NBSIR 75-700

Results of Full-Scale Fire Tests

f With Photoelectric Smoke Detectors

Richard W. Bukowski and Richard G. Bright

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

September 1975

Final

QC

100

.U56

75-700

1975

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
41 "*
NBSIR 75-700

RESULTS OF FULL-SCALE FIRE TESTS

WITH PHOTOELECTRIC SMOKE DETECTORS

Richard W. Bukowski and Richard G. Bright

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D, C. 20234

September 1975

Final

U.S. DEPARTMENT OF COMMERCE, Rogers C.B. Morton, Secretary

James A. Baker, III, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary for Science and Jectinology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director

Contents

Page

LIST OF FIGURES iv

LIST OF TABLES V

1. INTRODUCTION 1

2. EXPERIMENTAL PROCEDURES AND MATERIALS .... 3

2.1. Fire Test Room 3

2.2. Instrumentation 4

2.2.1. Smoke Density Measuring Equipment , 4

2.2.2. Temperature Recording 4

^ " 2.2.3. Carbon Monoxide 4

2.2.4. Detector Actuation 4

2.3. Test Materials 4

2.3.1. Shredded Paper 5

2.3.2. Polystrene .....

5

2.3.3. Gasoline 5

2.3.4. Wood Brand (UL Class A) 5

2.3.5. Cotton 5

2.3.6. Polyurethane 6

2.4. Smoke Detectors 6

2.5. Test Procedures 6

3. RESULTS . . . ; 8

4. DISCUSSION 8

4.1. Test Series No. 1 - Shredded Paper 8

4.2. Test Series No. 2 - Polystyrene 12

4.3. Test Series No. 3 - Gasoline - 100 cc 12

4.4. Test Series No. 4 - Gasoline - 200 cc 12

4.5. Test Series No. 5 - One Wood Brand 13

4.6. Test Series No. 6 - Two Wood Brands 13

4.7. Test Series No. 7 - Two Wood Brands 13

4.8. Test Series No. 8 - One Wood Brand 13

4.9. Test Series No. 9 - Wood Brand on Hot Plate . ,.. . . . . 14

4.10. Test Series No. 10 - Polyurethane - Two Pieces "."1"'.. . 14

4.11. Test Series No. 11 - Polyurethane - Three Pieces .... 14

4.12. Test Series No. 12 - Polyurethane - One Piece 15

4.13. Test Series No. 13 - Smoldering Cotton , , . 15

4.14. Carbon Monoxide 16

4.15. Average Air Velocities 17

4.16. Temperatures 17

4.17. Photoelectric Smoke Detector "J" 18

5. SUMMARY AND CONCLUSIONS 18

6. ACKNOWLEDGEMENTS 22

7. REFERENCES 22

ili
LIST OF FIGURES

Figure 1.

Figure la. Results of fire test No.

orr TO- A'

Figure 2. Results of fire test No. 2

Figure 3. Results of fire test No. •

Figure 4. Results of fire test No. • • • •

Figure 5. Results of fire test No.

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t: B qms J

•

Figure 6. Results of fire test No. •

Figure 7. Results of fire test No.

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Figure 8. Results of fire test No. 8 !;> j-ijf f^ffrtt?? horn-/*

.1 .<

• ,v • • f- •

Figure 9. Results of fire test No.

Figure 10. Results of fire test No.

Figure 11. Results of fire test No.

Figure 12. Results of fire test No.

Figure 13. . Results of fire test No.

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•

Figure 14. Results of fire test No. •.:» f--.T'p

•

Figure 15. Results of fire test ^No. •

Figure 16. Results of fire test No.

W -inC.) — H Figure 17. Results of fire test No.

Figure 18. Results of fire ifest Mr

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Figure 19. Results of fire test No. on"

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Figure 20. Results of fire test No.

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Figure 21. Results of fire test No.

Figure 22. Results of fire test No.

