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NBSIR 84-2819

Estimating Effectiveness of

State-of-the-Art Detectors and

Automatic Sprinklers on Life

Safety in Residential Occupancies

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

January 1 984

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NBSIR 84-2819

* Ur o to ESTIMATING EFFECTIVENESS OF

STATE-OF-THE-ART DETECTORS AND

AUTOMATIC SPRINKLERS ON LIFE

SAFETY IN RESIDENTIAL OCCUPANCIES

Edward K. Budnick

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

January 1984

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige. Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director

TABLE OF CONTENTS

Page

LIST OF FIGURES v

LIST OF TABLES vii

Abstract 1

1. INTRODUCTION 2

1.1 Residential Fire Deaths in the United States 2

1.2 Scope and Objectives 3

2. A REVIEW OF DETECTOR AND SPRINKLER TECHNOLOGY 3

2.1 The Role of Detectors and Sprinklers as Design

Options for Fire Safety..... 4

2.2 Development of Detection Technology 4

2.2.1 Limitations in Applying Commercial Detector

Technology to Residential Occupancies 6

2.2.2 Residential Detection 6

2.2.3 Field Experience 7 2.3 Development of Automatic Sprinkler Technology 7 2.3.1 Limitations in Applying Standard Sprinkler

Technology to Residential Occupancies 8

2.3.2 Residential Sprinklers..... 8

2.3.3 Field Experience 9

3. MAJOR FACTORS IN ESTIMATING POTENTIAL EFFECTIVENESS FOR

RESIDENTIAL LIFE SAFETY 10

3.1 Dominant Residential Fire Scenarios 12

3.2 Location and Capability of Occupants 13

3.3 Response Time 14

3.4 Impact on Development of Hazardous Conditions 15

4. REVIEW OF SELECTED FULL SCALE STUDIES 16

4.1 Mobile Home Studies 16

4.2 Dwelling Studies. 19

4.3 Health Care Room-Corridor Studies 21

4.4 Implications of Experimental Results for Residential

Life Safety 23

5. QUALITATIVE ASSESSMENT OF DETECTOR AND SPRINKLER

EFFECTIVENESS 28

5.1 Assessments 28

5.2 Limitations of the Assessments 30

6. TOWARD APPLICATION OF QUANTITATIVE TECHNIQUES 31

iii
TABLE OF CONTENTS (continued)

Page

7 . SUMMARY AND CONCLUSIONS 35

8 . ACKNOWLEDGMENTS 37

9 . REFERENCES 37

iv
LIST OF FIGURES

Page

Figure 1. Occupancy Distribution of 1981 Fire Losses 43

Figure 2. Causes of 1981 Residential Fires 44

Figure 3. Growth of Smoke Detector Usage in Single Family

Dwellings 45

Figure 4. Typical Standard Sprinkler Head and Residential

Sprinkler Head Demonstrating Significant Reduction

in Thermal Link Mass for Residential Sprinkler

Technology. 46

Figure 5 . Eye Level Temperature and Smoke Density in Room of Fire

Origin where Residential Sprinkler Controlled the

Fire 47

Figure 6. Illustration of Characteristic Residential Compartment

Fires 47

Figure 7. Parametric Model - Residential Life Safety Scenarios.... 48

Figure 8. Comparison of Activation Times for Smoke Detector (A)

and Sprinkler (B) for Typical Compartment Fire 49

Figure 9. Graphical Illustration of Escape Time (AT) provided by

Smoke Detector Alarm 49

Figure 10. Graphical Illustration of Potential Impact of

Sprinklers in Preventing Hazardous Conditions 50

Figure 11. Ceiling Gas Temperature and Activation Times: Test 10... 51

Figure 12. Ceiling Gas Temperature and Activation Times: Test 11... 52

Figure 13. Measured Conditions for Flaming Upholstered Chair 53

Figure 14. Measured Conditions for Smoldering Upholstered Chair.... 54

Figure 15. Escape Time for Smoke Detectors Installed on Every

Level 55

Figure 16. Escape Time for Fixed Temperature Heat Detectors

Installed in Room of Origin 56

Figure 17. Ceiling Gas Temperatures in Bedroom Adjacent to Closet

for Sprinklered and Unsprinklered Flaming Closet Fires.. 57

Figure 18 . Upper Room Gas Temperatures and Sprinkler Activation

Times for Smoldering Bedroom Fires 58

v
LIST OF FIGURES (continued)

Figure 19. Estimated Escape Time from Patient Room and Along

Corridor Provided by Different Detector Types

and Locations for Flaming Mattress Fires

Figure 20. Comparison of Ceiling Gas Temperatures and Sprinkler

Activation Times for Flaming Mattress Tests...

Figure 21. Effect of Different Sprinkler Activation Times on Smoke Filling in Doorway and in Corridor

Figure 22. Illustration of Similar Times to Activation for

Residential and Standard Sprinklers under Severe Early

Fire Growth from Shielded Combustible Wardrobe Fires....

Figure 23. Parameter Combinations for Scenario Group //

Figure 24. Residential Life Safety Model

Figure 25. Life Safety Objective for Residential Occupancies:

l MS > 0

Figure 26. Relationship of Terms in Expression Proposed for Life

Safety (TMg » (T„ - Tp) - Tj R

> 0 ) to Residential

Life Safety *

l MS " V/H A D

; Model,

vi

Page

59

60

61

62

63

64

65

66
LIST OF TABLES

Page

Table 1. Deaths Per Fire: One and Two Family Dwellings 67

Table 2. Peak Levels of Selected Hazard Measurements at Eye

Level Elevation 68

Table 3. Peak Levels of Selected Hazard Measurements at Eye

Level Elevation..... 69

Table 4a. Occupant Conditions where Detectors or Sprinklers

Provide Protection - Smoldering/Flaming Scenarios 70

Table 4b. Occupant Conditions where Detectors or Sprinklers

Provide Protection - Flaming Scenarios 71

Table 4c. Occupant Conditions where Detectors or Sprinklers

Provide Protection - Shielded Fast Flaming Scenarios.... 72

Table 5. Estimated Protection Provided by Detectors and

Sprinklers for Major Interior Fire Scenario Groups in

Residential Occupancies 73

vii

ESTIMATING EFFECTIVENESS OF STATE-OF-THE-ART

DETECTORS AND AUTOMATIC SPRINKLERS ON LIFE

SAFETY IN RESIDENTIAL OCCUPANCIES

Edward K. Budnick

Abstract

The report provides a qualitative assessment of the

life safety impact of early warning fire detection and

automatic sprinkler technology in residential occupancies. This assessment is based on the results of full

scale studies and statistics on residential fire fatalities from the NFIRS data base.

Estimates of the impact of three alternatives, smoke

detectors, standard automatic sprinklers, and residential

sprinklers, are provided for major fire hazard scenarios

in residential occupancies. The results of this study

indicate that significant life safety benefits can be

derived from broad application of detectors and sprinklers in all residential buildings. Further work is

necessary to reduce the gaps which exist in our understanding of the performance limits, cost-effectiveness,

and reliability of these devices. In addition, there are residential scenarios, for example, occupants intimately

exposed to a fire, where the impact of these devices

appears marginal.

A quantitative approach is outlined that can lead to

a more accurate assessment of the impact of detectors and

sprinklers. An initial framework is presented which

identifies the key parameters for residential life

safety. A mathematical expression is proposed as a success criterion. Work is underway to extend the

framework.

1
Key Words: Fire losses; life safety; residential

buildings; residential sprinklers, smoke detectors;

standard sprinklers.

1. INTRODUCTION

1.1 Residential Fire Deaths in the United States

It is well recognized that most fire deaths in the U.S. occur in

residential fires. While some variations occur in the statistics from year to

year, "fire deaths in residences" has remained the dominant category for many

years

In 1973, the report of the National Commission on Fire Prevention and

Control estimated that 90 percent of the fire deaths occurred in residential

occupancies [1]*. While the notion that residential fire losses represented a significant portion of the annual fire losses in the U.S. was not novel, the

estimate of the magnitude reported by the Commission drew considerable

concern.

Subsequently, the National Fire Incident Reporting System (NFIRS) was created at the U.S. Fire Administration (USFA) to provide accurate, more

detailed reporting of the annual fire losses in the U.S. The most current

data from this reporting system (1981) does not vary appreciably from the 1973

estimate from the Commission. The NFIRS data indicates continued overwhelming

dominance of residential fires as a source of fire deaths in the U.S. As can

be seen in figure 1, while residential fires account for only 25 percent of

the annual fires, they account for 80 percent of the deaths and 65 percent of

the injuries [2]

Of the variety of causes of residential fires, four account for the bulk

of fires resulting in deaths and injuries (figure 2). They are smoking,

heating, cooking and incendiary/ suspicious

1 Numbers in brackets indicate literature references at end of this paper.

2
Finally, the 1981 NFIRS data indicate that the most frequent fatal fire

scenarios in residential occupancies involve a single death. While multiple

life loss fires are a major concern for some residential occupancies (i.e.,

apartments, hotels and motels, dormitories), in a sample of one and two family

residential fires most deaths (94 percent) occurred one or two at a time (see

table 1).

1.2 Scope and Objectives

During the last decade the fire community has directed much of its

attention to the matter of life safety, and how advances in technology might

reduce the annual fire deaths and injuries in the United States. The National

Bureau of Standards' (NBS) Center for Fire Research (CFR) has conducted

research in support of this objective, including studies to contribute to the

advancement of early warning fire detection and automatic sprinkler technology

relative to life safety. Of particular interest to NBS is the application of

O such technology in residential occupancies .

This report focuses on the life safety aspects of state-of-the-art early

warning fire detection and automatic sprinkler technology. A review of significant technical advancements is provided and an assessment of the potential

impact of these advancements on residential fire deaths is presented. This

assessment is based on the results of experimental research and information

obtained on residential fire deaths from a national data base. Cost/benefit

considerations and evaluation of other strategies for life safety are beyond

the scope of this study, but are active areas of investigation at NBS.

2. A REVIEW OF DETECTOR AND SPRINKLER TECHNOLOGY

While detectors and automatic sprinklers were initially developed to

improve property protection in industrial and commercial buildings, they have

subsequently been included in nearly all types of buildings. Major fires such

as the Coconut Grove Night Club fire (1942) and the Our Lady of Angels Grade

O The term residential occupancy is intended to be consistent with the NFPA 901

Uniform Coding for Fire Protection [3], and includes: one and two family

dwellings, apartments, mobile homes, boarding houses, hotels and motels, and

dormitories

.

3
School fire (1958) prompted recognition in the fire community of the need for more effective fire protection strategies for prevention of multiple life loss

fires. An eventual outgrowth of this has been wider use of detection and

automatic sprinklers. Automatic sprinklers have been used to confine the fire

to the room of origin; detectors are installed to provide adequate warning to

persons outside the room to ensure escape or rescue.

2.1 The Role of Detectors and Sprinklers as Design Options for Fire Safety

The principal role of automatic fire detectors is to provide early

warning of a fire, allowing sufficient time for occupants to escape or take

some defensive action before they are overcome by hazardous conditions. While

detectors can also serve to initiate other fire safety devices such as door

closers, suppression systems, and smoke control systems, they can not protect

occupants or control a spreading fire. For life safety, automatic detection

requires that occupants are mobile, or that prompt assistance be available.

Automatic sprinklers provide a means of controlling a developing fire,

providing additional time for escape. In addition, to the extent that hazardous conditions are avoided, occupants could potentially survive the incident

without requiring escape. This capability is particularly important when

occupants are immobile, and rescue is unlikely.

