 4 

Average 209 s Average 218 s +4 % 

Wall Fast 5 58 s Sprinkler 4 17 72 s Sprinklers 3 + 4 

6 59 s Sprinklers 3 + 4 18 79 s Sprinkler 3 

Average 59 s Average 76 s +29 % 

Slow 7 162 s Sprinkler 4 19 211 s Sprinkler 3 

8 162 s Sprinkler 4 20 174 s Sprinkler 4 

Average 162 s Average 193 s +19 % 

Corner Fast 9 35 s Sprinkler 2 21 35 s Sprinkler 2 

10 36 s Sprinkler 2 22 35 s Sprinkler 2 

Average 36 s Average 35 s -3 % 

Slow 11 104 s Sprinkler 2 23 92 s Sprinkler 2 

12 102 s Sprinkler 2 24 103 s Sprinkler 2 

Average 103 s Average 98 s -5 % 

Table 7 Sprinkler activation times for smooth and beamed ceilings sloped at 13°

Burner Smooth Ceiling Sloped at 13° Beamed Ceiling Sloped at 13°

position 

Fire 

Growth 

rate 

Experiment

Number 

Measured activation time 

and location of sprinkler 

Experiment

number 

Measured activation time 

and location of sprinkler 

Detached Fast 25 71 s Sprinkler 1 37 63 s Sprinkler 2 

26 55 s Sprinkler 1 38 71 s Sprinkler 1 

Average 63 s Average 67 s +6 % 

Slow 27 181 s Sprinkler 1 39 216 s Sprinkler 2 

28 188 s Sprinkler 4 40 222 s Sprinkler 2 

Average 185 s Average 219 s +18 % 

Wall Fast 29 40 s Sprinkler 4 41 77 s Sprinkler 1 

30 41 s Sprinkler 4 42 83 s Sprinkler 2 

Average 41 s Average 80 s +95 % 

Slow 31 146 s Sprinkler 4 43 198 s Sprinkler 2 

32 144 s Sprinkler 4 44 188 s Sprinkler 1 

Average 145 s Average 193 s +33 % 

Corner Fast 33 37 s Sprinkler 2 45 41 s Sprinkler 2 

34 41 s Sprinkler 2 46 40 s Sprinkler 2 

Average 39 s Average 41 s +5 % 

Slow 35 117 s Sprinkler 2 47 115 s Sprinkler 2 

36 120 s Sprinkler 2 48 98 s Sprinkler 2 

Average 119 s Average 107 s -10 % 

17
Table 8 Sprinkler activation times for smooth and beamed ceilings sloped at 24°

Burner Smooth Ceiling Sloped at 24° Beamed Ceiling Sloped at 24°

position 

Fire 

Growth 

rate 

Experiment

number 

Measured activation time 

and location of sprinkler 

Experiment

number 

Measured activation time 

and location of sprinkler 

Detached Fast 49 64 s Sprinklers 1 + 2 61 85 s Sprinkler 1 

50 71 s Sprinklers 1 + 2 62 80 s Sprinkler 1 

Average 68 s Average 83 s +22 % 

Slow 51 188 s Sprinkler 1 63 228 s Sprinkler 2 

52 184 s Sprinkler 2 64 231 s Sprinkler 1 

Average 186 s Average 230 s +24 % 

Wall Fast 53 51 s Sprinkler 3 65 89 s Sprinkler 1 

54 54 s Sprinkler 3 66 85 s Sprinkler 2 

Average 53 s Average 87 s +64 % 

Slow 55 156 s Sprinkler 3 67 174 s Sprinkler 2 

56 159 s Sprinkler 4 68 231 s Sprinkler 1 

Average 158 s Average 203 s +28 % 

Corner Fast 57 43 s Sprinkler 2 69 46 s Sprinkler 2 

58 45 s Sprinkler 2 70 51 s Sprinkler 2 

Average 44 s Average 49 s +11 % 

Slow 59 140 s Sprinkler 2 71 140 s Sprinkler 2 

60 147 s Sprinkler 2 72 148 s Sprinkler 2 

Average 144 s Average 144 s ±0 % 

Table 9 Sprinkler activation times for all smooth ceilings 

Burner Smooth Horizontal Ceiling Smooth 13° Sloped Ceiling Smooth 24° Sloped Ceiling

position 

Fire 

growth 

rate Exp # Measured act time and 

location of sprinkler Exp # Measured act time and location of sprinkler Exp # Measured act time andlocation of sprinkler 