Figure 23. Results of fire test No.

iv
LIST OF FIGURES, cont'd

Page

Figure 24. Results of fire test No. 25 48

Figure 25. Results of fire test No. 26 49

Figure 26. Results of fire test No. 27 50

LIST OF TABLES

Table 1. List of Smoke Detectors 7

Table 2. Description of Test Fires 9

Table 3. Detector Alarm Response - In Seconds 10

Table 4. Detector Alarm Response - In Seconds Arranged by

Test Series 11

V

RESULTS OF FULL-SCALE TESTS WITH PHOTOELECTRIC SMOKE DETECTORS

Richard W. Bukowski''"

and

Richard G. Bright

In February 1974, a series of full-scale fire tests were

conducted to determine whether photoelectric-type smoke detectors could respond to the same types of fires used to assess

the performance of ionization-type smoke detectors. The types

of fires employed in the tests are the same as those outlined

in Underwriters' Laboratories, Inc., Standard No. 167. In

addition to the UL-167 test fires, fires involving polyurethane (flaming mode) and cotton (smoldering mode) were added

to the test series. One detector, utilizing a Taguchi gas sensor (TGS) , was included in the test series for evaluation

purposes. The test results indicated that the better photoelectric smoke detectors, i.e., those having little obstruction

to slow-moving smoke can, in general, detect the same test

fires as the ionization chamber smoke detectors in approximately the same time scale. For the smoldering cotton fire,

the photoelectric detectors were significantly faster than the

ionization chamber detectors. The TGS fire detector was unable

to detect most of the test fires but the standard fires are not

that standard or specific and hence present a significant am- biguity.

Key words: Fire detectors; ionization chamber smoke detectors;

photoelectric smoke detectors; smoke detectors; Taguchi gas sensors.

1-. INTRODUCTION

There are two different types of conventional smoke detectors sold

in the U.S. The difference between the detectors is in the method used

to sense the presence of smoke. The one smoke detector, generally

referred to as a photoelectric detector, light scattered from smoke particles that have entered the sensing chamber of the detector is used to

actuate an alarm. In the other smoke detector, generally referred to as an ionization chamber detector, a radioactive source material ionizes the

air within the sensing chamber, producing a minute current flow. When

smoke particles enter this sensing chamber, the particles cause a reduction in this current flow which is used to actuate an alarm. For a more

detailed description of conventional smoke detectors as well as other

fire detectors see [1]^.

the time this paper was written the author was a Research Associate

for Underwriters' Laboratories at the National Bureau of Standards.

Mr. Bukowski has returned to UL.

lumbers in brackets correspond with the literature references listed at

the end of this paper.

1
The major testing and approvals laboratory for smoke detectors in the

U.S. is the Underwriters' Laboratories (UL) of Northbrook, Illinois. At

present, UL is testing conventional smoke detectors to two different

standards. Photoelectric smoke detectors are tested to the requirements

of UL-168 [2] while ionization chamber smoke detectors are tested to

UL-167 [3]. In addition, if nonconventional smoke detectors, i.e., detectors using combustion aerosol sensors other than photoelectric or ionization chamber sensors, are submitted to UL for examination, these non- conventional smoke detectors are subjected to the requirements of UL-167

as opposed to UL-168.

These two standards are almost identical except for one significant

difference. This difference is the requirement in UL-167 that the smoke

detector perform satisfactorily in sensing four, full-scale fire tests.

UL-168 omits the full-scale fire tests, a requirement that makes UL-167

the more demanding of the two standards. UL-167 requires that at least

two of four detectors subjected to each of four standard fires shall alarm

within two minutes for the shredded paper, the polystyrene and the gasoline

test fires. Alarm within four minutes is required for the wood brand test

fires.

This difference between the two standards has been the subject of some controversy. The controversy becomes particularly strident when the developer of a new combustion aerosol sensor approaches UL for an exainination

of his detector and discovers his detector must pass the requirements of

UL-167 as opposed to UL-168.

It has been argued that there should be only one standard for testing

and approval of smoke detectors regardless of the sensing method used. It

is difficult to quarrel with this thesis, particularly if one considers

that the smoke detectors' end use is the same; that is, the detection of

fires. As UL-167 is the more rigorous of the two standards, primarily

because of the inclusion of full-scale test fires, UL-167 is considered

to be the most appropriate to use as a. basis for a single standard.

Photoelectric smpke detectors have, however, been tested and approved

under UL Standard 168 for several years. The question that arises is how

well would the photoelectric smoke detectors perform if subjected to the same full-scale fire tests as are the ionization chamber smoke detectors?