2 .2 Development of Detection Technology

Heat detectors, the oldest form of automatic detection, were initially

the by-product of thermally activated sprinkler heads (late 1800 's). Early

advancements in heat detector technology resulted in two basic types: one which responded at a prefixed temperature threshold and one which responded to

a rate of temperature rise [4]. Heat detectors are best suited for fire

detection in small confined spaces where rapid heat generation can be expected

from a fire, or in areas where environmental conditions are unsuitable for more sensitive detection devices. For many years these two types of heat

4
detectors were considered the industry standard for fire detection in industrial and commercial buildings. And except for subtle changes in design,

these two types are still used extensively in protective signaling systems.

The most significant development in detector technology in terms of

breadth of applicability was the introduction of the smoke detector. Conventional smoke detectors operate by one of two principles, photoelectric or ionization chamber [5]

Photoelectric smoke detectors utilize either light

scattering or light absorption techniques to measure smoke accumulation in a sensing chamber. Ionization chamber detectors utilize a small radioactive

source material to ionize the air in the sensing chamber, rendering it con- ductive, resulting in an electrical current flow between two electrodes.

Smoke which enters the chamber decreases the conductance of the air until a threshold is reached, resulting in alarm.

The notion that smoke would be appropriate as a detection mechanism was

not immediately accepted. The relative high cost, limited availability, and

untested performance deterred the development of smoke detector technology

until results of a series of field tests conducted by the Los Angeles Fire

Department, popularly referred to as Operation School Burning, was published

in 1960 [6] . This was the first well-documented evidence that activation of

smoke detectors preceded heat detectors in most cases. Publication of these

results marked a milestone in the recognition of smoke detector technology,

which has grown rapidly in popularity since 1960.

Heat and smoke detectors have been installed extensively in industrial,

manufacturing, commercial and public buildings, as well as some of the larger

residential and institutional buildings. Generally they are installed as part

of a building-wide alarm system which is also frequently tied into the local

fire department. The purposes of such systems are to provide early warning to

building occupants, and rapid notification of the fire department to reduce

the delay before initiation of fire fighting and rescue operations.

5
2.2.1 Limitations in Applying Commercial Detector

Technology to Residential Occupancies

Commercial heat and smoke detector systems are appropriate for many

residential occupancies (e.g., dormitories, hotels and motels). However,

commercial heat detector systems are less attractive for single family

housing, mobile homes, apartments, and other similar types of residences

because they operate too slowly to provide adequate life safety for many

residential fires, and are prohibitively expensive. Although commercial smoke

detector systems frequently provide significantly earlier detection of fires

than heat detector systems, the cost alone has limited their application in

residential occupancies.

2.2.2 Residential Detection

In response to the need to provide economical, early warning fire

detection for residential occupancies, the fire detector industry developed a "single station" smoke detector. By the mid-1960’s, such devices were available for installation as individual units, rather than as components of the more expensive "systems". In 1967, the National Fire Protection Association

(NFPA) published the first edition of NFPA 74, Standard for Installation,

Maintenance and Use of Household Fire Warning Equipment [7], providing information on types of detectors, operating principles, installation guidelines and

maintenance practices.

The use of "single station" smoke detectors got off to a slow start in

the 1960’s. However, through improvements in design, significant cost reductions, aggressive marketing, and mandatory legislation in local jurisdictions,

residential smoke detectors became readily available during the 1970’ s, providing an economical means of early warning detection for residential occupancies. Figure 3 provides an illustration of the growth of smoke detector usage

in single family dwellings during the 1970’ s. It is estimated that by 1982 up

to 67 percent of the dwellings in the United States had installed smoke

detectors [8] .

6
2.2.3 Field Experience

The life safety impact of commercial heat and smoke detector systems is

not well documented. The use of such systems in industrial and commercial

occupancies to provide warning and rapid fire department response has generally been considered successful. There is anecdotal evidence that such

systems have saved lives in hotels, motels and apartment buildings where large

numbers of people outside the immediate area of the fire were provided sufficient time to escape. Studies such as that conducted by Hall [9] in 1979 have

attributed a number of multiple death fires in apartments, nursing homes and

hotels to the absence of any early warning detection systems.

The life safety impact of single station smoke detectors on residential

fire deaths is somewhat better documented, and has been very encouraging.

Review of the NFIRS data base indicates that the likelihood of death for fires

in dwellings without smoke detectors is 2.5 times higher than the rate in

dwellings with detectors [10]. Recent studies of mobile home fire fatalities

indicate that the death rate is 2-4 times higher in mobile homes without

detectors [11,12].

2.3 Development of Automatic Sprinkler Technology

Automatic sprinkler systems consist of a network of piping with

geometrically spaced nozzles referred to as sprinkler heads. Typically the

piping system is connected to a central water supply and the individual sprinkler heads are activated by heating of a thermal link by the hot gases from

the fire.

Sprinkler systems, first installed in textile mills in the 1850’s, were intended to reduce the likelihood that an entire building or complex would be

destroyed by fire [13]. By 1930, the NFPA Standard for Sprinkler Installation

(NFPA 13) [14] recognized three types of sprinkler systems, based on water

requirements to control or extinguish fires of different magnitudes. These

designations, the "light hazard system", the "ordinary hazard system", and the

"extra hazard system" continue in use today as a basis for design

requirements

.

7
A gradual development in sprinkler technology has followed the initial

design used in the textile mills. The sprinkler head as we know it today was first introduced in 1878 [15]. Most developments up through the 1960's

centered on the water spray patterns, with a major development being the

introduction of the "Standard" sprinkler head in the early 1950's by the

Factory Mutual System [16]. The standard sprinkler was characterized by rede'

sign of the deflector to discharge the water downward, with a uniform

pattern. While other extensions of the technology were introduced, such as

the ultra high-speed sprinklers which were activated by an explosive valve

(1959), and the on-off sprinkler which is capable of shutting itself off, the

basic sprinkler system commonly found in industrial, commercial and public

buildings today has changed very litle since the introduction of the standard

sprinkler head [17].

2.3.1 Limitations in Applying Standard Sprinkler

Technology to Residential Occupancies

As is the case with commercial detection systems, application of

conventional standard sprinkler technology to residential occupancies has been

limited, primarily due to the cost of installation and maintenance of such

systems designed in accordance with NFPA 13. While NFPA 13 sprinkler systems

are found in some hotels, motels, etc., they are not typically required, and

it is uncommon to find such systems in dwellings, mobile homes, and

apartments

.

2.3.2 Residential Sprinklers

New technology was developed in the 1970 's to overcome this barrier to

the application of automatic sprinkler systems to residential occupancies.

The NFPA created a new standard in 1975, the NFPA 13D Standard for

Installation of Sprinklers in One and Two Family Dwellings and Mobile Homes

[18]. While the initial version of this standard relied principally on existing standard sprinkler technology it was recognized that changes in state-ofthe-art sprinkler design would be necessary. Research to provide these

8
changes focused on providing life safety protection for fire hazards unique to

residences, and on system designs which were more economical than the typical

NFPA 13 sprinkler design.

A major source of cost associated with NFPA 13 sprinkler systems is the

water supply. Therefore, initial research [19,20] focused on reducing the

water supply requirements for residential sprinklers exposed to typical residential fires. The results of this initial research disclosed that for

certain fire scenarios typical of fires which occur in residences, standard

sprinklers did not provide adequate life safety with a reduced water supply.

An outgrowth of this research was the introduction of the "residential

rapid response" sprinkler head [21-23]. While similar in appearance to standard sprinkler heads, the residential sprinkler has a thermal link with a much

smaller mass, resulting in quicker activation by a growing fire (figure 4).

The more rapid response characteristics of the residential sprinkler resulted

in suppression action much earlier in a developing fire. Full scale testing

[22] indicated that for many residential fire scenarios, suppression was initiated prior to attainment of conditions hazardous to life safety. In

addition, extinguishment of the fire was achieved with less water demand than

typically required in an NFPA 13 system design.

This has been recognized as the most significant development in sprinkler

technology since the development of the" standard" sprinkler, and demonstrates

considerable promise in terms of reduced costs and improved performance for

residential applications.

2.3.3 Field Experience

While the development of residential sprinkler technology has been too

recent to provide in situ experience, standard sprinkler system performance

has been well documented. In non-residential occupancies, the average property loss from fires is far less when sprinklers are installed. For example,

in a six year study of mercantile buildings by Factory Mutual Research

Corporation (FMRC) a property loss-per-fire ratio was found to be 10-

to-1 between unsprinklered and sprinklered buildings [24]

9
Other studies, though limited in terras of the size of the data base and

the specialized nature of the occupancies, also provide some evidence of the

impact of sprinklers on property losses. A nine year study of U.S. Army

supply warehouses reported a property loss-per-f ire ratio of 107-to-l for

unsprinklered and sprinklered warehouses [25] . Studies of Navy and Marine

warehouses [26], and U.S. Department of Energy (DOE) facilities [27] reveal

similar benefits.

Substantial evidence of the reduction in property losses due to sprinkler

systems is available. In addition, limited information on the impact on life

safety is reported in the literature. A prominent New Zealand/ Australian

survey reported only five deaths over 90 years in 5,734 fire incidents where

automatic sprinklers were present [28]. In addition, a DOE study which

spanned a period of 28 years (1952-1980) reported no fatalities in sprinklered

DOE facilities [27]. These statistics, along with NFPA records which indicate

that there have been no multiple life loss fires in sprinklered buildings in

the U.S [29], offer evidence that sprinklers have an impact on life safety.

However, the magnitude of the impact is difficult to discern when one con- siders that most fire fatalities occur in residential occupancies one and two

at a time (refer to section 1), the above statistics have limited relevance.

Less than three percent of the cases in the New Zealand/Australian study and none of the DOE cases involved residential occupancies. In addition, there were no fatalities in any DOE facilities over the period studied, whether or not sprinklers were installed. Therefore, the information should be treated

as anecdotal, but certainly encouraging.

3. MAJOR FACTORS IN ESTIMATING POTENTIAL

EFFECTIVENESS FOR RESIDENTIAL LIFE SAFETY

Field experience indicates that the significant benefits that have been

derived from the use of conventional detection and standard sprinkler technology in averting multiple life loss have resulted largely from protection of

persons outside the room of fire origin. However, most fire deaths in residential occupancies occur in ones and twos, many of them either from immediate

exposure to small, slow developing fires, or intimate exposure to clothing or bedding fires.

10
Smoke detectors can provide adequate time to escape for many cases. But

in those cases where occupants are intimately exposed to the fire, or immobile

and therefore unable to escape, a smoke detector may have little or no benefit. As an example, in a study of 342 fatal residential fires conducted

by McGuire and Ruscoe [30] in 1962, it was concluded that up to 41 percent of

the deaths could have been averted by smoke detectors. The remaining 59

percent of the deaths could not have been prevented by smoke detectors alone

because the occupants were immobile, intimate with the fire, or exposed to

very rapid fires (e.g., flammable liquids). An ongoing study at NBS [31]

indicates similar limitations in smoke detector performance.

The field experience with standard automatic sprinklers demonstrates a high level of success in reducing the number of fatalities in various occupancy types. Field experience also indicates that standard sprinkler systems

are less effective for individuals located in the room of fire origin, particularly in residential occupancies where small volume rooms permit rapid development of hazardous conditions. In these cases, the inherent delay in system

activation due to the thermal lag of the sprinkler heads* sensing element

results in generation of hazardous conditions prior to initiation of suppression action. A 1974 report from the State of Oregon indicated that nine of 13

deaths in Oregon nursing homes had occurred in sprinklered buildings [32]

.