Detached Fast 1 70 s Sprinkler 2 25 71 s Sprinkler 1 49 64 s Sprinklers 1 + 2 

2 60 s Sprinkler 1 26 55 s Sprinkler 1 50 71 s Sprinklers 1 + 2 

Avg 65 s Avg 63 s -3 % Avg 68 s +5 % 

Slow 3 206 s Sprinkler 1 27 181 s Sprinkler 1 51 188 s Sprinkler 1 

4 211 s Sprinkler 2 28 188 s Sprinkler 4 52 184 s Sprinkler 2 

Avg 209 s Avg 185 s -11 % Avg 186 s -11 % 

Wall Fast 5 58 s Sprinkler 4 29 40 s Sprinkler 4 53 51 s Sprinkler 3 

6 59s Sprinklers 3 + 4 30 41 s Sprinkler 4 54 54 s Sprinkler 3 

Avg 59 s Avg 41 s -31 % Avg 53 s -10 % 

Slow 7 162 s Sprinkler 4 31 146 s Sprinkler 4 55 156 s Sprinkler 3 

8 162 s Sprinkler 4 32 144 s Sprinkler 4 56 159 s Sprinkler 4 

Avg 162 s Avg 145 s -10 % Avg 158 s -2 % 

Corner Fast 9 35 s Sprinkler 2 33 37 s Sprinkler 2 57 43 s Sprinkler 2 

10 36 s Sprinkler 2 34 41 s Sprinkler 2 58 45 s Sprinkler 2 

Avg 36 s Avg 39 s +8 % Avg 44 s +22 % 

Slow 11 104 s Sprinkler 2 35 117 s Sprinkler 2 59 140 s Sprinkler 2 

12 102 s Sprinkler 2 36 120 s Sprinkler 2 60 147 s Sprinkler 2 

Avg 103 s Avg 119 s +16 % Avg 144 s +40 % 

18
Table 10 Sprinkler activation times for all beamed ceilings 

Burner Beamed Horizontal Ceiling Beamed 13° Sloped Ceiling Beamed 24° Sloped Ceiling 

position 

Fire 

growth 

rate Exp # Measured act time and 

location of sprinkler Exp # Measured act time and location of sprinkler Exp # Measured act time and location of sprinkler 

Detached Fast 13 76 s Sprinklers 1 + 3 37 63 s Sprinkler 2 61 85 s Sprinkler 1 

14 79 s Sprinklers 3 + 4 38 71 s Sprinkler 1 62 80 s Sprinkler 1 

Avg 78 s Avg 67 s -14 % Avg 83 s +6 % 

Slow 15 215 s Sprinkler 4 39 216 s Sprinkler 2 63 228 s Sprinkler 2 

16 221 s Sprinkler 4 40 222 s Sprinkler 2 64 231 s Sprinkler 1 

Avg 218 s Avg 219 s ±0 % Avg 230 s +6 % 

Wall Fast 17 72 s Sprinklers 3 + 4 41 77 s Sprinkler 1 65 89 s Sprinkler 1 

18 79 s Sprinkler 3 42 83 s Sprinkler 2 66 85 s Sprinkler 2 

Avg 76 s Avg 80 s +5 % Avg 87 s +14 % 

Slow 19 211 s Sprinkler 3 43 198 s Sprinkler 2 67 174 s Sprinkler 2 

20 174 s Sprinkler 4 44 188 s Sprinkler 1 68 231 s Sprinkler 1 

Avg 193 s Avg 193 s ±0 % Avg 203 s +5 % 

Corner Fast 21 35 s Sprinkler 2 45 41 s Sprinkler 2 69 46 s Sprinkler 2 

22 35 s Sprinkler 2 46 40 s Sprinkler 2 70 51 s Sprinkler 2 

Avg 35 s Avg 41 s +17 % Avg 49 s +40 % 

Slow 23 92 s Sprinkler 2 47 115 s Sprinkler 2 71 140 s Sprinkler 2 

24 103 s Sprinkler 2 48 98 s Sprinkler 2 72 148 s Sprinkler 2 

Avg 98 s Avg 107 s +9 % Avg 144 s +47 % 

Table 11 Temperature at the 1.52 m (5ft) elevation at the time of sprinkler activation for 

horizontal smooth and horizontal beamed ceilings 

Horizontal Smooth 

Ceiling

Horizontal Beamed 

Ceiling

Burner 

position 

Fire 

Growth 

Experiment

number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Experiment

number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Detached Fast 1 79 76 – 82 13 111 100 – 124 

2 84 76 – 90 14 119 112 – 128 

Slow 3 90 87 – 91 15 111 102 – 119 

4 92 90 – 94 16 115 112 – 116 

Wall Fast 5 59 44 – 75 17 94 92 – 96

6 58 45 – 72 18 89 86 – 92

Slow 7 71 64 – 78 19 92 88 – 95

8 70 60 – 80 20 94 91 – 97

Corner Fast 9 31 26 – 34 21 26 24 – 27

10 32 27 – 38 22 24 21 – 26

Slow 11 42 38 – 46 23 37 34 – 41

12 42 35 – 49 23 40 33 – 43

19
Table 12 Temperature at the 1.52 m (5ft) elevation at the time of sprinkler activation for 

smooth and beamed ceilings sloped at 13°

Smooth Ceiling

Sloped at 13°

Beamed Ceiling

Sloped at 13°

Burner 

position 

Fire 

Growth 

Experiment

number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Experiment

number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Detached Fast 25 63 61 – 66 37 91 82 – 97

26 64 60 – 69 38 84 75 – 90

Slow 27 72 68 – 77 39 96 89 – 101

28 79 77 – 83 40 95 89 – 101

Wall Fast 29 33 28 – 37 41 97 82 – 108

30 32 29 – 34 42 98 87 – 109

Slow 31 55 52 – 58 43 99 90 – 107

32 54 52 – 57 44 94 87 – 103

Corner Fast 33 29 27 – 31 45 27 26 – 29

34 30 28 – 32 46 28 27 – 29

Slow 35 31 29 – 32 47 29 28 – 31

36 30 29 – 31 48 28 26 – 30

Table 13 Temperature at the 1.52 m (5ft) elevation at the time of sprinkler activation for 

smooth and beamed ceilings sloped at 24°

Smooth Ceiling

Sloped at 24°

Beamed Ceiling

Sloped at 24°

Burner 

position 

Fire 

growth 

Experiment

number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Experiment

number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Detached Fast 49 59 56 – 63 61 81 74 – 88