It was an attempt to answer this question which stimulated the series

of tests reported herein. NBS, in cooperation with UL, conducted a series of 26 fire tests at the UL facilities in Northbrook, Illinois,

during the period of February 11-15, 1974. The same test facilities and

the same test fires as described in UL-167 were utilized. In addition to

the four standard test fires of UL-167, a smoldering cotton fire and

several flaming polyurethane flexible foam fires were added to the test

series. The purpose in adding the smoldering cotton fire to the test

series was to compare the performance of photoelectric detectors against

ionization chamber detectors to a non-flaming cellulosic fire. Polyurethane is used as a fire test material in Europe for assessing the performance of smoke detectors.

2
Eight different photoelectric smoke detectors were chosen for the

test series. Seven of these detectors were chosen because of their good

response to slow-moving smoke as determined by laboratory analysis at NBS.

It was thought this would be the key as to whether or not these photoelectric smoke detectors would perform satisfactorily. The eighth photoelectric smoke detector chosen was one noted for having response problems to

slow-moving smoke. Laboratory experience indicated that this detector

would experience difficulty in detecting the test fires. To give the

detector every chance its sensitivity was set as high as possible without

provoking false alarms.

For correlation and comparison purposes, two ionization chamber

smoke detectors were included in the test series. One was a singlestation model of the type sold for residential protection. The other was

a unit-type or commercial detector used in automatic fire detection

systems of the type installed in warehouses, nursing homes, and computer

spaces.

Several U.S. detector manufacturers are selling smoke/fire detectors,

using the Taguchi gas sensor (TGS). The TGS sensor is manufactured by

Figaro Engineering of Osaka, Japan.

The TGS sensor is a sintered N-type semiconductor bulk device mainly

composed of tin dioxide (Sn02) whose conductivity increases in the presence

of combustible gases such as carbon monoxide, methane, propane and, to a lesser extent, the unburnt hydrocarbons present in some fires. When used

with a simple amplifier, carbon monoxide on the order of 300 to 1,000

parts per million can be detected. In addition, if several combustible

gases are present in the atmosphere, such as carbon monoxide and unburnt

hydrocarbons, the TGS sensor will respond to the cumulative effect of

these gases. For additional information on TGS sensors as smoke and fire

detectors see reference [4]. One detector, employing the TGS and sold as

a single-station, home smoke/fire detector, was added to the test series

for evaluation purposes. The particular detector chosen is equipped with

a meter which gives an analog indication of the detectors 's shift towards

alarm threshold. The detector also includes an alarm horn within the

detector enclosure which sounds an alarm when the appropriate threshold is

reached. .

2. EXPERIMENTAL PROCEDURES AND MATERIALS

2.1. Fire Test Room

The fire test series was conducted in UL's east fire test room. This room is a large open space 18 m by 18 m (60 ft by 60 ft) by 5 m

(15.75 ft) high. The test fires were positioned 1.2 m (3.75 ft) off the

floor or about 3.7 m (12 ft) below the ceiling. The smoke detectors were

placed on the ceiling approximately 6.4 m (21 ft) from the point directly

over the fire center, which corresponds approximately to a 9-meter (30-ft)

spacing pattern for the detectors. (See fig. 1 for test room layout.)

3
2.2. Instrumentation

The following measuring and recording equipment was employed during

the test series.

2.2.1. Smoke Density Measuring Equipment

Two photometric units were used to measure the visible smoke

obscuration/optical density. These were fastened to the ceiling. One

was placed about 1.5 metres (five feet) from and parallel to a line

joining the fire center and the detectors and the other was placed just

in front of the detectors (see fig. 1) . Each photometric unit consisted

of a barrier-layer-type photoelectric cell spaced 1.5 m (five feet)

from a tungsten filament, automotive-type spotlight energized from a constant voltage source. The output of the photocells was connected to a Honejrwell, two-pen, chart recorder.

2.2.2. Temperature Recording

One thermocouple was placed directly over the fire and one was

placed at the detectors' location. The temperatures were recorded on a Honeywell, multipoint chart recorder.

2.2.3. Carbon Monoxide

Carbon monoxide concentrations in parts per million were continu-,

ously monitored and recorded during all tests. A pickup tube was placed

on the ceiling and positioned just in front of the detectors. This tube was connected to a CO monitor (Ecoloyzer Model 2400) . The output of the

monitor was connected to a strip-chart recorder.