All nine fatalities were single patient fatalities in which the person died in

the room of fire origin, before the sprinkler system was activated. A review

of 1976-79 NFIRS data by NBS [33] indicates that 35 percent of all single

fatality nursing home fires occurred in sprinklered buildings. And, current

NBS estimates for dwelling fires indicate that up to 36 percent of the fatalities occur to occupants who are in the room of fire origin and possibly intimately exposed (e.g., clothing ignition) to the ignition [34].

Although, there is little field experience with rapid response

residential sprinklers, results of full scale experiments indicate that a significant portion of those residential fatalities that may be unsavable with

standard sprinklers due to the inherent delay in sprinkler head activation may

be adequately protected by residential sprinkler technology [22,23,35,36]. As

illustrated in figure 5, results of full scale fire tests show that devices

demonstrating the thermal response characteristics of residential sprinklers

11
o can in most cases activate before hazardous conditions are reached in the room of fire origin. Although people who are intimate with the fire may

remain unsavable, those who are not intimate with the fire but are in the room

may survive, whether they are immobile or not. NBS estimates [31] indicate

that many one and two family residential fire deaths and injuries could be

averted by the quicker responding residential sprinklers alone. And, residential sprinklers in conjunction with smoke detectors could potentially provide

an even greater reduction in residential fire fatalities and injuries.

This discussion suggests that both the performance benefits and the

limitations of detector and sprinkler devices can have a significant impact on life safety expectations. Therefore, any estimate of the impact of detector

or sprinkler technology on fire fatalities in residential occupancies requires

consideration of key factors which affect the performance. Such factors

include

(1) the major fire hazard scenarios

(2) the location and capabilities of the occupants

(3) the response time of detector or sprinkler

(4) the effect on the development of hazardous conditions

3.1 Dominant Residential Fire Scenarios

Gomberg, Buchbinder, and Offensend [43] performed a detailed analysis in

which residential fires were grouped under nine major scenarios. For purposes

of this study the major fire scenarios identified by Gomberg, et al. can be

classified by location of ignition, and fire growth characteristics. That is,

oJWhile the state-of-the-art does not permit a precise assessment of the direct

hazard to humans of exposure to fire conditions, a number of studies provide

estimates of levels at which adverse effects occur [37-42] . In this study,

estimates of hazardous levels of gas temperature, carbon monoxide, oxygen and

smoke density were selected based on review of these studies. These levels,

which are considered approximate, are:

Temperature > 100°C

Carbon Monoxide > 8,000 ppm or 50% COHb

Oxygen < 12% by volume

Smoke Density > .25-. 50 OD/m

12
ignition locations include: (1) outside the dwelling; (2) inside the dwelling,

but within a concealed space, and (3) within a room. Fire growth is separated

into three groups; smoldering/ flaming , flaming, and fast flaming. These three

characteristic fires provide sufficient variation in fire development to

reasonably represent abroad range in typical residential fires, including the

four major causes of residential fire fatalities, i.e., smoking

( smoldering/ flaming) , cooking (flaming), heating (flaming) and

incendiary/suspicious (fast flaming).

The growth characteristics of these three types of fires are illustrated

in figure 6. Smoldering/flaming fires, including ignition of furniture by

smoking materials, are characterized by a long early growth period where only

a slight increase in room temperature and slow emission of combustion products

occur. Flaming fires may include furniture ignitions as well as other

incidental ignitions, resulting in immediate flaming. This type of fire is

characterized by a shorter early growth period, during which combustion

products adverse to life safety are usually given off in greater quantities

than in smoldering fires. Flaming fires also are accompanied by a higher

temperature rise during early growth. Fast flaming fires are characterized by

almost no early growth stage. Such fires typically include incendiary/ suspicious fires, or those involving flammable liquids, gases, or explosives, and

enter the transition stage leading to a fully developed room fire very

quickly. In addition, shielded fires such as concealed space or closet/wardrobe fires may also be characterized as fast flaming.

3.2 Location and Capability of Occupants

For purposes of this study, three situations were identified which

describe the location of an individual with respect to his/her exposure to a developing fire. One situation involves those persons who are intimate with

the ignition. Typical examples include clothing ignitions and bedding or upholstered furniture fires where a person is directly exposed to the fire.

The second situation includes persons who are in the room where the fire

starts, but are not directly exposed. The third situation includes persons

who are outside the room of fire origin at ignition.

13
In addition to location, the capabilities of the individuals in terms of

their ability to escape are important. Therefore, consideration was given to

whether or not the individual is awake or asleep, and whether or not they are mobile or immobile. For purposes of this study, immobile includes the very

young or very old, and the physically or mentally impaired, including impairment from drugs or alcohol.

To systematically examine the possible combinations of factors which

represent the dominant cases for fatal fires in residential occupancies, a parametric model was constructed (figure 7). Appropriate combinations of the

fire scenario parameters (fire type, fire location) and the occupant location

and capability parameters (location, status) can be readily selected for

consideration of detector or sprinkler effectiveness. The scenarios examined

in this study are representative of most residential fire fatalities.

3.3 Response Time

As discussed in section 2, smoke detectors respond to an accumulation of

smoke particulate within the devices' sensing chamber. In a developing fire,

the response will depend on a complex interrelationship of environmental

factors such as fire size and growth rate, fuel type and smoke generation

rate, room geometry and ventilation, and detector characteristics such as location, smoke entry characteristics and predetermined detector sensitivity

thresholds. Sprinkler heads, activated by a thermal sensing element, are affected by similar environmental factors such as room size, ventilation rate,

and the rate of heat release of the fire, and by location in the room, as well

as the temperature and the heat transfer characteristics of the sensing

element

While the rate of temperature rise and smoke production are both

functions of the rate of fire growth, quantities of smoke sufficient to activate a smoke detector generally precede a gas temperature sufficient to

activate a sprinkler. Therefore, considerable differences in response time

can occur between smoke detectors and automatic sprinklers as a result of

differences in the sensing medium. A conceptual illustration is provided in

figure 8.

14
Extensive research has been conducted to develop quantitative methods to

predict the response characteristics of detectors and sprinklers, and their

performance in compartment fires [44-47]. Good progress has been made, but in

order to permit generalized calculations of detector or sprinkler response for

a wide range of environmental conditions, these models must be expanded in

scope to provide a more complete account of variations in the physical pro- cesses associated with compartment fires. Work is continuing in this area to

provide and validate such generalized models.

3.4 Impact on Development of Hazardous Conditions

Figure 9 provides a simple graphical illustration of the primary role of

smoke detectors, to alert occupants and provide sufficient time for escape. A

simple expression has been proposed by Cooper [48] as a means of analytically

describing this process:

T < T - T

E - H D

where

Tg = time required to escape

= time to reach hazardous condition

T

d

= time to detection

The behavior of a smoke detector can have a substantial effect on escape time, even though it can't directly affect the growth of the fire. For example, a more rapid response, which can be accomplished by increasing detector sensitivity, or decreasing spacing, will increase the time available for escape.

A sprinkler system can have a direct impact on the development of the

hazard (figure 10). The level of success of a sprinkler system in controlling

hazardous conditions depends on when the system is activated, the capacity of

the system to suppress or extinguish the fire, and the effects of other design

features. Research is active in these areas, but it will be some time before

these factors are adequately understood to permit accurate, quantitative

prediction of their effects on hazard development for generalized cases.

15
In the absence of methods to predict the performance of a particular

detector or sprinkler device, large scale experimental studies have been

conducted to provide estimates. While such studies are not comprehensive in

terms of examining the interrelationships of the key parameters outlined

above, the results of these studies provide insights regarding performance. A

brief review of selected studies is presented in the following section. The

results of these studies provide the basis for estimates used in this study on

the impact of detector and sprinkler technology on fire fatalities in residential occupancies.

4. REVIEW OF SELECTED FULL SCALE STUDIES

In recent years CFR has supported full scale experimental studies

designed to examine the life safety benefits of selected design strategies,

including detectors and automatic sprinklers. These studies have provided

experimental measurements of detector response times, sprinkler activation

times and the impact on the development of hazardous conditions from typical

room fires for geometries representative of mobile homes, single family dwellings, and hospital patient rooms. The studies of geometry and environmental

conditions in the patient room also provided insights into the expected performance of detectors and sprinklers in other residential occupancies such as hotels, motels and apartments. The results of these studies provide some of

the information necessary to estimate the performance of detector and sprinkler devices under conditions representative of actual fires in residential

occupancies

4.1 Mobile Home Studies

Full scale studies conducted by Budnick and Klein [38,49] provide

quantitative measurements of the development of hazardous conditions in typical mobile home structures from incidental^ fires. In these studies hazardous

conditions developed almost uniformly throughout those portions of the space

^An incidental fire is a typical residential fire which intially involves a single item or small fuel package, but if unimpeded, will spread throughout

the room, and beyond to adjacent spaces [50].

16
open to the room of fire origin. Therefore, in considering life safety, the

available time before hazardous conditions were reached was nearly the same throughout the structure, unless the occupant was behind a closed door.

The development of hazardous conditions is dependent on the rate of fire

growth, and the impact of a particular detector or sprinkler on life safety

will be substantially affected by that rate. In figures 11 and 12, ceiling

temperature in the room of origin is plotted continuously for two tests con- ducted by Budnick and Klein. The times at which thresholds for hazardous

conditions were reached, based on the criteria presented in section 3, are indicated on the plots, along with the response times for smoke detectors used

in the experiments. In addition, estimates of activation times for a 135°F

fixed temperature heat detector, a residential rapid response sprinkler

(RTI ~ 41) '’and a standard sprinkler (RTI ~ 100) are provided^.

Test 10 (figure 11) is characterized by a short incipient fire growth

period, followed by transition to rapid flaming. The short incipient growth

period provided a limited amount of time for escape or defensive action, and

the inherent delay in thermally activated devices such as heat detectors or standard automatic sprinklers would provide marginal life safety benefits.

However, even for this type of fire where hazardous conditions were reached

quickly, the residential smoke detector responded in sufficient time to provide more than three minutes of escape time. It was also estimated that the

residential sprinkler would have activated before transition to rapid fire

growth, preventing the development of hazardous conditons.

The response time index (RTI) for thermally activated links:

RTI (m

1//2 s 1/2

) = x v^T

g

-t

act g

in (lAT

act)

AT

see reference [51]

£ The RTI values of 41 and 100 were selected as typical for residential and

standard sprinklers. It should be recognized that significant variations

occur in RTI values among the many sprinkler heads commercially available.

17
In test 11 (figure 12), the incipient fire growth period was much longer,

characteristic of a smoldering or slowly developing flaming fire. While a smoke detector provided an extended period for escape time (T^ - > 8

minutes), the very low temperature levels would have delayed the operation of

a heat detector or a residential sprinkler considerably, resulting in a limited impact on life safety. The greater thermal lag for a standard

sprinkler (RTI ~ 100 to 300) would have delayed activation until transition to

rapid fire growth occurred, and hazardous smoke levels were exceeded.

In these two tests smoke detectors provided the earliest warning, and

therefore the maximum time to escape, provided that the occupant is mobile,

and not intimate with the fire. Residential sprinklers and heat detectors

activated in the room of fire origin at about the same time, and before the

onset of hazardous conditions. However, the delay associated with the thermal

lag of the heat detector reduced the escape time significantly. The low

temperature levels resulting from a slowly developing fire may delay the

response of a residential sprinkler, allowing hazardous levels of smoke and

toxic gases to be approached or exceeded before suppression is initiated.