50 60 57 – 62 62 74 70 – 82

Slow 51 74 73 – 75 63 82 78 – 87

52 71 68 – 72 64 82 81 – 84

Wall Fast 53 38 33 – 44 65 75 73 – 77

54 39 34 – 43 66 73 69 – 76

Slow 55 49 47 – 49 67 84 82 – 87

56 49 44 – 53 68 88 84 – 93

Corner Fast 57 31 29 – 36 69 29 27 – 31

58 30 28 – 34 70 29 28 – 31

Slow 59 32 31 – 34 71 30 29 – 32

60 33 30 – 35 72 31 30 – 33

20
Table 14 Temperature at the 1.52 m (5 ft) elevation for all smooth ceilings 

Burner Smooth Horizontal Ceiling Smooth 13° Sloped Ceiling Smooth 24° Sloped Ceiling

position

Fire 

growth

rate 

Exp # Avg 

temp

(°C) 

Low-High

temp

(°C) 

Exp # Avg 

temp

(°C) 

Low-High

temp

(°C) 

Exp # Avg 

temp

(°C) 

Low-High

temp

(°C) 

Detached Fast 1 79 76 – 82 25 63 61 – 66 49 59 56 – 63

2 84 76 – 90 26 64 60 – 69 50 60 57 – 62

Slow 3 90 87 – 91 27 72 68 – 77 51 74 73 – 75

4 92 90 – 94 28 79 77 – 83 52 71 68 – 72

Wall Fast 5 59 44 – 75 29 33 28 – 37 53 38 33 – 44

6 58 45 – 72 30 32 29 – 34 54 39 34 – 43

Slow 7 71 64 – 78 31 55 52 – 58 55 49 47 – 49

8 70 60 – 80 32 54 52 – 57 56 49 44 – 53

Corner Fast 9 31 26 – 34 33 29 27 – 31 57 31 29 – 36

10 32 27 – 38 34 30 28 – 32 58 30 28 – 34

Slow 11 42 38 – 46 35 31 29 – 32 59 32 31 – 34

12 42 35 – 49 36 30 29 – 31 60 33 30 – 35

Table 15 Temperature at the 1.52 m (5 ft) elevation for all beamed ceilings 

Burner Beamed Horizontal Ceiling Beamed 13° Sloped Ceiling Beamed 24° Sloped Ceiling

position

Fire 

growth

rate 

Exp # Avg 

temp

(°C) 

Low-High

temp

(°C) 

Exp # Avg 

temp

(°C) 

Low-High

temp

(°C) 

Exp # Avg 

temp

(°C) 

Low-High

temp

(°C) 

Detached Fast 13 111 100 – 124 37 91 82 – 97 61 81 74 – 88

14 119 112 – 128 38 84 75 – 90 62 74 70 – 82

Slow 15 111 102 – 119 39 96 89 – 101 63 82 78 – 87

16 115 112 – 116 40 95 89 – 101 64 82 81 – 84

Wall Fast 17 94 92 – 96 41 97 82 – 108 65 75 73 – 77

18 89 86 – 92 42 98 87 – 109 66 73 69 – 76

Slow 19 92 88 – 95 43 99 90 – 107 67 84 82 – 87

20 94 91 – 97 44 94 87 – 103 68 88 84 – 93

Corner Fast 21 26 24 – 27 45 27 26 – 29 69 29 27 – 31

22 24 21 – 26 46 28 27 – 29 70 29 28 – 31

Slow 23 37 34 – 41 47 29 28 – 31 71 30 29 – 32

23 40 33 – 43 48 28 26 – 30 72 31 30 – 33

21
Table 16 Comparison of experimental versus predicted activation times for the smooth 

horizontal ceiling 

Burner Position 

Fire Growth 

Rate 

Experiment 

Number 

Measured Activation

Time and Location of

Activated Sprinkler 

Predicted Activation

Time by Fire 

Dynamics Simulator 

Detached Fast 1 70 s Sprinkler 2

2 60 s Sprinkler 1

Average 65 s 71 s Sprinklers 1,2 + 3 

Slow 3 206 s Sprinkler 1

4 211 s Sprinkler 2

Average 209 s 183 s Sprinkler 3 

Wall Fast 5 58 s Sprinkler 4

6 59 s Sprinklers 3 + 4 

Average 59 s 59 s Sprinklers 3 + 4 

Slow 7 162 s Sprinkler 4

8 162 s Sprinkler 4

Average 162 157 s Sprinkler 4 

Corner Fast 9 35 s Sprinkler 2

10 36 s Sprinkler 2

Average 36 s 45 s Sprinkler 2 

Slow 11 104 s Sprinkler 2

12 102 s Sprinkler 2

Average 103 s 126 s Sprinkler 2 

Table 17 Comparison of experimental versus predicted activation times for the horizontal 