2.2.4. Detector Actuation

The time of detector actuation was recorded on a 25-clock annunciator panel which indicated detector operation to the nearest second.

Electrical signals were taken from the single-station smoke detectors'

alarm horn circuitry and these signals were used to stop the respective

detector's clocks. The normally-open relays within the commercial

detectors were used to stop their respective clocks.

2.3. Test Materials

The test fire included six different materials of which the first

four were those specified in UL Standard No. 167. A description of the

test fire materials follow.
2.3.1. Shredded Paper

This test fire consisted of 227 g (1/2 lb) of newsprint torn in

strips approximately 0.95 cm (3/8 in) wide and 15 to 61 cm (6 to 24 in)

long. The paper strips were placed in a cylindrical receptacle 0.64 cm

(1/4 in) mesh hardware cloth. The overall dimensions of the receptacle

were 30 cm (12 in) round by 61 cm (24 in) high with a hardware-cloth

bottom positioned 15 cm (6 in) above the base. The paper was fluffed up

in such a way as to produce a significant volume of smoke before open

flaming took place. Ignition was by a kitchen match applied to the

bottom center of the basket.

2.3.2. Polystyrene

Fifty-seven grams (2 oz) of spagetti-type, foamed, polystyrene

packing material, with no flame inhibitor, was placed in the same wire

basket used for the shredded paper fire tests. The polystyrene was

ignited by 50 cc of ethyl alcohol placed in a pan positioned under the

bottom center of the basket.

2.3.3. Gasoline

Two hundred cubic centimeters (200 cc) of regular, leaded motor

gasoline was placed in a 23-cm (9-in) diameter, steel pan, 3.8 cm (1-1/2

in) deep. Ignition was by common match. The gasoline in the pan was

kept covered, to prevent evaporation, until ignition.

2.3.4 Wood Brand (UL Class A)

The UL Class A wood brand is a wood crib composed of three layers of

kiln-dried, Douglas fir, wood strips. Each strip was 1.9 cm (3/4 in)

square by 30 cm (12 in) long. Twelve strips were used for each layer and

were stapled together. Each layer was placed at right angles to adjacent

layers. Overall dimensions of the wood cribs were 30 x 30 x 6 cm (12 x

12 X 2-1/4 in) high. The crib was ignited by 100 cc of denatured alcohol

consisting of 95% ethanol and 5% methanol. The alcohol was contained in

the same pan as used for the gasoline test fire.

2.3.5. Cotton

Approximately 900 g (2 lbs) of raw cotton was placed in a 30-cm (12-

in) square pan and placed on a 1000-watt, 120 VAC, hot plate.

5
I

2.3.6. Polyurethane

Pieces of flexible polyurethane foam, 30 x 30 x 8 cm (12 x 12 x 3

in) were placed in a pan constructed of aluminum foil. The pan was

shaped to fit snugly around the base of the foam pieces. The sides of

the pan flared out slightly and were about 8 cm (3 in) high. The polyurethane foam was ignited by 10 cc of ethyl alcohol, poured into the pan

along one side of the foam. Ignition of the alcohol was by kitchen

match.

The materials and the quantities used produced fires of similar

burning time and smoke buildup rates with the exception of the smoldering

cotton test. In this test, a considerably longer time was necessary to

develop sufficient smoke at the detector site for detection. Whereas all

the other test fires were essentially complete in about five to six

minutes, the smoldering cotton fire was allowed to run about 40 minutes.

vr' •

' ' 2.4. Smoke Detectors

Eleven detectors were included in the test series. Eight were

photoelectric smoke detectors, two were ionization chamber smoke detectors,

and one was a detector employing a semiconductor gas sensor commonly

known as a Taguchi gas sensor (TGS) . A list of all the detectors used in

the test series along with their pertinent operating characteristics will

be found in table 1.