The inherent thermal lag of a standard sprinkler would have resulted in

delayed activation until transition to rapid fire growth occurred, and hazardous conditions were approached. Therefore, the life safety benefit to

occupants in the room of origin, and in communicating spaces open directly to

the room would be marginal.

Bukowski [52] also conducted full scale tests in a mobile home to study

environmental effects on smoke detector response. His results for flaming

upholstered chair fires are consistent with results reported by Budnick and

Klein. Figure 13 illustrates the early response of the smoke detectors, and

the subsequent response of the thermally activated devices. As in the earlier

study, the 135°F fixed temperature heat detector and the residential sprinkler

would have activated before hazardous conditions were reached, but the heat

detector would provide considerably less escape time than that provided by the

smoke detectors. The test fire was manually extinguished before a standard

sprinkler would have activated.

18
Bukowksi also conducted smoldering upholstered furniture fires. Figure

1A illustrates the results of a typical smoldering test, characterized by an extended incipient burn period, followed by rapid transition to flaming.

While smoke detectors activated during the incipient period - providing

extended escape time, the thermally activated heat detectors and sprinklers

would not have activated until rapid flaming occurred. Although a residential

sprinkler would most likely have extinguished the fire, hazardous levels of

smoke were reached long before it would have activated. The rapid deterioration in conditions following transition to flaming would have seriously

threatened the lives of immobile or unaware occupants close to the fire. A

standard sprinkler would have activated soon after the residential sprinkler,

but the very rapid fire growth following transition to flaming would most

likely result in untenable conditions by then.

A. 2 Dwelling Studies

CFR funded a major series of full scale tests [53] in the mid-1970's to

provide field data and performance criteria for the installation of

detectors. The results of this experimental work served as the basis for

current installation requirements for residential detectors in NFPA 7A. The

results of these tests provide insight into issues of life safety in residences and the effects of heat and smoke detectors.

The tests were conducted in a one story and in a two story dwelling. Gas

temperatures, carbon monoxide, oxygen depletion, and smoke density were monitored throughout the dwellings, particularly along the escape paths, for a variety of flaming and smoldering fires. The adequacy of detectors positioned

at different locations in providing minimum required escape time (estimated by

the investigators at 2 minutes) was assessed. The results indicated that a smoke detector must be located on the story (e.g., floor) where the fire

starts in order to provide adequate escape time. It was found that heat

detectors in the room of fire origin provided little or no escape time.

Figure 15 illustrates the success frequency, defined as the frequency

where a minimum of two minutes of escape time was achieved, when a smoke

detector was located on each floor of the dwelling. In every case the smoke

19
detector alarmed before hazardous conditions were reached in the room of fire

origin, along the escape path, or in remote rooms. In greater than 90 percent

of the cases, the escape time provided was greater than two minutes, the

minimum value set for this study. Assuming that occupants are mobile, not

intimately exposed to the fire, and an escape time of two minutes is sufficient, smoke detectors installed on every level of the dwelling provided

adequate protection for escape for all the test fires conducted in this

series

.

The success frequency for heat detectors located in the room of origin is

shown in figure 16. These results indicate that a minimum escape time of two

minutes was provided in 60 percent of the flaming tests, and 25 percent of the

smoldering tests. For a number of tests, hazardous conditions were exceeded

before the heat detector responded, rendering marginal or no life safety

benefit to the occupants.

CFR and USFA jointly sponsored a series of full scale dwelling tests in

1979 in Los Angeles, CA [54,55] to determine the performance requirements for

newly developed residential sprinkler technology (RTI ~ 41). The tests were conducted in a large, two story dwelling which was instrumented to measure the

development of hazardous conditions in the rooms and along the escape routes.

While no data were obtained on detector response in the Los Angeles test

series, extensive data were collected on gas temperatures and toxic gas production - both before and after sprinkler activation. Peak levels for eye

level temperatures, carbon monoxide and oxygen concentration (table 2)

indicate that hazardous conditions were not approached in the room of fire

origin, at the top of the stairs, or in the bedroom on the second floor for

both smoldering and flaming upholstered furniture fires initiated in the

living room. The residential sprinkler responded before hazardous conditions

were approached, successfully extinguishing the fire and maintaining tolerable

levels of temperature, CO and O

2 in the room of origin, and throughout the

dwelling.

The results from these living room upholstered chair fires are typical of

the performance of the residential rapid response sprinklers for most of the

20
scenarios tested. Two exceptions were (1) a flaming fire in an unsprinklered

walk-in closet in a bedroom and (2) a smoldering fire in a closed bedroom. In

both of these cases, a residential sprinkler was located in the bedroom.

Comparison of ceiling gas temperatures for tests with and without a residential sprinkler installed in the closet (figure 17) indicate a dramatic difference in performance. In the test where the closet was sprinklered, minimal

increases in temperature and CO resulted throughout the dwelling. In the test

where the closet was not sprinklered, hazardous conditions were substantially

exceeded in the bedroom, along the escape path, and in the living room. Table

3 provides a comparison of peak values.

In the smoldering mattress bedroom test where the bedroom door was left

open, providing ventilation, the residential sprinkler extinguished the fire,

and hazardous conditions were not approached. As indicated in figure 18, the

sprinkler activated shortly after transition to flaming, which was accompanied

by an increase in gas temperature at the sprinkler.

In the test where the bedroom door was left closed, the fire did not

reach a flaming state. As a result, although the residential sprinkler even- tually activated (more than five hours after smoldering ignition) and

controlled the fire, CO concentrations exceeded 5000 ppm (the maximum range of

the CO analyser) more than two hours prior to sprinkler activation. Such a concentration for that time period would be considered lethal.

For the tests reviewed, residential sprinklers controlled flaming fires

typical of many of those that occur in residences. In most of these typical

scenarios, the sprinkler activated before hazardous conditons were reached in

the room of fire origin and maintained tolerable conditions throughout the

space. However, in some, such as unsprinklered flaming closet fires and

smoldering fires, hazardous conditions were reached, even with the more rapid

responding residential sprinklers.

4.3 Health Care Room-Corridor Studies

CFR conducted a full scale test program to evaluate the performance of

detectors and sprinklers in hospital rooms. The tests were conducted in one

21
of CFR's room-corridor facilities, and involved flaming ignition of mattresses

(flaming fire scenario) and wardrobes (shielded fast flaming fire scenario),

simulating fires in patient rooms adjacent to a corridor.

Detector studies [56] provided comparisons among ionization and

photoelectric smoke detectors and heat detectors at different locations in

terms of alarm times and available escape time. Figure 19 shows the average

and the range of estimated available escape times (1) from the room of fire

origin, and (2) along the escape path in the corridor for the complete series

of burns. Consistent with previous work, it was found that smoke detectors

provided the maximum escape time. Smoke detectors in the corridor provided

three to four minutes of escape time from the room, and along the corridor.

Heat detectors in the room provided an average escape time of one minute from

the room and two minutes along the corridor. However, in some of the tests

the hazardous threshold for smoke obscuration was reached in the room prior to

activation of the heat detector.

O'Neill, Hayes, and Zile conducted studies of sprinkler performance in

the same facility [57]. The thermal response characteristics of both standard

and residential sprinklers were examined. In tests with flaming ignition of

mattresses, a simulated residential sprinkler activated prior to attainment of

hazardous conditions, extinguished the fire, and maintained survivable conditions in the room of fire origin. However, in tests with the somewhat slower

standard sprinkler, smoke concentrations exceeded the hazard threshold in the

room, along the corridor, and in the remote lobby area prior to sprinkler

activation. Figure 20 provides a comparison of the impact of the residential

and standard sprinkler activation relative to attainment of hazardous conditions both in the room of fire origin and along the corridor. Figure 21

illustrates a substantial difference in the height of the smoke layer in the

patient room doorway at the time of activation for the two sprinklers. For

the standard sprinkler the smoke layer would have reached bed level. (This

does not take into account the mixing effect of the sprinkler spray on the

smoke distribution after initiation of suppression.)

In tests with combustible wardrobe fires, little difference was observed

in the response time for the two sprinklers. Figure 22 illustrates the rapid

22
fire growth rate resulting from the shielded wardrobe fire. As would be

expected, for such a rapidly developing fire, the relative difference in

activation time between the residential and the slower standard sprinkler is

smaller. However, test results indicated that hazardous conditions were reached at approximately head level (1.5 m above floor) in the room, corridor

and lobby before either sprinkler activated.

These health care room-corridor studies indicate that for typical flaming

fires (e.g., mattresses) a residential sprinkler can provide protection to

occupants both inside and outside the fire room. A heat detector may provide

marginal escape time in some instances, but smoke detectors provided superior

performance, providing at least two minutes of escape time in all of the cases examined.

In the case of severe, fast flaming shielded fires such as those from

burning wardrobes or unsprinklered closets neither a standard nor residential

sprinkler would respond rapidly enough to prevent hazardous conditions from

being reached throughout the space, and a heat detector would provide essentially no warning. Although no smoke detectors were present for the shielded

wardrobe tests, the rapid development of the fire indicates that smoke detectors would provide marginal or no escape time, particularly from the room of

fire origin. While these studies were directed at health care occupancies,

the results are somewhat relevant to residential occupancies of similar geometry such as hotels, motels and apartments.

4.4 Implications of Experimental Results for

Residential Life Safety

The results of these full scale studies provide some insight to the

potential role of detection and sprinkler technologies on residential life

safety. For example, smoke detectors installed in accordance with current

practices (NFPA 74) virtually always provide substantial escape time. The

amount of time is dependent on the geometry of the structure and the growth

rate of the fire, but a minimum escape time from the room of fire origin of

23
two minutes^ was usually exceeded under the conditions tested. Heat detectors

located in the room of origin provided marginal escape time under some of the

fire scenarios tested, but demonstrated no apparent advantages over smoke

detectors. For many fires, hazardous conditions were approached or exceeded

before the heat detector activated. This was particularly true for smoldering

fires

Sprinkler systems can make an important contribution to residential life

safety; namely they provide immediate action to control or extinguish the

fire. This capability is particularly important when occupants are not able

to escape, and therefore must be protected while remaining in the dwelling.

In the studies reviewed, a standard sprinkler (RTI ~ 100) controlled or extinguished the developing fire, and usually provided escape time from locations

outside the room of fire origin. However, for many of the fires, hazardous

conditions were reached in the fire room prior to activation of a standard

sprinkler, providing only marginal protection to occupants in the room.

Except for tests involving smoldering fires or unsprinklered flaming

closet fires, the residential sprinkler (RTI ~ 41) activated much earlier than

the standard sprinkler, generally before hazardous conditions were reached in

the room of fire origin. For many of these cases the fires were extinguished

and survivability in the fire room appeared likely, unless the occupant was intimately exposed to the fire. In the fire tests involving unsprinklered

closet fires and smoldering upholstered furniture fires, hazardous conditions were reached prior to operation of the residential sprinkler, resulting in

limited life safety protection in the room of fire origin and along primary

escape paths.

These full scale tests pointed out limitations in the impact of detectors

and sprinklers for selected geometries and conditions. For example, in small

volumes typical of mobile homes, ramblers, apartments and other single-story

conventional residences, hazardous conditions develop throughout the comrauninumber of the references selected two minutes as a minimum escape time

needed for residences. This value is used here only for discussion purposes;

the actual escape time needed depends on factors such as condition and

mobility of the occupants and required travel distances to safety.

