The value of a fire detector in the home

(1)

Publisher’s version / Version de l'éditeur:

Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la

première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n’arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca.

Questions? Contact the NRC Publications Archive team at

PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information.

https://publications-cnrc.canada.ca/fra/droits

L’accès à ce site Web et l’utilisation de son contenu sont assujettis aux conditions présentées dans le site

LISEZ CES CONDITIONS ATTENTIVEMENT AVANT D’UTILISER CE SITE WEB.

Internal Report (National Research Council of Canada. Division of Building Research), 1961-09-01

READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.

https://nrc-publications.canada.ca/eng/copyright

NRC Publications Archive Record / Notice des Archives des publications du CNRC :

https://nrc-publications.canada.ca/eng/view/object/?id=c827d4f4-4e04-4234-9296-133c22bab60e https://publications-cnrc.canada.ca/fra/voir/objet/?id=c827d4f4-4e04-4234-9296-133c22bab60e

NRC Publications Archive

Archives des publications du CNRC

For the publisher’s version, please access the DOI link below./ Pour consulter la version de l’éditeur, utilisez le lien DOI ci-dessous.

https://doi.org/10.4224/20337834

Access and use of this website and the material on it are subject to the Terms and Conditions set forth at

The value of a fire detector in the home

(2)

»

NATIONAL RESEARCH COUNCIL CANADA

DIVISION OF BUILDING RESEARCH

THE VALUE OF A FIRE DEl'ECTOR IN THE HOME by

J.

H. ｍ｣ｾｵＱｲ･ and B. E. Ruscoe

Internal Report No. 237 of the

Division of Building Research

OTTAWA September 1961

(3)

PREFACE

Questions raised from time to time about the use of fire detection devices in dwellings have prompted the

study which is now reported. The estimates of

effective-ness which are given have been obtained from the exercise of judgment in each of some 342 cases of fire deaths in unshared separate dwellings in the Province of Ontario for which information has been gathered as part of another

study. Since they have been arrived at after the most

careful and systematic assessment, based on a specialist knowledge of fires and of the characteristics of fire detection deVices, they merit serious consideration.

The senior author is a research officer in the Fire Research Section of the Division.having a special

interest in the development and spread of fire. Mr. Ruscoe,

research technician on the project, carried out much of the work of sorting and preparing the data on the individual cases and assisted with the assessments made.

ottawa

(4)

THE VALUE OF A FIRE DETECTOR IN THE HOME by

J.

H. McGuire and B. E. Ruscoe

ｓｭｾｒｙ

The circumstances in which 342 persons lost their lives in Ontario dwellings as a result of fire have been examined and estimates made of the likelihood that each might have escaped had either an ionization chamber or a simple thermal fire detector been operating at the time.

The over-all result is that the estimated saving

of life would have been

4·1

and 8 per cent for the ionization

chamber and thermal detectors respectively.

Brief reference is also made to the economy of installing a fire detector with a view to reducing property damage.

In the Province of Ontario deaths ｲ･ｾｵｬｴｩｮｧ from

fires in bUildings, or from the ignition of clothing average about 175 per year, or 3.1 per 100,000 head of the population. Of this average total of 175, about 115 of the victims died as a result of a fire in a residential bUilding (excluding

deaths resulting from the ignition of clothing). A reduction

of the life risk associated with residential property would thus greatly reduce the over-all incidence of death by fire. With a view to achieving this object many people have recom-mended a more widespread use of fire-detector alarm systems in residential properties.

The object of the work described in this report was to estimate the effect on the fire death rate of the installa-tion of fire detectors in one class of residential property. The work was made possible by having access to the card index system and files set up during the course of a much more

comprehensive program of work aimed at analyzing the causes

of fire deaths (1, 2,

3, 4, 5).

METHOD

The installation of fire detectors and alarms in residential properties is rare; thus it is not to be expected that the fire death analysis, already referred to, involving

a total of about 1,000 deaths (about 175 a year for 6 years),

would yield any significant information on the merits of such

systems. The approach planned for the present study was to

use an estimate of the effect that a fire detector would have

(5)

2

-included in the card index system previously used, which was

confined to factual information. Nevertheless, the

informa-tion on the cards frequently allowed an estimate to be made, and in the remainder of the cases indicated the precise

location of the file containing further information,

news-paper ｣ｵｴｴｩｮｧｾ etc. The accuracy of the estimate as to the

hypothetical effect of a fire detector at each incident is open to question, since it depended on the judgment of the

authors. It is worth recording however that, in sample

surveys conducted independently, the authors' ratings corresponded remarkably well.