beamed ceiling 

Burner Position 

Fire Growth 

Rate 

Experiment 

Number 

Measured Activation

Time and Location of

Activated Sprinkler 

Predicted Activation

Time by Fire 

Dynamics Simulator 

Detached Fast 13 76 s Sprinklers 1 + 3 

14 79 s Sprinklers 3 + 4 

Average 78 s 80 s Sprinkler 3 

Slow 15 215 s Sprinkler 4

16 221 s Sprinkler 4

Average 218 s 213 s Sprinkler 3 

Wall Fast 17 72 s Sprinklers 3 + 4 

18 79 s Sprinkler 3

Average 76 s 81 s Sprinkler 3 

Slow 19 211 s Sprinkler 3

20 174 s Sprinkler 4

Average 193 s 214 s Sprinkler 4 

Corner Fast 21 35 s Sprinkler 2

22 35 s Sprinkler 2

Average 35 s 47 s Sprinkler 2 

Slow 23 92 s Sprinkler 2 

24 103 s Sprinkler 2

Average 98 s 126 s Sprinkler 2 

22
Table 18 Comparison of experimental versus predicted activation times for the smooth 

ceiling sloped at 13° 

Burner Position 

Fire Growth 

Rate 

Experiment 

Number 

Measured Activation

Time and Location of

Activated Sprinkler 

Predicted Activation

Time by Fire 

Dynamics Simulator 

Detached Fast 25 71 s Sprinkler 1

26 55 s Sprinkler 1

Average 63 s 76 s Sprinkler 4 

Slow 27 181 s Sprinkler 1

28 188 s Sprinkler 4

Average 185 s 194 s Sprinkler 1 

Wall Fast 29 40 s Sprinkler 4

30 41 s Sprinkler 4

Average 41 s 70 s Sprinkler 4 

Slow 31 146 s Sprinkler 4

32 144 s Sprinkler 4

Average 145 s 179 s Sprinkler 3 

Corner Fast 33 37 s Sprinkler 2

34 41 s Sprinkler 2

Average 39 s 48 s Sprinkler 2 

Slow 35 117 s Sprinkler 2

36 120 s Sprinkler 2

Average 119 s 129 s Sprinkler 2 

Table 19 Comparison of experimental versus predicted activation times for the beamed 

ceiling sloped at 13° 

Burner Position 

Fire Growth 

Rate 

Experiment 

Number 

Measured Activation

Time and Location of

Activated Sprinkler 

Predicted Activation

Time by Fire 

Dynamics Simulator 

Detached Fast 37 63 s Sprinkler 2

38 71 s Sprinkler 1

Average 67 s 82 s Sprinklers 1+2

Slow 39 216 s Sprinkler 2

40 222 s Sprinkler 1

Average 219 s 203 s Sprinkler 2 

Wall Fast 41 77 s Sprinkler 1

42 83 s Sprinkler 2

Average 80 s 83 s Sprinkler 2 

Slow 43 198 s Sprinkler 2

44 188 s Sprinkler 1

Average 193 s 214 s Sprinklers 1+2 

Corner Fast 45 41 s Sprinkler 2

46 40 s Sprinkler 2

Average 41 s 47 s Sprinkler 2 

Slow 47 115 s Sprinkler 2

48 98 s Sprinkler 2

Average 107 s 130 s Sprinkler 2 

23
Table 20 Comparison of experimental versus predicted activation times for the smooth 

ceiling sloped at 24° 

Burner Position 

Fire Growth 

Rate 

Experiment 

Number 

Measured Activation

Time and Location of

Activated Sprinkler 

Predicted Activation

Time by Fire 

Dynamics Simulator 

Detached Fast 49 64 s Sprinklers 1 + 2 

50 71 s Sprinklers 1 + 2 

Average 68 s 84 s Sprinklers 1 + 3 

Slow 51 188 s Sprinkler 1

52 184 s Sprinkler 2

Average 186 s 209 s Sprinkler 2 

Wall Fast 53 51 s Sprinkler 3

54 54 s Sprinkler 3

Average 53 s 70 s Sprinkler 3 

Slow 55 156 s Sprinkler 3

56 159 s Sprinkler 4

Average 158 s 186 s Sprinkler 3 

Corner Fast 57 43 s Sprinkler 2

58 45 s Sprinkler 2

Average 44 s 56 s Sprinkler 2 

Slow 59 140 s Sprinkler 2 

60 147 s Sprinkler 2

Average 144 s 153 s Sprinkler 2 

Table 21 Comparison of experimental versus predicted activation times for the beamed 

ceiling sloped at 24° 

Burner Position 

Fire Growth 

Rate 

Experiment 

Number 

Measured Activation

Time and Location of

Activated Sprinkler 

Predicted Activation

Time by Fire 

Dynamics Simulator 

Detached Fast 61 85 s Sprinkler 1

62 80 s Sprinkler 1

Average 83 s 87 s Sprinkler 1 

Slow 63 228 s Sprinkler 2

64 231 s Sprinkler 1

Average 230 s 218 s Sprinklers 1 + 2 

Wall Fast 65 89 s Sprinkler 1

66 85 s Sprinkler 2

Average 87 s 88 s Sprinkler 2 

Slow 67 174 s Sprinkler 2

68 231 s Sprinkler 1

Average 203 s 233 s Sprinkler 2 

Corner Fast 69 46 s Sprinkler 2

70 51 s Sprinkler 2

Average 49 s 56 s Sprinkler 2 

Slow 71 140 s Sprinkler 2 

72 148 s Sprinkler 2

Average 144 s 149 s Sprinkler 2 

24
Table 22 Comparison of predicted versus measured temperature at the 1.52 m (5ft) elevation 

at the time of sprinkler activation for the horizontal smooth ceiling 

Measured Temperature at 1.52 m 

elevation at time of measured sprinkler

activation 

Predicted temperature at 1.52 m 

elevation at time of predicted sprinkler

activation 

Burner 

position 

Fire 

growth 

Experiment

Number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Predicted average 

temperature 

(°C) 