24
eating spaces at nearly the same time. Therefore for such structures it may

be necessary to assume that the entire volume is the room of fire origin in

determining the required escape time and selecting a design strategy. The

addition of a barrier such as a wall or closed door to provide physical separations within the residence can increase the escape time provided by a detector or sprinkler alone.

A smoldering fire in a closed room without a smoke detector presents a hazard to the occupants of the room. Smoke detectors installed in accordance

with current criteria (typically located in halls and stairwells) will not

activate before hazardous conditions are reached in a room with the door

closed.

Finally, current installation criteria for residential sprinklers are intended to provide sprinkler coverage in rooms of most probable fire origin,

as indicated by residential loss experience. Complete sprinkler protection of

a dwelling including bathrooms and closets appears impractical from a design

and economic standpoint. However, if a fire occurs in a space that isn't protected, it may result in a different, more demanding challenge on the sprinkler system. For example, in flaming tests in closets which were not sprinklered, hazardous conditions occurred along the escape path and in other rooms before the residential sprinkler in the adjacent bedroom controlled the

fire. Therefore, reliance on a residential sprinkler to provide protection to

occupants who can not escape would be inappropriate for these conditions.

Tables 4a, 4b, and 4c summarize the effect of detectors and sprinklers on

the three fire types and various occupant locations and capabilities discussed

in section 3. These estimates are based primarily on the results of the full

scale studies reported here. Since heat detectors consistently provided less

time for escape than smoke detectors, and frequently provided no escape time,

they are not included. It should be noted that this paper addresses life

safety from fires in habitable areas considered the most probable areas of

fire origin. While heat detectors provided marginal or inadequate escape time

for many of the cases studied, their use for protection of uninhabited areas,

such as garages and attics, where temperature and humidity conditions vary

substantially, is appropriate.

25
For each combination of fire growth type and occupant status, an assessment is made of the ability of a residential smoke detector to provide

at least two minutes of escape time, and a standard sprinkler or a residential

sprinkler to activate and extinguish the fire prior to the development of

conditions that will result in death or serious injury to the occupant.

In table 4a, assessments are provided for the likely impact of smoke

detectors and sprinklers on smoldering/ flaming fires. For the analysis con- ducted, it was assumed that persons in the room of fire origin who were awake

and mobile would react prior to detection of the fire by the smoke detector or extinguishment by the sprinklers, therefore reducing the need for these

devices for this particular case. It is recognized that one can not

accurately predict that correct behavior would result on the part of the

occupant. In lieu of a detailed examination of this, in those cases where

incorrect behavior would lead to a fatality, it is assumed that the occupant

is actually immobile for purposes of this analysis.

Based on review of the results from the full scale studies included in

this paper, it is expected that a smoke detector, a residential sprinkler or a standard sprinkler will provide protection to mobile occupants outside the room of fire origin. Immobile occupants would be protected by either sprinkler; a smoke detector would have little benefit without rescue. For occupants located in the room of fire origin, the extent to which protection is

provided is greatly influenced by their status. For example, a smoke detector

would provide the minimum escape time for occupants in the room who are awake

or asleep, but mobile. And, while a residential sprinkler responded before

hazardous conditions were reached in the room of origin in some of the tests

reviewed, this was not the case for the smoldering/ flaming tests in mobile

homes, or in the closed door bedroom tests. Therefore, it was concluded that

residential sprinklers would provide some, but not complete protection for

occupants in the room of fire origin who are exposed to a smoldering/ flaming

fire. The test data suggest that the delay in response of the standard

sprinkler to smoldering fires would result in hazardous conditions in the room

of origin before initiation of suppression, therefore providing little

protection to occupants in the room.

26
The assessments provided in table 4b for flaming fires indicate similar

protection to that for the smoldering/flaming condition for occupants outside

the room. For occupants located in the room of fire origin, the test results

indicate that the residential sprinkler would respond very quickly to this

type of fire growth behavior, initiating suppression action before hazardous

conditions were approached and protecting occupants in the room, regardless of

their status. As in the case of the smoldering/ flaming fire, awake/mobile

occupants who might react irrationally - resulting in a fatality, were con- sidered immobile.

Table 4c provides assessments of the impact of smoke detectors,

residential sprinklers and standard sprinklers for fast flaming fires. The

full scale tests in this review included rapidly developing shielded wardrobe

and closet fires. The extremely limited data from these tests indicate that

smoke detectors may provide limited protection to mobile occupants outside the room of origin. However, hazardous conditions were exceeded both in the room

of fire origin and at multiple locations outside the room before either a standard or residential sprinkler would have responded. Also, due to the

shielding of the fire from the sprinkler water spray, extinguishment was not

always readily attained.

While the results indicate that detectors and sprinklers provide very

limited benefit for the shielded fast flaming fires included in this study,

the benefits may be considerably greater for other types of fast flaming

scenarios. For example, Cote [58] reports rapid extinguishment of fast developing flaming fires initiated with various quantities of flammable liquids.

These fires, conducted to simulate hotel arson/incendiary fires, resulted in

marginally hazardous smoke conditions in the immediate area of the fire, but

extinguishment by the residential sprinklers resulted in low temperature and

toxic gas levels. This indicates that the assessments provided in table 4c

should be primarily limited to shielded, rapidly developing fires. Significant benefits may be derived from both standard and residential sprinklers for

other fast flaming scenarios such as flammabile liquid spill fires.

The tables illustrate our lack of data on the exposure of persons who are intimate with ignition. In addition, the experimental data indicate that none

27
of these strategies will protect occupants who are Intimately exposed to a shielded fast flaming fire, but some benefit may be expected In smolderlng/f laming and flaming fires.

5. QUALITATIVE ASSESSMENT OF DETECTOR AND

SPRINKLER EFFECTIVENESS

5.1 Assessments

The analysis of full scale test data presented In section 4, and a review

of residential fire loss experience, can be used to estimate the potential

effectiveness of detector and sprinkler technology In providing adequate life

safety in residential occupancies. Also this assessment Identifies limitations and gaps In available data.

The assignments In tables 4a, 4b and 4c from section 4 were used to

estimate the potential benefit of a smoke detector, a standard sprinkler, or a residential sprinkler In protecting against the dominant fatal scenarios for

residential occupancies. Table 5 summarizes the results of this analysis.

The six dominant scenario groups listed In table 5 represent those fatal

fire scenarios which most frequently occur in one and two family dwellings,

mobile homes, and apartments. The data on scenario groups and fatalities were obtained by analysis of the 1980-81 NFIRS data base [2].

The characteristics of the scenario groups correspond to the fire and

occupant parameters discussed in section 3. Figure 23 illustrates the specific parameters to be considered for scenario group #1, based on the possible

combinations developed in the parametric model presented in section 3. The

appropriate combinations also were identified for the remaining groups.

A strategy was considered to provide protection if, by itself, it would

most likely provide a sufficient level of safety to prevent a fatality under

that particular scenario group. Some interesting observations can be made

based on the information presented in table 5. For scenario group #4, where

mobile occupants died outside the room while asleep, a smoke detector is the

28
most effective strategy if one is concerned with protecting these occupants

from all three fire types (i.e., shielded fast flaming, flaming, smoldering/flaming). While detectors, standard sprinklers and residential sprinklers

all can be expected to provide protection for flaming fires, some limitations

exist in the protection provided by standard or residential sprinklers due to

the delay in responding to smoldering/flaming and shielded fast flaming

fires. This scenario group accounts for nearly half of the fatalities in one

and two family dwellings and mobile homes.

For the six major fire scenario groups included in this study, table 5 indicates that a combination of smoke detectors and residential sprinklers

could provide the maximum protection among the various combinations of smoke

detector, standard and residential sprinkler examined. If it is assumed that

the smoke detector and residential sprinklers are totally adequate and reliable, then the combination of smoke detectors and residential sprinklers could

reduce fatalities by as much as 73 percent in dwellings (scenario groups #2,

#4, and #5). Similar benefits could be derived for mobile homes and apartments. Due to the assumption of total adequacy and reliability, the 73

percent reduction in fatalities may represent an upper bound estimate.

While the largest impact would result from the combination of smoke

detectors and residential sprinklers, other combinations could also provide

significant impact. For example, it is estimated that standard sprinklers in

combination with smoke detectors could reduce fatalities by as much as 57

percent in dwellings (scenario groups #4 and #5).

The second most frequent scenario group was #1, involving occupants who

are intimately exposed to the fire. The lack of a detailed understanding of

the effects of fires on occupants who are intimate with ignition, or the

performance of a detector or sprinkler on a concealed space fire limit our ability to assess the protection provided by these strategies for such residential scenarios. But intuitively, one must assume that the performance

characteristics of state-of-the-art detection and sprinkler technology would

have very limited impact on such fire deaths.

29
The limited test results available for shielded fast flaming fires

indicate that it is unlikely that smoke detectors or sprinklers will provide

protection to occupants located in the room of fire origin. It would appear

that scenario group //3, which includes the fewest number of fatalities for the

six major scenario groups, could not be adequately protected by any combination of these state-of-the-art smoke detectors and sprinklers. While this

does not consider the impact of smoke detectors and sprinklers on fatalities

from unshielded, fast flaming fires, the NFIRS incident data base used to

identify the major scenario groups included only a few fatalities resulting

from such fires. The majority of the fatalities included in scenario group //

involved shielded fast flamming fires.

The results in table 5 for scenario groups //I and //3 indicate that on the

order of 20 to 30 percent of the fatalities in these residential suboccupancies may be unsavable by either detectors or sprinklers.

The NFIRS data base contains only a limited number of fatal fire

incidents for large residential occupancies such as dormitories, hotels and

motels, board and care, and institutional. However, the majority of fatal

fire incidents in these suboccupancies result in one or two deaths, with the

dominant scenarios similar to those of dwellings, mobile homes, and apartments

[2]. If it is assumed that detectors and sprinklers would perform in a similar manner in these suboccupancies, the same benefits could be expected.

Also it is likely that detectors and sprinklers would decrease the number of

multiple-fatality fires. While these fires occur very infrequently, they

generally receive a great deal of public attention.

5.2 Limitations of the Assessments

The results of the assessments in section 5.1 indicate that smoke

detectors and residential sprinklers could have a significant impact on residential fire deaths. These results are based on analysis of a limited number

of full scale experiments and statistical loss data from the NFIRS data

base. The estimates are also based on the assumptions that the devices will

be installed correctly, will be maintained, and will perform adequately and

reliably.

30
The adequacy of the devices was partially based on analysis of the

experimental studies. The extent to which these studies accurately reflect

the universe of residential fire death incidents, and the validity of the

extrapolations performed in the assessment can only be determined through more

rigorous quantitative methods.

The reliability of detectors and residential sprinklers depends on factors such as the performance limits of the mechanical and electronic com- ponents, the installation, and adequate maintenance. In addition, environmental factors such as variation in hazard development (e.g., the effect on smoke generation and transport) or variations in system parameters (e.g.,

changes in system water pressure) can potentially alter the reliability or adequacy of the device.

Finally, in addition to considerations regarding adequacy and

reliability, the assessment excludes any considerations of cost/benefit, or social issues such as individual risk perception and acceptability of the

technology. These factors, while beyond the scope of this paper, are essential in successful implementation of any strategy to improve fire safety.