The ceiling-mount detectors were fastened to 2.5 x 20 cm (1 in x 8

in) wood boards. These boards were then affixed to the ceiling approximately 6.4m (21 ft) horizontally from the point above the center of the

test fires. For the three wall-mount detectors, 2.5 x 20 cm (1 in x 8

in) wood boards, approximately 20 cm (8 in) long, were fastened in a vertical position to the ceiling boards. The detectors were then positioned on the vertical board surfaces in an approximation of a wall-mount

position. The wall-mount detectors were placed so that the ends of the

detectors faced towards the smoke flow from the test fires.

2.5. Test Procedures

The procedure used in nearly all of the test fires was to ignite the

test material and allow the material to be completely consumed while

continuously recording the smoke density at the ceiling on the two smoke

density units and the carbon monoxide levels at the detector locations.

The maximum temperatures over the fire and at the detector locations were

recorded as well as the alarm trip points for the detectors. The velocity

of the smoke along the ceiling was calculated by averaging the time taken

by the smoke front to pass from the first smoke density measuring unit to

the second unit. Each test was terminated when it was apparent the smoke

had dropped below detectable levels. The test room was then ventilated

and all products of combustion removed from the room. All detectors and

test apparatus were then reset for the next test.

6
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3. RESULTS

The results of 26 test fires are reported on herein. The test

fires are numbered sequentially from No. 1 to No. 27. Test No. 18 was

omitted. This test, which was of a fire-retardant- treated polyurethane

foam, was a failure in terms of smoke output as the fire went out

immediately after consumption of the alcohol ignition fuel.

The 26 test fires have been grouped into 13 test series for clarity

purposes; tests of identical materials under the same conditions have

been listed under one test series number. Table 2 gives the regrouping

of the test fires into the test series.

Table 3 presents the alarm response times of the various smoke

detectors for each of the test fires. In table 4, the detector alarm

response times have been regrouped by test series to follow table 2's

format

Figures la through 26 present the following pertinent data for each

test fire: detector alarm response times; smoke density buildup as measured by the light beam in front of the detectors; type of fire and

ignition source; maximum CO levels at the detector site; average velocity

of the smoke front; and temperatures over the fire and at the detector

site.

Only those smoke detectors that were able to detect most of the

test fires are shown on figures la through 26. Therefore, due to inadequate detection response, detectors "Jf" and "K" were omitted from the

figures.

" 4. DISCUSSION

4.1. Test Series No. 1 - Shredded Paper

. This series included test fire Nos. 1, 2, 3 and 10. The shredded

paper test series was quite difficult to reproduce with consistent

results. While UL-167 is silent on this point, the shredded paper must

be fluffed up in such a way as to burn in a smoldering mode for several

seconds after the match ignition before bursting into flame if any

appreciable smoke is to be produced. If this is not done, then the

paper immediately bursts Into flame and little or no smoke is produced.

This was the case in test No. 2 where the two ionization chambers and

one photoelectric detector were the only detectors to respond.

The procedure UL follows in this test is to fluff the shredded

paper in such a way that smoke is produced for several seconds before

flaming begins. When flaming begins, a hole is punched in the smoke

cloud causing it to resemble a large doughnut. The thermal energy of

the now flaming paper pushes the smoke ring out along the ceiling in an ever increasing diameter until the smoke ring passes the detector location on the ceiling. The pulse of smoke is of sufficient density to

8
Table 2. Description of Test Fires

Test

Series

Test

Numbers Types of Test Fires

#1 1-2-3-10 227 g (8 oz) of shredded paper in hardware cloth basket. Match ignited in bottom

center.

#2 8-9-27 57 g (2 oz) of polystyrene packing

material, ignited by 50 cc of ethyl alcohol.

#3 6 100 cc of motor gasoline, match ignition.

#4 7 200 cc of motor gasoline, match Ignition.

#5 4-5 Class A wood brand ignited by 100 cc of

ethyl alcohol.

#6 11-12 Two Class A wood brands ignited by 100 cc of ethyl alcohol.

#7 13-14-21 Two Class A wood brands ignited by 25 cc of ethyl alcohol.

#8 22-23 One Class A wood brand ignited by 10 cc of

ethyl alcohol.

#9 15 Class A wood brand on 1000-watt hot plate.

Immediate ignition, flaming fire.

#10 16 Two 30 X 30 X 8 cm (12 in X 12 in X 3 in) pieces

of flexible polyurethane foam ignited by 10 cc of ethyl alcohol.