Predicted low –

high temperatures 

(°C) 

Detached Fast 1 79 76 – 82 63 57 – 73

2 84 76 – 90

Slow 3 90 87 – 91 61 54 – 64

4 92 90 – 94 

Wall Fast 5 59 44 – 75 39 35 – 41

6 58 45 – 72

Slow 7 71 64 – 78 41 36 – 44

8 70 60 – 80

Corner Fast 9 31 26 – 34 28 25 – 36

10 32 27 – 38

Slow 11 42 38 – 46 29 26 – 32

12 42 35 – 49

Table 23 Comparison of predicted versus measured temperature at the 1.52 m (5ft) elevation 

at the time of sprinkler activation for the horizontal beamed ceiling 

Measured Temperature at 1.52 m 

elevation at time of measured sprinkler

activation 

Predicted temperature at 1.52 m 

elevation at time of predicted sprinkler

activation 

Burner 

position 

Fire 

growth 

Experiment

Number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Predicted average 

temperature 

(°C) 

Predicted low –

high temperatures 

(°C) 

Detached Fast 13 111 100 – 124 91 79 – 102

14 119 112 – 128 

Slow 15 111 102 – 119 69 63 – 79

16 115 112 – 116 

Wall Fast 17 94 92 – 96 90 79 – 98

18 89 86 – 92

Slow 19 92 88 – 95 63 62 – 65

20 94 91 – 97

Corner Fast 21 26 24 – 27 24 21 – 26

22 24 21 – 26

Slow 23 37 34 – 41 31 29 – 33

24 40 33 – 43

25
Table 24 Comparison of predicted versus measured temperature at the 1.52 m (5ft) elevation 

at the time of sprinkler activation for the smooth ceiling sloped at 13°

Measured Temperature at 1.52 m 

elevation at time of measured sprinkler

activation 

Predicted temperature at 1.52 m 

elevation at time of predicted sprinkler

activation 

Burner 

position 

Fire 

growth 

Experiment

Number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Predicted average 

temperature 

(°C) 

Predicted low –

high temperatures 

(°C) 

Detached Fast 25 63 61 – 66 59 54 – 62

26 64 60 – 69

Slow 27 72 68 – 77 55 48 – 59

28 79 77 – 83

Wall Fast 29 33 28 – 37 46 42 – 48

30 32 29 – 34

Slow 31 55 52 – 58 48 45 – 50

32 54 52 – 57

Corner Fast 33 29 27 – 31 27 27 – 27

34 30 28 – 32

Slow 35 31 29 – 32 27 27 – 27

36 30 29 – 31

Table 25 Comparison of predicted versus measured temperature at the 1.52 m (5ft) elevation 

at the time of sprinkler activation for the beamed ceiling sloped at 13°

Measured Temperature at 1.52 m 

elevation at time of measured sprinkler

activation 

Predicted temperature at 1.52 m 

elevation at time of predicted sprinkler

activation 

Burner 

position 

Fire 

growth 

Experiment

Number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Predicted average 

temperature 

(°C) 

Predicted low –

high temperatures 

(°C) 

Detached Fast 37 91 82 – 97 77 72 – 84

38 84 75 – 90

Slow 39 96 89 – 101 58 53 – 64

40 95 89 – 101

Wall Fast 41 97 82 – 108 83 76 – 90

42 98 87 – 109

Slow 43 99 90 – 107 65 60 – 71

44 94 87 – 103

Corner Fast 45 27 26 – 29 26 26 – 26

46 28 27 – 29

Slow 47 29 28 – 31 26 26 – 27

48 28 26 – 30

26
Table 26 Comparison of predicted versus measured temperature at the 1.52 m (5ft) elevation 

at the time of sprinkler activation for the smooth ceiling sloped at 24°

Measured Temperature at 1.52 m 

elevation at time of measured sprinkler

activation 

Predicted temperature at 1.52 m 

elevation at time of predicted sprinkler

activation 

Burner 

position 

Fire 

growth 

Experiment

Number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Predicted average 

temperature 

(°C) 

Predicted low –

high temperatures 

(°C) 

Detached Fast 49 59 56 – 63 92 83 – 104

50 60 57 – 62

Slow 51 74 73 – 75 79 77 – 81

52 71 68 – 72

Wall Fast 53 38 33 – 44 67 65 – 74

54 39 34 – 43

Slow 55 49 47 – 49 67 65 – 68

56 49 44 – 53

Corner Fast 57 31 29 – 36 28 28 – 29

58 30 28 – 34

Slow 59 32 31 – 34 29 29 – 29

60 33 30 – 35

Table 27 Comparison of predicted versus measured temperature at the 1.52 m (5ft) elevation 

at the time of sprinkler activation for the beamed ceiling sloped at 24°

Measured Temperature at 1.52 m 

elevation at time of measured sprinkler

activation 

Predicted temperature at 1.52 m 

elevation at time of predicted sprinkler

activation 

Burner 

position 

Fire 

growth 

Experiment

Number 

Average

temp

(°C) 