6. TOWARD APPLICATION OF QUANTITATIVE TECHNIQUES

Quantitative measures of the performance of detectors or sprinklers under

varying conditions would improve the estimates presented in table 5. This can

be done using analytical models which mathematically describe the function of

these systems for a broad range of cases, and a series of carefully planned

and executed experimental studies to validate the models and test their

results.

NBS has been engaged in research to develop analytical methods to predict

room fire growth, and multiple room fire spread [59,60]. An extension of

these efforts that will provide the quantitative basis for determining the

performance of detectors or sprinkler systems in residential fires has

recently been initiated. The objective of this work is to provide analytical

methods useful in increasing the ability to predict effectiveness of these

systems in reducing residential deaths and injuries. This broader context

31
includes consideration of occupant needs, hazard development, and the

performance of other fire safety strategies as well as detectors or sprinklers. This approach requires an understanding of the physical processes

involved and their functional interdependencies.

A parametric framework or model is under development at NBS which can assist in addressing residential life safety from this broad, comprehensive

viewpoint. The initial version of this model (figure 24), while incomplete,

identifies many of the conditions or factors to be considered for residential

life safety, including detection and suppression. The model, though broad in

context, has not been sufficiently developed to identify the functional interdependencies of many of these factors. At this stage in its development, the

model is helpful in identifying key elements or factors and developing an understanding of the specific elements associated with detection and

suppression. Future efforts will extend the model to sufficient detail to

permit formulation of analytical expressions for evaluation of the functional

interdependencies. This will lead to the ability to predict performance for

specific conditions of hazard development, occupant behavior and fire safety

strategy.

The model in figure 24 is consistent with the expression proposed by

Cooper (see section 3) for time required for escape/rescue. Within the context of this framework, Cooper's expression can be recast as follows: Life

safety can be assured in a residential fire if

Tms(TV - T ) - T >0

H V E,R -

where

Tms = margin of safety (time)

Tjj = time to hazard

Tp = time to detection

Tg r

= time to escape/rescue

This expression simply states that the time available (TR

- T^) must be

greater than or at least equal to the time required (T

e r

) for occupant escape

or rescue; that is, T

mg 0. If the occupant must be protected in place, then

32
hazardous levels must not be reached. Figure 25 provides a graphical

illustration of the hazard development and occupant escape/rescue processes

which relate to the above expression. The objective T

mg > 0 can be met by

application of a number of strategies, including early warning detection

(reduce Tp) , control of hazard development (increase TR

) or by adjusting the

needs of the occupants (T

r R

) . The adequacy of each of these strategies,

alone or in some combination, for specific conditions must be determined.

Each of the parameters in the above expression involves the interaction

of elements along major paths in the model (figure 26). The model identifies

the logical relationships of the elements. However, analytical expressions

for the various functional elements and their interdependencies remain to be

developed.

Ongoing research at NBS is directed at doing this. It involves both

theoretical and experimental research to examine the appropriate elements in

the model leading to an ability to predict whether or not the

objective (T

mg > 0) has been met for specific cases. Attention is being given

to developing methods of predicting the performance of smoke detectors and

residential sprinklers within this context.

Current knowledge of the processes involved in detection and sprinkler

suppression is limited, but important progress has been made in recent

years. Work by Alpert [44] and Heskestad [61] provide a basis for predicting

thermal response of sprinklers exposed to heated ceiling jets for unconfined

ceilings typical of large, open rooms such as warehouses. Recent work by

Evans [47] has extended this work to small compartments where limited experimental results indicate that the ceiling jet may be directly influenced by the

formation of a high temperature zone in the upper part of the room early in a fire. While this extension appears promising, further study and validation is

necessary to provide a generalized form of calculation compatible with stateof-the-art analytical fire growth models.

Generalized quantitative expressions for extinguishing agent effects on residential compartment fires are not available. Fire extinguishment involves

a very complicated interaction of physical and chemical processes, including

33
agent particle size formation, particle transport to combustion surfaces, and

the effects of the delivered agent on burning rate, combustion gas generation,

and environmental conditions within the space. Early work by Rashbash [62]

and Magee and Reitz [63] provided limited empirical correlations for water

spray effects on burning fuels. These studies demonstrated that extinguishing

agent effects on burning rate were influenced by individual droplet size as well as the quantity of agent, and the burning characteristics, geometric

arrangement and ventilation conditions associated with the fuel.

Ongoing work by Milke [64] at NBS is directed at extending these efforts

to identify extinguishment thresholds in terms of mean droplet diameter and

Q

quantity for water sprays. Additional ongoing work by Prahl on development

of scaling laws for application in developing experimental correlations for

water droplet formation and initial trajectory, and Alpert [65] on the interaction of fire plumes and water sprays, will aid progress toward analytical

methods for evaluating sprinkler effectiveness for residential rooms.

Finally, there are no current methods that enable one to determine the

effects of other fire safety design features on sprinkler effectiveness.

Historically many designers have assumed that the effect of multiple design

elements is at least additive if not synergistic, but recent experimental work

suggests that this may not always be true. For example, in tests conducted by

the Illinois Institute of Technology Research Institute (IITRI) in 1978 [66]

it was demonstrated that smoke operated automatic door closers in conjunction

with automatic sprinklers provided excellent protection in areas outside the

fire room. However, by closing the door to the fire room, hazardous conditions were reached much sooner in the room of fire origin, often before the

sprinkler responded.

Ongoing and future research at NBS is intended to provide generalized

expressions for detector and sprinkler activation and water spray effects on compartment fires, and result in engineering methods for detection and sprinkler design effectiveness. These efforts should reduce the gaps and liraitaQ

Dr. Joseph Prahl (Case Western Reserve University) has recently initiated a study to develop scaling laws for water droplet formation and initial

trajectory. This work is being performed under a grant from NBS/CFR.

34
tions inherent in the qualitative approach presented in this study, and

identify areas for improvement in detection and suppression technologies.

7. SUMMARY AND CONCLUSIONS

The largest number of annual fire fatalities in the United States occurs

in residential occupancies. Smoke detectors and sprinklers can have a large

impact in reducing residential fatalities. These devices can be used in

retrofit and new construction. As already indicated by various studies,

nationwide use of smoke detectors, installed in accordance with the location

and audibility requirements in the NFPA Standard for Installation of Household

Fire Warning Equipment (NFPA 74), alone could reduce the residential fire

fatality rate by nearly 50 percent. An even larger potential impact would

Q

result from the combined use of smoke detectors and sprinklers . Assuming

reliability of the devices and applicability of limited full scale test

results, combined use of smoke detectors and residential sprinklers could

reduce fatalities on the order of 73 percent for one and two family dwellings,

mobile homes, and apartments. Standard sprinklers in combination with smoke

detectors could provide a 57 percent reduction for the scenarios examined.

Similar benefits appear possible for larger residential occupancies such as dormitories, institutions, hotels and motels.

Approximately 20 to 30 percent of the fatalities in residential

occupancies appear unsavable by current smoke detector or sprinkler technology. These fatalities occur primarily due to intimate exposure of the

individual to the fire, or exposure to a very rapidly developing shielded

fire. In both cases, hazardous conditions frequently occur prior to smoke

detector or sprinkler activation.

The predicted reduction in fatalities is based on certain assumptions

since the costs and practicability of these devices have not been assessed;

full assessments have not been made of the limitations of these technologies,

^The 1980 edition of NFPA 13D, Standard for the Installation of Sprinkler

Systems in One and Two-Family Dwellings and Mobile Homes anticipates the

installation of smoke detectors in accordance with NFPA 74 in addition to a residential sprinkler system.

35
nor have chelr performance, system adequacy and reliability been evaluated;

failure thresholds for significant variations In environmental conditions such

as supply water pressure, maximum furnishing fuel load, etc. have not been

determined; and available experimental data can not be generalized to all

residential occupancies or fire scenarios.

These limitations stem from inadequate knowledge of the physical

processes involved. Therefore NBS has initiated research to provide an understanding of these processes, and to develop analytical techniques for quantitative predictions.

An initial model has been developed which identifies key factors in

providing residential life safety. A simple mathematical expression has been

adapted as a success criterion, and research is ongoing at NBS to address

specific parameters in the expression. Future efforts will be directed at

extending the model to sufficient detail to provide the basis for examining

the functional interdependencies among key factors. Initially, the focus of

this work is on modeling detection and extinguishment of residential fires.

Benefit/cost analyses are being performed at NBS to assess the relative

effectiveness of state-of-the-art detector or sprinkler technologies in

residential occupancies. While performance of these devices is important in

meeting the success criterion, the cost to implement these strategies also is

relevant.

Analytically based models and benefit/cost analysis techniques will

provide a means for development, design, selection and performance evaluation

of fire safety strategies for residential life safety, including the use of

automatic detection and suppression. Specific cases can then be evaluated to

determine the optimum design strategy (e.g., automatic detection, or automatic

detection with corapartmentation) on the basis of (1) hazard development, (2)

occupant conditions, (3) fire safety performance, and (4) economic impact.

36
8 . ACKNOWLEDGMENTS

Special appreciation is extended to the following individuals for

assisting in the review of this paper and providing valuable comments:

Dr. H. Adams, Technical Director, Man-Made Fiber Producers Association,

Inc.

Mr. Irwin A. Benjamin, Benj amin-Clarke Associates, private engineering

consultant

Mr. Arthur E. Cote, Assistant Vice President of Engineering and Technical

Services, National Fire Protection Association.

Mr. Russell P. Fleming, Vice President of Engineering, National Fire

Sprinkler Association.

Mr. E. T. Kubu, Manager of Government-Industry Liaison, Allied

Corporation.

Mr. Tony Shaw, Chairman, Man-Made Fiber Producers Association Technical

Committee and Manager of Technical Information, Hoechst Fibers Industries.

In addition, the author would like to thank Mr. Harold E. Nelson of the

Center for Fire Research and Allan I. Gomberg of Firepro, Inc. (formerly with

the Center for Fire Research) for their guidance and recommendations in

structuring the analysis and providing fire fatality incident data.

9 . REFERENCES

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[3] Uniform Coding for Fire Protection, 1976, NFPA No. 901, National Fire

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37
[4] Fire Protection Handbook, 15th Ed., National Fire Protection

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[5] Custer, Richard L.P. and Bright, Richard G., Fire Detection: The Stateof-the-Art, National Bureau of Standards (U.S.), NBS TN 839, June 1974.

[6] Operation School Burning No. 2, National Fire Protection Association,

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[7] Standard for Installation, Maintenance and Use of Household Fire Warning

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[8] Residential Smoke and Fire Detector Coverage in the United States:

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[9] Hall, John R, et al., Fire Code Inspections and Fire Prevention: What

Methods Lead to Success? , National Fire Protection Assn., Boston, MA,

1979.

[10] Fire in the United States, Fourth Edition, Federal Emergency Management

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[11] Fire Performance Evaluation of the Federal Mobile Home Construction and

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Development, Washington, U.S. Fire Administration, 1980, p. ii.

[12] Schaenman, Philip S. and Herrin, Cheryl L., Evaluation of Mobile Home

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[13] Dana, Gorham, Automatic Sprinkler Protection, 2nd Edition, Wiley, New

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[14] Standard for the Installation of Sprinkler Systems, NFPA 13, 23rd

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[15] Bryan, John L., Automatic Sprinklers and Standpipe Systems, National

Fire Protection Assn., Quincy, MA, 1980.

[16] Yao, Cheng, Application of Sprinkler Technology, presented at Workshop

Engineering Applications of Fire Technology, National Bureau of

Standards, Gaithersburg, MD, April 16-18, 1980, Factory Mutual Research,

Norwood, MA 02062, March 1980.