Two types of detectors were considered, one an extremely sensitive, ionization chamber, smoke detector and the other a fixed temperature (150°F) device assumed to have a response typical of a bimetal device with as low as possible

a thermal capacity/surface area ratio for such a type. The

performance characteristics of such a fixed temperature device are well known; a number of experiments were per-formed with the smoke detector to give some experience and familiarity with its behaviour.

A preliminary examination of some of the punched cards indicated that a survey covering all residential

properties would give results that were difficult to present

and probably not accurate. The survey was therefore confined

to the "unshared separate dwelling". This reduced the number

of deaths to be investigated to 342 covering the years

1956-60, or a yearly average of approximately 10. As previously

stated, total fire deaths average about 115 annually of

which 115 are the result of a fire in a residential building (excluding the case of a "clothing fire" in a residential building) •

It was assumed that fixed temperature detectors were much cheaper than the smoke detector and could,therefore,

be used in greater numbers. Fixed temperature detectors were

assumed to have been installed at the head of any staircase and, in each instance, in the area of origin of the fire. Two smoke detectors were assumed to have been used, one at the head of the basement stairs and one at the head of the main staircase in a 2-story dwelling or between the living and sleeping areas in a I-story dwelling.

In every case considered the possibility of saving life was estimated according to one of the following six

ratings: 100, 15, 50, 25,

°

per cent, and unknown. nle use

of ratings between 100 per cent and zero can be justified on the grounds that purely factual information indicates that, under remarkably similar circumstances, one individual will

(6)

3

-which this principle was invoked involved the victim's falling asleep while smoking, the bed, chesterfield,etc. on which he or she was lying then igniting.

Besides the above ratings for each individual death, the following information was recorded:

1. Year (a) 1960

(b) 1959

2. Nature of wall and ceiling linings

(a) Incombustible (b) Combustible (c) Mixed

(d) Unknown

3.

Nature of victim

(a) Average adult

(b) Child under 7 years old,

infirm person, or adult 80 or more years old

(c) Unlmown

4.

Location of origin of fire

(a) Other than basement (b) Basement

(c) Unknown

5.

Circumstances surrounding origin of fire

(a) Person falling asleep while smoking (b) Improper use of flammable liquids (c) Intoxication of victim, or adult

responsible for victim (d) Other

6. Whether responsible adult was sleeping

(a) Asleep (b) Awake (c) Unknown

RESULTS

Table I summarizes the most important results of the analysis.

(7)

4

-TABLE I

SUMMARIZED ANALYSIS

Deaths Per cent to be Per cent to be

saved by smoke saved by thermal

detector detector

Average Adult 181 45 8

Child, Infirm, etc. 145 35 1

Total 326 41 8

Besides the 326 cases mentioned in Table I, a further 16 fell in the category "death due to fire in an unshared dwelling", but they were disregarded because lack of information pre-cluded any estimate as to the possible effect of a fire detector.

For the sake of completeness the more detailed table which was originally prepared is also included (see

Table II). It indicates

1. that the total number of deaths considered is sufficient

to give the results of Table I some meaning.

2. that the value of fire detectors in saving lives, on a

percentage basis, does not depend appreciably on the nature of the internal linings of dwellings.

This does not mean that the saving of life per 1,000

installed fire detectors would be independent of the linings

in dwellings. An evaluation of this feature would require a

knowledge of the ratio of combustible to noncombustible-lined

dwellings in Ontario. It would be true, however, if the

ratio were equal to the life loss ratio. It is popularly

thought that the incidence of fires with accompanying life

loss is greater in combustible-lined dwellings. If this

were true then the saving of life per 1,000 installed fire detectors would be greater for combustible-lined than for

noncombustible-lined dwellings. On the basis of the results

quoted the fractional saving of life compared to cases where no detectors are installed would be very similar.