Low – High

temp

(°C) 

Predicted average 

temperature 

(°C) 

Predicted low –

high temperatures 

(°C) 

Detached Fast 61 81 74 – 88 114 105 – 123 

62 74 70 – 82

Slow 63 82 78 – 87 82 79 – 87

64 82 81 – 84

Wall Fast 65 75 73 – 77 113 103 – 121 

66 73 69 – 76

Slow 67 84 82 – 87 42 40 – 45

68 88 84 – 93

Corner Fast 69 29 27 – 31 28 28 – 28

70 29 28 – 31

Slow 71 30 29 – 32 29 28 – 29

72 31 30 – 33

27
5.50m

3.15m 1.00m

7.30m

1 2

4 3

Corner 

burner

Detached 

burner

Wall burner

1.85m

1.25m

3.65m

1.25m

Figure 3 Plan view of experimental set up. 

2.45m

2.30m 2.30m 2.30m

Beams

3.15m 1.00m

Figure 4 Front view of experimental set up. 

28
2.45m

1.25m

1.25m

13°

24°

4.95m

5.5m

Figure 5 Side view of the test room showing different elevation and angles of the ceiling. 

Figure 6 View of the test room. The ceiling in this picture is sloped at 13°. The burner mass 

flow controller can be seen at the bottom of the figure along with the methane gas 

bottles. 

29
300mm 600mm

150mm

This thermocouple always

1.5 m above floor

Ceiling

Velocity Probe

Sprinkler

25mm

Figure 7 Instrumentation set up for each sprinkler. All thermocouples maintained same

distance from the ceiling regardless of ceiling height except for the lowest 

thermocouple which was always maintained at a distance of 1.5 m from the floor. 

Figure 8 Gas burner placed for a corner experiment. 

30
0

100

200

300

400

500

600

700

800

900

1000

1100

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700

Time (s)

Heat Release Rate (kW)

Fast fire growth 

region

Medium fire growth region

Slow fire growth region 

Figure 9 Fast, medium, and slow fire growth regions. 

0

200

400

600

800

1000

1200

0 100 200 300 400 500 600 700

Time (s)

Heat Release Rate (kW)

Fire growth with

alpha = 0.0468

Fire growth with alpha = 

0.00293

Figure 10 Calibration data for the rectangular gas burner. 

31
7.3m

5.5m

2.0m

4.2m

2.0m

4.2m

Sprinkler 1 Sprinkler 2

Sprinkler 4 Sprinkler 3

Figure 11 Distance between sprinklers and burner when the burner is placed against the wall. 

Figure 12 Front view of modeled room showing doorway, beams, burner, and sprinklers. The 

burner in this scenario is in the detached position.

32
Figure 13 Horizontal beamed ceiling model representation showing grid in the x and y 

directions. 

Figure 14 Side view of FDS representation of smooth sloped ceiling sloped at 13°. In this 

scenario the burner is placed in the corner. The four red squares on the ceiling 

represent sprinklers. 

33
Figure 15 Side view of FDS model representation of beamed sloped ceiling sloped at 24°. 

The two beams are shown in red and the two small red dots on the ceiling represent 

sprinklers 1 and 4. 

0

10

20

30

40

50

60

70

80

90

100

110

120

130

140

0 10 20 30 40 50 60 70 80

Time (s)

Increase In Ceiling Jet Temperature (oC)

Sprinkler 1

Sprinkler 4

Figure 16 Increase in ceiling jet temperature for sprinklers 1 and 4 for experiment number 25, 

smooth ceiling sloped at 13° and burner in the detached position. 

34
0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 10 20 30 40 50 60 70 80

Time (s)

Velocity (m/s)

Sprinkler 1

Sprinkler 4

Figure 17 Ceiling jet velocity at sprinklers 1 and 4 for experiment number 25, smooth ceiling 

sloped at 13° and the burner in the detached position. 

0

20

40

60

80

100

120

140

0 10 20 30 40 50 60 70 80

Time (m/s)

Increase in Ceiling Jet Temperature (oC)

Sprinkler 1

Sprinkler 4

Figure 18 FDS prediction for sprinklers 1 and 4 ceiling jet temperature, smooth ceiling sloped 

at 13° and burner in the detached position. 

35
0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 10 20 30 40 50 60 70 80

Time (s)

Ceiling Jet Velocity (m/s)

Sprinkler 1

Sprinkler 4

Figure 19 FDS prediction for sprinklers 1 and 4 ceiling jet velocities, smooth ceiling sloped at 

13° and burner in the detached position. 

36
10 References 

1 Underwriters Laboratory Inc., UL 1626 “Standard for Residential Sprinklers for Fire 

Protection Service,” Second Edition, September 30, 1994. 

2 National Fire Protection Association, “National Fire Protection Association 13D Sprinkler 

Systems in One and Two Family Dwellings and Manufactured Homes,” 1993 Edition,

National Fire Protection Association, Quincy, MA 02169. 

3 Thomas, P. H., “The Distribution of Temperature and Velocity Due to Fires Beneath 

Ceilings,” F.R. Note 141, Fire Research Station Borehamwood, England, 1955. 