[17] Bryan, op. cit. pg. 62.

[18] Standard for Installation of Sprinklers in One and Two Family Dwellings

and Mobile Homes, NFPA 13D, First Edition, National Fire Protection

Association, Quincy, MA 02269, 1975.

38
[19] Kung, Hsiang-Cheng , Residential Sprinkler-Protection Study, prepared for

National Bureau of Standards, Factory Mutual Research, (FMRC #22442) , Norwood, MA 02062, November 1975.

[20] Henderson, Norman C., Patton, Richard M., and Larcomb, D. Bruce,

Investigation of Low-Cost Residential Sprinkler Systems, prepared for

National Fire Prevention and Control Admin. (U.S.), Battelle Memorial

Institute, June 1978.

[21] Standard for Installation of Sprinklers in One and Two Family Dwellings

and Mobile Homes, NFPA 13D, 2nd Edition, National Fire Protection Assn.,

Quincy, MA 02269, 1980.

[22] Kung, Hsiang-Chang , et al.. Sprinkler Performance in Residential Fire

Tests, prepared for Federal Emergency Management Agency, U.S. Fire

Administration 79019, Factory Mutual Research, Norwood, MA 02062,

December 1980.

[23] O'Neill, John G., Fast Response Sprinklers in Patient Room Fires, Fire

Technology , Vol. 17, No. 4, November 1981, pp. 254-274.

[24] Report of Congress on Fire Protection Systems: Detectors, Remote Alarm

Systems, and Sprinklers, prepared by Federal Emergency Management

Agency, Washington, D.C. 20472, June 1981.

[25] Federal Fire Experience for Fiscal Year 1963, Washington, Federal Fire

Council, 1964, p. 26.

[26] Thomas, E. P., The Widget in the Ceiling, Navy Lifeline , September/October 1979, p. 12.

[27] Automatic Sprinkler System Performance and Reliability in United States

Department of Energy Facilities 1952-1980, U.S. Department of Energy,

DOE/EP-0052, Washington, D.C. 20545, June 1982.

[28] Marryatt, H. W., Automatic Sprinkler Performance in Australia and New

Zealand: 1886-1968 , Australian Fire Protection Assn., Melbourne,

Australia, 1971.

[29] Fire Protection Handbook, 15th Edition, National Fire Protection Assn.,

Quincy, MA 02269, 1981, pg. 17-3.

[30] McGuire, J. H. and Ruscoe, B. E., The Value of a Fire Detector in the

Home, Fire Study No. 9, National Research Council of Canada, December

1962.

[31] Gomberg, A. and Offensend, Fred L. , A Decision Model for Evaluating

Residential Fire-Risk Reduction Alternatives, National Bureau of

Standards, in preparation.

[32] Stickney, C. Walter, Oregon Life Safety Study of Institutional Care

Facilities, TR 74-3, Society of Fire Protection Engineers, Boston, MA

02110.

39
[33] Stiefel, S. W. and Gomberg, A., Life Saving Potential for Automatic

Sprinkler Systems in Nursing Homes, National Bureau of Standards, NBSIR

in preparation, pg. 11.

[34] 1979-80 NFIRS Data Base, unpublished computer data base.

[35] Cote, A. E. and Moore, D. A., Field Test and Evaluation of Residential

Sprinkler Systems - Los Angeles Test Series, presented to the NFPA 13D

Subcommittee, April 7, 1980, National Fire Protection Assn., Quincy, MA

02269.

[36] Cote, Arthur E., Field Test of a Retrofit Sprinkler System, National

Fire Protection Research Foundation, Washington, D.C. 20024.

[37] Babrauskas, V., Combustion of Mattresses Exposed to Flaming Ignition

Sources, Part 1 - Full Scale Tests and Hazard Analysis, National Bureau

of Standards (U.S.), NBSIR 77-1290, September 1977.

[38] Budnick, Edward K., Mobile Horae Living Room Fire Studies: The Role of

Interior Finish, National Bureau of Standards (U.S.), NBSIR 78-1530,

September 1978.

[39] Kimmerle, G. , Aspects and Methodology for the Evaluation of

Toxicological Parameters during Fire Exposure, J. of Fire and

Flammability/ Combustion Toxicology, Vol. 1, 4-51, February 1974.

[40] Claudy, W. D., Respiratory Hazards of the Fire Service, National Fire

Protection Assn., Quincy, MA 02269.

[41] Stewart, R. D., et al., Experimental Human Exposure to High

Concentrations of Carbon Monoxide, Arch. Environ. Health, Vol. 26, 1-7,

January 1973.

[42] Jin, T. , Visibility through Fire Smoke, Part 2, Report of the Fire

Research Institute of Japan, No. 33, 31-48 (1971). Part 5, Report of

Fire Research Institute of Japan, No. 42, 12-18 (1975).

[43] Gomberg, Alan, Buchbinder, Benjamin and Offensend, Fred J., Evaluating

Alternative Strategies for Reducing Residential Fire Loss - The Fire

Loss Model, National Bureau of Standards, NBSIR 82-2551, August 1982.

[44] Alpert, R. L. , Calculation of Response Time of Ceiling-Mounted Fire

Detectors, Fire Technology , August 1972.

[45] Heskestad, G. , Investigation of a New Sprinkler Sensitivity Approval

Test: The Plunge Test, Technical Report, FMRC 22485, Factory Mutual

Research Corp., Norwood, MA, December 1976.

[46] Heskestad, G. and Delichatsios, M. A., Environments of Fire Detectors

Phase I: Effect of Fire Size, Ceiling Height and Material, NBS-GCR-77-

95, National Bureau of Standards (U.S.), prepared by Factory Mutual

Research, July 1977.

40
[47] Evans, David D. , Plume Flow in a Two-Layer Environment, presented at

21st National Heat Transfer Conference, Seattle, WA, July 24-28, 1983.

[48] Cooper, Leonard Y., A Mathematical Model for Estimating Available Safe

Egress Time in Fires, Fire and Materials, Vol. 6, Nos. 3 and 4,

September/December 1982, pp. 135-144.

[49] Budnick, Edward and Klein, David, Mobile Home Studies: Summary and

Recommendations, National Bureau of Standards (U.S.), NBSIR 79-1720.

[50] Budnick, Edward, Mobile Home Living Room Fire Studies: The Role of

Interior Finish, National Bureau of Standards (U.S.), NBSIR 78-1530,

September 1978, pg. 2.

[51] Heskestad, G. , The Sprinkler Response Time Index (RTI) , presented at

Technical Conference on Residential Sprinkler Systems, April 28-29,

1981, Factory Mutual Research, Norwood, MA 02062.

[52] Bukowski, Richard W., Investigation of the Effects of Heating and Air

Conditioning on the Performance of Smoke Detectors in Mobile Homes,

National Bureau of Standards (U.S.), NBSIR 79-1915, October 1979.

[53] Bukowski, R. W., Waterman, T. E. and Christian, W. J., Detector

Sensitivity and Siting Requirements for Dwellings, National Bureau of

Standards (U.S.), NBS-GCR-75-51 , 1975.

[54] Kung, Hsiang-Cheng, et al.. Field Evaluation of Residential Prototype

Sprinkler - Los Angeles Fire Test Program, Factory Mutual Research - FMRC J.I. 0E0R3 .RA( 1 ) , Norwood, MA 02062, February 1982.

[55] Cote, Arthur E., Final Report on Field Test and Evaluation of

Residential Sprinkler Systems, National Fire Protection Association,

Quincy, MA 02269, December 1982.

[56] Bukowski, Richard W., Test on the Performance of Automatic Fire

Detectors in Health Care Occupancies: A Preliminary Report, National

Bureau of Standards (U.S.), NBSIR 79-1739, April 1979.

[57] O'Neill, John G., Hayes, Warren D. and Zile, R. H. , Full-Scale Fire

Tests with Automatic Sprinklers in a Patient Room: Phase II, National

Bureau of Standards (U.S.), NBSIR 80-2097, July 1980.

[58] Cote, Arthur E., Final Report on Field Test of a Retrofit Sprinkler

System, National Fire Protection Research Foundation, Washington, D.C.

20024, February 1983.

[59] Quintiere, J. G. , Steckler, K. D. and McCaffrey, B. J., A Model to

Predict the Conditions in a Room Subject to Crib Fires, First

Specialists Meeting (International) of the Combustion Institute,

University of Bordeau, France, July 20-25, 1981, Proceedings, The

Combustion Institute, 1981.

[60] Tanaka, T. , A Model of Multiroom Fire Spread, National Bureau of

Standards (U.S.), NBSIR 83-2718.

41
[ 61 ] Heskestad, G. , Physical Modeling of Fire, Journal of Fire and

Flammability, Vol. 6, pp. 253-273, July 1975.

[62] Rashbash, D. J., The Extinction of Fires by Water Sprays, Fire Research

Abstracts and Reviews , 4, 28, 1962.

[63] Magee, R. S. and Reitz, R. D., Extinguishment of Radiation Augmented

Plastics Fires by Water Sprays, 15th International Symposium on Combustion, Combustion Institute, p. 337, 1975.

[64] Milke, J. A., Preliminary Investigation of the Thermophysical Effects of

Water Sprays on Burning Solids, National Bureau of Standards (U.S.), in

preparation.

[65] Alpert, R. , Calculated Interaction of Sprays with Large-Scale, Buoyant

Flows, presented at ASME Winter Annual Meeting, Phoenix, Arizona,

November 14-19, 1982.

[66] Mniszewski, K. and Waterman, T. E., Effects of Open Doors on Sprinkler

Effectiveness in a Patient Room, Final Report No. J8299-1, Illinois

Institute of Technology Research Institute, June 1978.

42
FIRES

DOLLAR

LOSS

CO

CDOc<1) •o

CO0

cc

CO c ~ o

*"*

CO i_

O 0 3aO « g E « O +-» L. Z CO H 0

+-» o

060

CO

+-» =J o 0 O iz

d 3

CC ZCO IO

I-z

LUO

CC

LU

Q.

CvJ

os

<U

tn

03o

a)

v-i •H

rH

00

On

U-to A 3

Source:

NFIRS,

and

NFPA,

NCHS
DOLLAR

FIRES

DEATHS

INJURIES

LOSS

O

CMO

£ C/5 3

CO

CO

O) 2 •- C .3

0

0

I

c

o

o

O

O

c

0

o

c

O)

c

COo

o

E

CO LU

O

0

0

O

c

0

C

0

a I

Q. JZ

< o

• Q. 0 0

'5

CT 0

E

0

E

0 c

LU

k_

3

CO 0

v_ ll Ll

l_

£

o

0 o 3

c 0 c

a «-> 0 JZ JjC *— X 0 Q. c

o LU z o O 3

44

Figure

2.

Causes

of

1981

Residential

Fires

[2]
%

HOUSEHOLDS

WITH

DETECTORS

Figure 3. Growth of Smoke Detector Usage in Single Family

Dwellings [8]

45
Figure 4. Typical Standard Sprinkler Head and Residential

Sprinkler Head Demonstrating Significant Reduction

in Thermal Link Mass for Residential Sprinkler Technology

46
FIRE

GROWTH

RATE

0.4

E

Q

0.3 o

>

1-

0.2 coz

LU

Q

0.1

LLI *

o

2

CO

Figure 5. Eye Level Temperature and Smoke Density in Room

of Fire Origin where Residential Sprinkler

Controlled the Fire [54]

Figure 6. Illustration of Characteristic Residential

Compartment Fires

47
g

DCo

LU

DC

LUa.