#11 17A-19-24 Three 30 x 30 x 8 cm (12 in x 12 in x 3 in) pieces

of flexible polyurethane foam ignited by 10 cc of alcohol.

#12 25-26 One 30 x 30 x 8 cm (12 in x 12 in x 3 in) piece

of flexible polyurethane foam ignited by 10 cc of

ethyl alcohol.

#13 20 Raw cotton, 907 g (2 lbs), in pan on 1000-watt hot plate.

9
Table 3 Detector Alarm Response - In Seconds

Detectors

Test

No.

Photoelectric B Photoelectric C Photoelectric Photoelectric E

Photoelectric F

.

Photoelectric G Photoelectric H

Ion

Chamber I

1

Ion

Chamber

Photoelectric K

TGS

Semiconductor

1

2 30 46

29

30

45

42

27 29 28 36 34 33

32

30

45

45

30

27

27

38

35

56 36

3

4 28 26 28 27 32 31 —

——

•J 41

62 52 55 72 58 57 107 44 39

7 63 55 76 76 59 64 132 46 NR

8 44 52 42 46 42 44 41 42 31

9 34 30 31 36 30 41 34 32 NR

10 28 28 27 28 28 34 31 30 28

11 49 51 53 58 58 49 52 43

12 48 56 49 55 * 51 46 49 47

13 49 49 54 119* 52 47 70 47 44

14 47 53 88 * 63 49 45 53 46

15 * 139 113

16 156 103 162 * 138 13'4 90 109

17A 154 108 163 * 138 170 85 108 f 19 123 102 124 * 124 119 97 109

20 1,656 1,582 1,754 1,762 1,632 1,690 1,^54 IND

21 74 67 76 103 111 74 74 72 73 160

22 103 '97 103 130 118 102 103 106 110

23 96 92 101 124 102 100 95 102 101

24 138 111 141 134 136 138 92 114

25 134 109 145 134 132 141 104 120

26 127 137 138 131 133 134 118 113

27 51 51 52 55 54 58 50 48

Note: No alarm or indication

IND Indication but no alarm

* Clock timer malfunction

NR Not resettable

10
Table 4. Detector Alarm Response

- In Seconds Arranged by Test Series

Test Series

Test Nos.

A Photoelectric B Photoelectric C Photoelectric D Photoelectric E Photoelectric F Photoelectric G Photoelectric H

Ion

Chamber I

Ion

Chamber J Photoelectric K

TGS

Sensor

Series No. 1 - Eight ounces (250 g) of shredded paper

1

2 30 4629

30

27 29 28 36 34 33

32

30

30

27

27

56 36

3 28 26 28 27 32 31

10 28 28 27 28 28 34 31 30 28

Series No, 2 - Two ounces (57 g) of polystyrene

8 44 52 42 46 42 44 41 42 31

9 34 30 31 36 30 41 34 32 NR

27 51 51 52 55 54 58 50 48

Series No. 3 - 100 cc of motor gasoline

6 62 52 55 72 58 57 107 44 39

Series No. 4 - 200 cc of motor gasoline

7 63 55 76 76 59 64 132 46 NR

Series No. 5 - One wood brand- ignited by 100 cc of alcohol

45 45

42 41

45

45

38

35

Series No. 6 - Two wood brands-ignited by 100 cc of alcohol

11 49 51 53 58 58 49 52 43

12 48 56 49 55 51 j 46 49 47

Series No. Two wood brands-ignited by 25 cc of alcohol

13 49 49 54 119* 52 • 47 70 47 44

14 47 53 88 * 63 49 45 53 46

21 74 67 76 103 111 74 74 72 73 160

Series No. 8 - One wooc brand-ignited by 10 cc of alcohol

22 103 97 103 130 118 102 103 106 110

23 96 92 101 124 102 100 95 102 101

Series No. 9 - One wood brand-on hot plate

15 ___ * 139 113

Series No. 10 - Two pieces of polyurethane foam--ignited by 10 cc of alcohol

16 156 103 162 * 138 134 90 109 ___ ___ Series No. 11 - Three pieces of polyurethane foam-ignited by 10 cc of alcohol