4 Pickard, R. W., Hird, D., and Nash, P., “The Thermal Testing of Fire Sensitive Detectors,”

F.R. Note 247, Fire Research Station Borehamwood, England, 1957. 

5 Alpert, R. L., “Fire Induced Turbulent Ceiling Jet,” Factory Mutual Research Corporation,

Norwood MA. FMRC Serial Number 19722-2, May 1971.

6 Alpert, R. L., “Calculations of Response Time of Ceiling Mounted Fire Detectors,” Fire 

Technology, Vol. 8, No. 3, pp 181-195, August 1972. 

7 Heskestad, G., and Delichatsios, M. A., “The Initial Convective Flow in Fire,” Seventeenth 

Symposium on Combustion, The Combustion Institute, pp 1113-1123, August 1978.

8 Heskestad, G., and Delichatsios, M. A., “Environments of Fire Detectors – Phase I: Effect 

of Fire Size, Ceiling Height and Material, Volume I – Measurements,” NBS-GCR-77-86, 

National Institute of Standards and Technology, 1977. 

9 Heskestad, G., and Delichatsios, M. A., “Environments of Fire Detectors – Phase I: Effect 

of Fire Size, Ceiling Height and Material, Volume II – Analysis,” NBS-GCR-77-95, 

National Institute of Standards and Technology, 1977. 

10 Motevalli, V., and Marks, C. H., “Transient Characteristics of Unconfined Fire Plume 

Driven Ceiling Jets,” NIST-GCR-90-574, National Institute of Standards and Technology, 

August 1989. 

11 Motevalli, V., and Ricciuti, C., “Characterization of the Confined Ceiling Jet in the 

Presence of an Upper Layer in Transient and Steady State Conditions,” NIST-GCR-92-

613. National Institute of Standards and Technology, August 1992. 

12 Cooper, L. Y., “Convective Heat Transfer to Ceilings Above Enclosure Fires,” Nineteenth

Symposium on Combustion. pp 933-939, 1982. 

13 Cooper, L. Y., “A Buoyant Source in the Lower of Two, Homogeneous, Stably Stratified 

Layers,” Twentieth Symposium on Combustion, pp 1567-1573, 1982. 

14 Evans, D. D., “Calculating Sprinkler Actuation Time in Compartments,” Fire Safety 

Journal, Vol. 9, No. 2, pp147-155, 1985. 

15 Taylor F., “The Automatic Control of Fire,” Quarterly of the National Fire Protection

Association, October 1912, pp149-162. 

16 National Board of Fire Underwriters, “Fire Alarm Thermostat Tests Comparison of 

Operation of Fire Alarm Thermostats Under Smooth Ceilings and Open Joisted 

Construction,” 1956. 

37
 

17 Young, J. R., “Spacing Automatic Sprinklers,” Quarterly of the National Fire Protection 

Association, October 1960, pp120-128. 

18 Heskestad, G., “Model Study of ESFR Sprinkler Response Under Beamed Ceilings,” 

Technical Report, FMRC J.I. 0N0E3.RU. Factory Mutual Research Corporation,

Norwood, MA, July 1987. 

19 Heskestad, G., and Delichatsios, M. A., “Environments of Fire Detectors – Phase II: Effect

of Ceiling Configuration, Volume I – Measurements,” NBS-GCR-78-128, National 

Institute of Standards and Technology, 1978. 

20 Heskestad, G., and Delichatsios, M. A., “Environments of Fire Detectors – Phase II: Effect

of Ceiling Configuration, Volume II – Analysis,” NBS-GCR-78-129, National Institute of 

Standards and Technology, 1978. 

21 Delichatsios, M. A., “The Flow of Fire Gases Under a Beamed Ceiling,” Combustion and 

Flame Vol. 43, pp1-10, 1981. 

22 Piscione, J., and Vogt, J., “Fire Sprinklers in Exposed Deep Prefabricated Wood “I” Joist 

Floor and Roof Systems,” Truss Joist Corporation or Truss Joist MacMillan. 200 East 

Mallard Drive Boise Idaho 83706, February 1989. 

23 Piscione, J., and Pintar, P., “Fire Sprinklers in Exposed 30 Inch Deep Prefabricated “I” 

Joist Floor and Roof Systems Phase II,” Truss Joist Corporation or Truss Joist MacMillan. 

200 East Mallard Drive Boise Idaho 83706 November, 1989. 

24 Koslowski, C. C., “Effects of Beams and Ceiling Obstructions on Steady State Ceiling Jet 

Flow,” Masters Thesis, Worcester Polytechnic Institute, December 1991. 

25 Bill, R. G., Hsiang-Cheng, K., Brown, W. R., and Hill, E. E., “Effects of Cathedral and 

Beamed Ceiling Construction on Residential Sprinkler Performance,” Fire Safety Science 

Proceedings of the Second International Symposium, pp 643-653. 

26 Bill, R. G., Hill, E. E., “Sprinkler Protection of Manufactured Homes with Sloped Ceilings 

Using Prototype Limited Water Supply Sprinklers,” Fire Technology, Vol. 31 No. 1, pp 

17-43, First Quarter 1995. 

27 Sugawa, O., “Simple Estimation Model on Ceiling Temperature and Velocity of Fire 

Induced Flow Under Ceiling,” Fire Science and Technology, Vol. 21 No.1 pp 57-67, 2001. 