>-

LU

DC

48

Figure

7.

Parametric

Model -

Residential

Life

Safety

Scenarios
TIME

Figure 8. Comparison of Activation Times for Smoke Detector (A)

and Sprinkler (B) for Typical Compartment Fire

INCREASING TIME

Figure 9. Graphical Illustration of Escape Time (AT) provided

by Smoke Detector Alarm

49
INCREASING

HAZARD

time

INCREASING TIME

Figure 10. Graphical Illustration of Potential Impact of

Sprinklers in Preventing Hazardous Conditions
<D

o

Cmb

k.a

0

C• Mi

2

o

O

O

H-

+-> o

V-O

<0 k.a 0 0

> 0 <D

-4-> o 0 0 0

k. O

E 0 0

MB

4-» *o JQ

H D 0 c u.

4-» 0

c 0 D 0

"O

0

T3

a

k_ E

o 4-« MB c 0 O 0 0 0 N io

0 E 0 0 +* 0

_> CO I OC CO I

o

<

O < •

If)

Q

0C

<

N

<

I

1 _L 1 o o o o

o o o o

00 CO CM

Oo) 3dniva3di^3i

51

Figure

11.

Ceiling

Gas

Temperature

and

Activation

Times:

Test

10
00 CO

^

CM

a

tr<

N

<

I

C• mmm E

LU

2

H

Oo) 3anivd3d^3i

52

Figure

12.

Ceiling

Gas

Temperature

and

Activation

Times:

Test

11
400|

1

1

1

1

,1

000

-i

4.0 inoo

(W/QO) A1ISN3G "IVOIldO

o

00 T

in

CVJ o• m• CVJ 1- O ^

1- o

T T T

(wdd) NOI1VU1N3DNOO 00

o o o o

o o o o

oo CO CVJ

(Oo) 3aniVd3dl^31

53

Figure

13.

Measured

Conditions

for

Flaming

Upholstered

Chair

[52]
400i

1

1

1

1

1

1

1

1000

-i

4.0

(w/ao) A1ISN3Q nvoildo

IA O U) O io O X) C0C0CMCNJ • • • • I . J

t- OO "I 1 1 1 1 1 1

1 (iudd) NOI1VU1N30NOO 00

o o o o

o o o o

oo (0 CVJ

Oo) 3an±vu3dW3i

54

Figure

14.

Measured

Conditions

for

Smoldering

Upholstered

Chair

[52]
SUCCESS

FREQUENCY

(%)

LEAD TIME (min)

-5 0 10 20

Smoke detector sensitivity - 1%/ft

AT=2 minutes (minimum escape time)

Figure 15. Escape Time for Smoke Detectors Installed

on Every Level [53]

55
SUCCESS

FREQUENCY

(%)

LEAD TIME (min)

-5 0 10 20

Heat detector rating - 135°F

AT = 2 minutes (minimum escape time)

Figure 16. Escape Time for Fixed Temperature Heat Detectors

Installed in Room of Origin [53]

56
GAS

TEMPERATURE

(°F)

TIME (min)

Figure 17. Ceiling Gas Temperatures in Bedroom Adjacent to

Closet for Sprinklered and Unsprinklered Flaming

Closet Fires [54]

57

GAS

TEMPERATURE

(°C)
200

LU

2

(do) aanivaadwai svo

58

Figure

18.

Upper

Room

Gas

Temperatures

and

Sprinkler

Activation

Times

for

Smoldering

Bedroom

Fires

[54]
FIRE

ROOM

ADJACENT

CORRIDOR

MINUTES

MINUTES

59

Figure

19.

Estimated

Escape

Time

from

Patient

Room

and

Along

Corridor

Provided

by

Different

Detector

Types

and

Locations

for

Flaming

Mattress

Fires
300

c

E

UJ

2

I-

(Oo) 3dfUVd3dlAI31

60

Figure

20.

Comparison

of

Ceiling

Gas

Temperatures

and

Sprinkler

Activation

Times

for

Flaming

Mattress

Tests

[57]
ELEVATION

(in)

• Burn room ceiling gas temperature

A Doorway smoke obscuration 0.25 OD/m

Corridor smoke obscuration 0.25 OD/m

TIME (s)

Figure 21. Effect of Different Sprinkler Activation Times on Smoke Filling in

Doorway and in Corridor [57]

61

CEILING

GAS

TEMPERATURE

(°C)
h- m co

co

co

(Do) 3UniVa3dW31 SV9 9NHI30

62

Figure

22.

Illustration

of

Similar

Times

to

Activation

for

Residential

and

Standard

Sprinklers

under

Severe

Early

Fire

Growth

from

Shielded

Combustible

Wardrobe

Fires

[57]
SCENARIO

GROUP

No.

CD Q) <

CLDOOo

COD

h-<

HCO

D < O O O O O -* g

QCo

LU

QC

LU

Q_

LU

QC

LL

Figure

23.

Parameter

Combinations

for

Scenario

Group

#1
PREVENTION

OF

SAFEGUARDING

OCCUPANTS

INCIPIENT

FIRE

FROM

RESULTING

HAZARD 01 T3O

j-J OJ iu

cfl CO

01 •HUc

OJ -a•H

03

OJ fa

"O’ CM

OJu3

60

•H

fa

64
Hazard

threshold

QdVZVH DNISVaaONI 0

E

4-* c

2 I

CGa

CC <D 3

N > O

cG m o

X -D O

0

0

C

o

a

0)

0

65

Figure

25.

Life

Safety

Objective

for

Residential

Occupancies:
PREVENTION

OF

SAFEGUARDING

OCCUPANTS

INCIPIENT

FIRE

FROM

RESULTING

HAZARD

Ps 0)

4-1

X

0) o

4-1

X

CO m >,

4-1 (U 0)

4-i 4-1 •H CO hJ in

>-i <D O 4-1 IM •H

hJ XI

01 iH1

03 c0 o •H

o. 4-1 o c

1-4 05 Ph X•H C 03 o 0) •H Pi

03

03

O

03 4-1 U

D.

N

X o W A 1 cH Pi• (0 w e H H

<u 1 H

/"s

4-1

a

Oa i •H

rC

X

03

H

Co

•H II 4-1 CO in

I—1 X

a)H

pi

vO

CM

a>

>-i 3

60

•H

pH

66
Table 1. Deaths Per Fire:

Family Dwellings

One and Two

Deaths Per No . of Percent of No. of Percent of

Fire Fires Total (%) Deaths Total (%)

1 557 81 557 64

2 86 13 172 20

3 25 4 75 9

4 16 2 64 7

10 1 _ _ 685 100 868 100

Source: 1981 NFIRS Data Base [2 ]

67
Table

2.

Peak

Levels

of

Selected

Hazard

Measurements

at

Eye

Level

Elevation

[54]

68
Table 3.

Peak

Levels

of

Selected

Hazard

Measurements

at

Eye

Level

Elevation

[54 ] l 69

Instrument

Limit
Table 4a. Occupant Conditions where Detectors or Sprinklers

Provide Protection - Smoldering/Flaming Scenarios

Occupant

Status

Occupant Location

Intimate

In

Room

Outside

Room

Asleep/Mobile ? Smoke Detector

Residential Spkr (L)

Smoke Detector

Residential Spkr.

Standard Spkr.

Awake/Mobile ? P

Smoke Detector

Residential Spkr.

Standard Spkr.

Immobile ? Residential Spkr (L) Residential Spkr.

Standard Spkr.

? Indicates Unimown

L Indicates Limited Protection

P Indicates Occupant Action

preempts protection

70
Table 4b. Occupant Conditions where Detectors or Sprinklers

Provide Protection - Flaming Scenarios

Occupant Location

Occupant

Status Intimate

In

Room

Outside

Room

Asleep/Mobile ? Smoke Detector

Residential Spkr.

Smoke Detector

Residential Spkr.

Standard Spkr.

Awake/Mobile ? P

Smoke Detector

Residential Spkr.

Standard Spkr.

Immobile ? Residential Spkr. Residential Spkr.

Standard Spkr.

? Indicates Unknown

P Indicates Occupant Action

Preempts Protection

71
Table 4c. Occupant Conditions where Detectors or Sprinklers

Provide Protection - Shielded Fast Flaming Scenarios

Occupant Location

Occupant In Outside

Status Intimate Room Room

Asleep /Mobile

NP NP

Smoke Detector (L)

Residential Spkr (L)

Standard Spkr (L)

Awake/Mobile

NP NP

Smoke Detector (L)

Residential Spkr (L)

Standard Spkr (L)

Immobile NP NP NP

NP Indicates None Provide Protection

L Indicates Limited Protection

72
Table

5.

Estimated

Protection

Provided

by

Detectors

and

Sprinklers

Major

Interior

Fire

Scenario

Groups

in

Residential

Occupa w

p a; o *h X od

rH

cO 1 •H •rln p CO d 02 XI

02 X) Pd 02 X p p

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02 XI o g xl

0)

d

xp

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d rH

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73
N8S»nu at >

,

j.»; u,». ern o» comm, BIBLIOGRAPHIC DATA

SHEET (See Instructions/

1. PUBLICATION OR

REPORT NO. NBSIR 84-2819

2. Performing O'gen, Report No,

752.08

1. Publication Data

January 30, 1984

4. TITLE AND SUBTITLE

ESTIMATING EFFECTIVENESS OF STATE-OF-THE-ART DETECTORS AND

AUTOMATIC SPRINKLERS ON LIFE SAFETY IN RESIDENTIAL OCCUPANCIES

5. AUTHORiS)

Edward K. Budnick

6. PERFORMING ORGANIZATION (If joint or other t hon NBS, see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

I. Type of Raport & Period Covered

Final Report

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street, City, State, ZIP)

10.

SUPPLEMENTARY NOTES

Document describes a computer program; SF - 185, FlPS Software Summary, Is attached.

11.

ABSTRACT (A 200-word or less factual summary of most significant information. If document Includes a significant

bi bltography or literature survey, mention It here)

The report provides a qualitative assessment of the life safety impact of early

warning fire detection and automatic sprinkler technology in residential occupancies.

This assessment is based on the results of full scale studies and statistics on residential fire fatalities from the NFIRS data base.

Estimates of the impact of three alternatives, smoke detectors, standard automatic

sprinklers, and residential sprinklers, are provided for major fire hazard scenarios

in residential occupancies. The results of this study indicate that significant life

safety benefits can be derived from broad application of detectors and sprinklers in

all residential buildings. Further work is necessary to reduce the gaps which exist

in our understanding of the performance limits, cost-effectiveness, and reliability

of these devices. In addition, there are residential scenarios, for example,

occupants intimately exposed to a fire, where the impact of these devices appears

marginal

.

A quantitative approach is outlined that can lead to a more accurate assessment of the

impact of detectors and sprinklers. An initial framework is presented which identifies the key parameters for residential life safety. A mathematical expression is

proposed as a success criterion. Work is underway to extend the framework to sufficient detail to permit formulation of appropriate analytical expressions necessary

for quantitative evaluation of specific parameters and their interrelationships.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Fire losses; life safety; residential buildings; residential sprinklers,

smoke detectors; standard sprinklers.

13.

AVAILABILITY

2^fUnl imited

| j For Official Distribution. Do Not Release to NTIS

f~! Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C.

20402.

[~X Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

81

15. Price

USCOMM-DC 6043-P80