17A 154 108 163 * 138 170 85 108

19 123 102 124 * 124 119 97 109

24 138 111 141 134 136 138 92 114

Series No. 12 - One piece of polyurethane f oam- ignited by 10 cc of alcohol

25 134 109 145 134 132 141 104 120

26 127 137 138 131 133 134 118 i 113

1 Series No. 13 - Two pounds (900 g) of raw cotton on hot plate

20 1656 1582 1754 1762 1632 1690 i 1654 IND

Note: No alarm or indication

IND Indication but no alarm

* Clock timer malfunction

NR Detector not resettable

J.I
operate the better photoelectric smoke detectors. In the test series,

the Ionization smoke detectors were probably responding more to the

submicron (nonvlslble) smoke particles coming from the flaming combustion than to the visible smoke. In one test, which was discarded, the

shredded paper went immediately into flaming combustion, with negligible

production of smoke, and only the two ionization chamber smoke detectors

responded to this fire.

In figure 10, which shows the results of fire test No. 10, the peak

of the smoke is shown occurring about 45 seconds after detector actuation. Problems were encountered in starting the recorder for the smoke

density meter precisely at the same time as ignition. This accounts for

the 45-second offset. In all likelihood, this figure should have re- sembled the figures for fire test Nos. 1, 2 and 3.

4.2. Test Series No. 2 - Polystyrene

This series included test fire Nos. 8, 9 and 27. The polystyrene

fires produce stringy, black smoke particles. It was thought that the

photoelectric detectors, all of which operate on the scattered-light

principle, might have problems with the black smoke because of its poor

light-scattering properties. Such was not the case as can be seen in

figures 8, 9 and 26. Only one photoelectric detector did not alarm and

this was detector "G" in test No. 27. This detector was the least

sensitive of any of the photoelectric detectors tested, having a nominal

sensitivity in terms of light obscuration of 8.2%-m""l (2.5%ft"'^). This

may explain its nonoperation in test No. 27.

4.3. Test Series No. 3 - Gasoline - 100 cc

This series included test fire No. 6. The 100 cc of gasoline was a mistake in that it should have been 200 cc per UL-167. Regardless of

this, all of the photoelectric detectors responded well before the peak

smoke concentrations were reached.

Open-burning gasoline fires produce copious quantities of sooty,

black smoke as can be seen from the graph of the smoke buildup. The

black smoke did not appear to pose a problem to the photoelectric smoke

detectors although again detector "G" was slower to respond than the

other photoelectric smoke detectors.

4.4. Test Series No. 4 - Gasoline - 200 cc

This test series included test fire No. 7. The only difference

between this test series and the one preceding is the use of 200 cc of

gasoline as Opposed to 100 cc in the prior test series. The peak smoke

density was about the same although the total quantity of smoke, the

average smoke velocity and the carbon monoxide maximum were slightly

higher.

12
4.5. Test Series No. 5 - One Wood Brand

This test series included test fire Nos. 4 and 5. The UL-167

requirement for ignition of this wood crib is by the use of 100 cc of

ethyl alcohol. As can be seen from the smoke graphs in figures 4 and 5,

there is very little visible smoke. As a consequence, only one of the

photoelectric detectors responded in test No. 4 and only two photoelectric

smoke detectors responded in test No. 5. Both of the ionization chamber

detectors responded.

4.6. Test Series No. 6 - Two Wood Brands

This test series included test fire Nos. 11 and 12. This test

series differed from No. 5 above in that two wood brands (cribs) were

used, one stacked on the other," in an attempt to produce additional

visible smoke. As was expected, additional visible smoke was produced.

It was sufficient to activate all of the photoelectric detectors, except

detector "G" in test fire No. 11.3

It was noted, during the course of this test, that the ignition

source of 100 cc of alcohol took more than 2 minutes to be consumed. It

was apparent that the alcohol flames were consuming much of the visible

smoke from the wood crib, particularly during early stages of the test

fire.

4.7. Test Series No, 7 - Two Wood Brands

This test series included test fire Nos. 13, 14 and 21. This test

series was the same as test series No. 6 in that two wood brands were

used. But instead of 100 cc of alcohol as an ignition source, 25 cc were uised. The pan for the alcohol was reduced to 90 mm (3-1/4 in)

diameter to prevent the flames from coming out around the edges of the

wood crib.