28 Kung, H. C., Spaulding, R. D., Stavrianidis, P., “Fire Induced Flow Under a Sloped 

Ceiling,” Fire Safety Science, Proceedings of the Third International Symposium, pp 271-

280. 

29 Stroup, D. W., “Analyzing Fire Safety Through Computer Modeling and Product Testing,” 

General Services Administration, Washington DC, Interscience Communications Limited. 

Fires and Materials. 2nd International Conference, September 23-24, 1993 Arlington, 

Virginia, pp 7-12. 

30 Madrzykowski, D.; Vettori, R. L.; “Simulation of the Dynamics of the Fire at 3146 Cherry 

Road NE, Washington, DC, May 30, 1999,” National Institute of Standards and 

Technology, Gaithersburg, MD, NISTIR 6510, April 2000. 

38
 

31 Friedman, R., “An International Survey of Computer Models for Fire and Smoke Second 

Edition,” Factory Mutual Research Corporation. Norwood, MA, 02062, December 1991. 

32 Olenick, S. M., and Carpenter, D. J., "An Updated International Survey of Computer 

Models for Fire and Smoke," submitted to the SFPE Journal of Fire Protection

Engineering, 2002. 

33 Forney, G. P., Bukowski, R. W., and Davis, William D., “Field Modeling: Effects of Flat 

Beamed Ceilings on Detector and Sprinkler Response,” National Fire Protection Research

Foundation, Batterymarch Park, Quincy, Massachusetts 02169, October 1993. 

34 Davis, W. D., Forney, G. P., and Bukowski, R. W., “Field Modeling: Simulating the Effect 

of Sloped Beamed Ceilings on Detector and Sprinkler Response,” National Fire Protection

Research Foundation, Batterymarch Park, Quincy, Massachusetts 02169, October 1994. 

35. McGrattan, Kevin B.; Baum, Howard R.; Rehm, Ronald G.; Hamins, Anthony; Forney, 

Glenn P.; “Fire Dynamics Simulator – Technical Reference Guide,” National Institute of

Standards and Technology, Gaithersburg, MD, NISTIR 6467, January 2000. 

36. McGrattan, Kevin B.; Hamins, Anthony; and Stroup, David; “Sprinkler, Smoke & Heat 

Vent, Draft Curtain Interaction – Large Scale Experiments and Model Development,”

National Institute of Standards and Technology, Gaithersburg, MD, NISTIR 6196-1, 

September 1998. 

37. McGrattan, Kevin B.; Baum, Howard R.; Rehm, Ronald G.; “Large Eddy Simulations of 

Smoke Movement,” Fire Safety Journal, vol 30 (1998), pp 161-178. 

38 Heskestad, G., and Smith, H. F., “Technical Report Investigation of a New Sprinkler 

Sensitivity Approval Test: the Plunge Test,” Factory Mutual Research Corporation,

Norwood, Massachusetts 02062. December 1976. 

39. Forney, Glenn P., McGrattan, Kevin B., “User’s Guide for Smokeview Version 3.1 – A 

Tool for Visualizing Fire Dynamics Simulation Data,” National Institute of Standards and 

Technology, Gaithersburg, MD, NISTIR 6980, April 2003. 

40 National Fire Protection Association, “National Fire Protection Association 72 Standard 

National Fire Alarm Code Appendix B,” 1993 Edition. National Fire Protection

Association, Quincy, MA 02169. 

41 Parker, W. J., “Calculations of the Heat Release Rate by Oxygen Consumption For

Various Applications,” Journal of Fire Sciences, Vol. 2, No, 2, 380-395, 

September/October 1994. 

42 Janssens, M. L., “Measuring Rate of Heat Release by Oxygen Consumption,” Fire 

Technology, Vol. 27, No. 3, 234-249, August 1991. 

43 Zukoski, E. E., Kubota, T., and Cetegen, B., “Entrainment in Fire Plumes,” NBS-GCR-80-

294, National Bureau of Standards, November 1980. 

44 Alpert, R. L., and Ward, E. G., “Evaluating Unsprinklered Fire Hazards,” Factory Mutual 

Research Corporation, Norwood, MA, SFPE TR 83-02, FMRC J. I. 01836.20, August 

1982. 

39
 

45 Taylor, B.N., Kuyatt, C. E., “Guidelines for Evaluating and Expressing the Uncertainty of 

NIST Measurements Results,” NIST Technical Note 1291, National Institute of Standards 

and Technology, Gaithersburg, MD 20899, 1994. 

46 Stroup, D. W., Delauter, L. A., Lee, J. H., Roadarmel, G. L. “Large Fire Research Facility 

(Building 205) Exhaust Hood Heat Release Rate Measurement System,” National Institute 

of Standards and Technology, Gaithersburg, MD 20899, July 2000. 

47 Vettori, R. L., “Effect of an Obstructed Ceiling on the Activation Time of a Residential 

Sprinkler NISTIR 6253,” National Institute of Standards and Technology, Gaithersburg, 

MD 20899, Nov. 1998. 

48 National Fire Protection Association, “National Fire Protection Association Fire Protection

Handbook 18th Edition Section 6 p 191,” National Fire Protection Association, Quincy, 

MA 02169. 

49 Underwriters Laboratory Inc., “UL 1626 Standard for Residential Sprinklers for Fire 

Protection Service,” Second Edition, September 30, 1994. 

40