As stated in the previous section further

infor-mation on each incident was also listed. The most

interesting end result was that, of the 342 deaths investi-gated, 313 were associated with fires not originating in

(8)

TABLE II DETAILED RESULTS

y Internal_Linings Incombustible Combustible Mixed Unknown

e

De Detector Effect. D Detector Effect. _De Detector Effect. De Detector Effect.

a _ea

｡ｾ _{ｾｮｫｮｯｷｮ} _{Smoke Thermal} _{t h Unknown Smoke Thermal} at

Unknown Smoke Thermal at Unknown Smoke Thermal

r _{s (Deaths)} _{h s} _hs

(%) (%) s (Deaths) (%) (%) (Deaths) (%) (%) (Deaths) (%) (%)

Average ₁₆ ₁ ₄₅ ₆ ₁₂ ₀ ₆₂ ₁₄ ₀ ₀ ₀ ₀ ₁₃ ₁ ₆₁ ₁₁ Adult \D '"0'1 _Child, .-l Infirm, etc. 5 0 60 10 9 0 44 3 5 0 50 25 10 2

_I

50 9 Average ₁₄ ₁ ₄₈ ₄ ₇ ₀ 40

I

14 4 1 50 12 10

I

1 52 15 Adult I e-'"0'1 _Child, 16 .-l Infirm, etc. 3 0 80 12 0 55 21 2 0 50 12 4 0 19 6 Average ₁₆ ₀ 47 9 8 0 60 22 1 0 75 0 11 1 41 17 CD Adult '" 0'1 _Child, .-l Infirm,etc. 15 0 31 7 9 0 39 6 2 0 0 0 16 0 32 9 Average ₁₃ ₀ ₄₄ ₁₁ ₁₀ ₀ ₅₂ ₀ ₃ ₀ ₄₄ ₁₆ ₁₂ ₂ ₃₂ ₃ 0'1 Adult '" 0'1 _Child, .-l ₂₅ ₀ ₃₀ ₄ ₁ ₀ ₁₀₀ ₂₅ ₁ ₀ ₂₅ ₀ ₆ ₁ ₃₂ ₀ Infirm, etc. I Average ₂₁ ₁ ₃₀ ₀ ₈ ₀ 19 ' 3 6 0 41 8 7 2 I 50 I 0 0 Adult \D 0'1 _Child, .-l ₅ ₁ ₃₃ ₀ ₁₂ ₀ ₄ ₀ ₃ ₁ ₀ ₀ ₅ ₀ ₃₀ ₀ Infirm, etc. Average ₈₀ ₃ ₄₂ ₆ ₄₅ ₀ ₄₈ ₁₀ ₁₄ ₁ ₄₆ ₁₀ ₅₃ ₇ ₄₇ ₁₀ Adult .-l al _Child,

...

₀ _{Int'irm, etc.} 53 1 36 6 43 0 36 8 13 1 31 12 41 3 34 6 E-i Total 133 4 40 6 88 0 42 9 27 2 39 11 94 10 41 8 Vl

(9)

6

-basements, 11 with fires originating in -basements, and 18 with fires in which the story of origin was unknown.

A number of the incidents in which poor ratings were given to the hypothetical effect of a fire detector were

associated with bad practice. The number of deaths falling in this category was 90 of which 21 resulted from the improper

use of flammable liquids; 48 deaths WRre associated with falling asleep while smoking, and 21 were associated with intoxication. A death was considered to fall in one or other of the latter two categories if the criteria "fell asleep while smoking", or

"intoxicated" applied to the victim personally or to the adult who could otherwise have attempted to save a child, an aged or infirm victim.

A factor of great interest is the extent to which a fire detector will protect a sleeping person. A breakdown of Table I giving information on this question is presented in Table III. The total number of deaths included in Table III is two fewer than in Table I because the available information in these two cases did not include a statement as to whether the victim or the responsible person was asleep.

TABLE III

EFFECT OF SLEEPING

Responsible person asleep Responsible person not asleep De Per cent to Per cent to De Per cent to Per cent to

at be saved by be saved by at be saved by be saved by

h s smoke thermal h smoke thermal

detector detector s detector detector

Average ₁₂₉ 57 12 51 16 1 Adult Child, Infirm, etc. 76 62 13 68 10 1 Total 205 59 12 119 13 1

. The average fire-conscious individual generally

be11eves that his risk of dying as a result of fire is greatest when he is asleep and that a fire detector installation will greatly reduce this particular risk. Some comment is therefore required on the estimated result, given in Table III that even the most sensitive fire detector available will only'reduce the over-all risk to a sleeping individual by a factor slightly above 2 (59 per cent).

(10)

7

-One factor responsible in some small measure for this low rating is that 69 of the 205 deaths involved were associated with the victim's falling asleep while smoking,

or with intoxication. The explanation of the remaining deaths

for which poor ratings were assigned is primarily associated with the behaviour characteristics of human beings and with the fact that most deaths are caused by toxic gases or lack of oxygen, the onset of unconsciousness in these circumstances

being without warning. Death frequently occurs when victims

delay leaving a building or re-enter it for various reasons

such as the rescue of other individuals or valuable property, or

need of warm clothing in subzero weather. Cases also arise

in which the death of a would-be rescuer results from thermal effects; a victim's failure to leave the building is often associated with the rapid development of the fire which cuts

off his escape route.

In more than one case death could be attributed to the difficulty in wakening the victim despite no extraneous influences such as sleeping drugs.

ｾＮ

The difference between the ratings attributed to the smoke and to the thermal detectors (59 ana 12 per cent respectively in the case of sleeping individuals) is purely a function of the modes of operation of the two detectors,

particularly in relation to the fire that develops slowly. Such a fire will usually be detected at a fairly early stage

by an ionization chamber smoke detector. To be detected by

a thermally operated device of the type considered, a tempera-ture of 150°F or more must have developed in the region of the

detector. By the time such a condition has been established,

as in the case of certain slowly developing fires, large quantities of smoke have been generated which could make escape routes untenable or cause death even in areas remote from the fire.

PROPERTY LOSS

The scope of this note is pr-Lmar-tLy concerned with

life loss in "unshared separate dwelli.ngs", but a cursory examination of the economic value of a fire detector in reducing the over-all property loss is so simple and yet so informative that it is worth including.

A convenient approach to this problem would be to consider the annual property loss in Ontario associated with

"unshared separate dwellings". This figure is not available,

but the reports of the Dominion Fire Commissioner indicate that residential property losses in Ontario for the period considered in this note are in the region of $6,000,000.00

per year. A figure which may be taken to approximate the

number of residences covered by the above figure is the

ｬｾＺＧｾ［ＬＮｾＮ re ｾｎｾＮ

ｉ

_ｾＮ

I

---.;

RG"""·__ﾷﾷﾷﾷｾﾷＮＬＮＬ

(11)

ｾｾｾｾ ..｟ｾｾｾｾｾＭＭｾｾＭｾｾＭＭｾＭＭＭＭＭＭＭＭＭＭＭＭＭ｟

....

8

-number of "households" in Ontario, as defined by the Dominion

Bureau of Statistics. Between 1956 and 1960 the number ranged

between 1,390,000 and 1,590,000, so that a figure of 1,500,000

will serve as an approximate average for the purposes con-sidered here.

The average fire loss per dwelling unit, therefore,

is only $4 per annum. If fire detector installations were

assumed to be 100 per cent effective in eliminating property

loss, and if their lifetime were assumed to be 10 years, then

the universal installation in small residences would only prove

economic if the cost per installation were less than $40.00.

The assumption of 100 per cent effectiveness involved in the

above calculation is such a substantial departure from the truth, especially where low-cost thermally operated detectors are considered, that the economic cost of a fire detector

system, from the property loss point of view, should be

considered to be lower than ｾｲＴＰＮ 00 by a factor greater than

2, and possibly as high as 10 or more. It is probable that

the installation of fire detectors in small residential

properties can only be economically justified from the property risk aspect in very specialized cases.

The above calculations relate to a total loss that includes large residential property losses, whereas the con-clusion has been taken to apply to small residential properties. The magnitude of the error in the present context, however, may be neglected.

SCOPE OF RESULTS

It cannot be overemphasized that the scope of this note is confined to "unshared separate dwellings" and small

residences. In such buildings as schools, department stores,

and warehouses, some form of fire detector can prove extremely valuable from either or both life safety and property aspects. REFERENCES

1. ｓｨｯｲｴ･ｾ G. W. and G. Williams-Leir. Fire deaths in the

Province of Ontario 1954. DBR Internal Report

No. 72, September 1955.

2. Williams-Leir, G. Fire deaths in the Province of Ontario

1955. DBR Internal Report No. 86, September 1956.

3.

Williams-Leir, G. Coding manual for analysis of Ontario

fire deaths, 1956. DBR Internal Report No. 100,

September 1956.

ｾｲｾＺ

(12)

9 -4.

Williams-Leir, G. Fire deaths in the Province o£ Ontario 1956 and 1957. DBR Internal Report No. 124, January 1959.

5.

Williams-Leir, G. Fire deaths in the Province of Ontario 1958 and 1959. DBR Internal Report No. 211, December 1960.