As was expected, the quantity of visible smoke increased significantly. The quantity was sufficient to activate all of the photoelectric

detectors except for detector "D" (test fires 13 and 14) which had a faulty timer.

4.8. Test Series No. 8 - One Wood Brand

This test series included test fire Nos. 22 and 23. In this series

of tests, the decision was made to return to one wood brand and to use

10 cc of alcohol in the smaller pan as the ignition source. The results,

which are shown on figures 21 and 22, indicated a large increase in the

The difference between the detectors' response time and the smoke peak

was due to the timing problems previously noted under test series No. 1.

13
peak optical density of the smoke. In fact, the peak is similar to the

peaks obtained with the shredded paper, except that those from the wood

brands are not quite as sharp. All the photoelectric detectors responded

well to this test series.

4.9. Test Series No. 9 - Wood Brand on Hot Plate

This test series included test fire No. 15. This test series was

an attempt to produce smoldering combustion of the wood brand by placing

it on a preheated hot plate. Unfortunately, the wood brand flamed immediately as the hot plate surface was above the auto-ignition temperature

for wood. Very little visible smoke was produced. As a result, only

the two ionization chambers responded.

4.10. Test Series No. 10 - Polyurethane - Two Pieces

This test included test fire No. 16. The test was an attempt to

duplicate one of the test fires used in Europe to test smoke detectors.

The polyurethane flexible foam burned in a flaming mode producing

a finely-divided black smoke. The buildup and decay curve was one of

the smoothest of all the test series. In this test series, the response

time of the smoke detectors was spread more than in any of the other

tests. The photoelectric smoke detector "G" did not respond.

4.11. Test Series No. 11 - Polyurethane - Three Pieces \

This test series included test fires 17A, 19 and 24. Three pieces

of polyurethane flexible foam were burned in this test series as opposed

to two in test series No. 10. It was anticipated that more visible

smoke would be produced with three pieces of polyurethane as opposed to

two. In test fire Np. 17A, the quantity was somewhat larger, though the

peak or maximum optical density of the smoke was about the same as with

two pieces of polyurethane. The spread of alarm times for the detectors was also similar to test series No. 10 with two pieces of polyurethane.

In test fire Nos. 19 and 24 both a greater quantity of smoke and a higher peak optical density were observed. Another type of polyurethane

foam was used in test fire Nos. 19 and 24 as opposed to test fire No.

17A.

At the time of the tests, it was thought that the two polyurethane

foam types were equivalent. But a close analysis of the results indicates the second polyurethane foam (test fire Nos. 19 and 24) may have

produced more smoke than the first foam (test fire No. 17A)

Again, as in test series No. 10, the photoelectric smoke detector

"G" did not respond. It can be reasonably deduced that the concentration

14
of the black smoke within the detector sensing chamber of this detector

was not sufficient to produce alarm response.

4.12. Test Series No. 12 - Polyurethane - One Piece

This test series includes test fire Nos. 25 and 26. In this test

series, only one piece of polyurethane flexible foam was used. The

maximum optical density of the smoke produced was similar to the preceding

tests though the quantity was less. The response of the detectors was

similar also, and again, photoelectric detector "G" did not respond.

4.13. Test Series No. 13 - Smoldering Cotton

This test included test fire No. 20. In this series, an attempt was made to produce a test fire of smoldering cotton by heating a quantity of raw cotton in a pan on a hot plate. It has been reported [5] that in this

type of fire, photoelectric smoke detectors are significantly quicker to

respond than ionization chamber smoke detectors.

It was quite difficult to produce detectable quantities of smoke from

the smoldering cotton at the detector site. At first, the smoke from the

cotton layered about halfway to the ceiling. Finally, after 25 minutes or

so, the smoke began to rise to the ceiling and move out towards the detectors.

The results are interesting. First, the response times of the

detectors were spread out significantly. The two wallmount, singlestation photoelectric detectors "D" and "E" were the slowest to respond.

All photoelectric smoke detectors, with the exception of "C", ultimately

responded. Detector "C" uses a light source for detection which lies in

the infrared wavelength while all of the other photoelectric detectors

have light sources in the visible region of the electromagnetic spectrum.

This may have had some effect on its response to the smoke from the

smoldering cotton.

One of the ionization chamber smoke detectors did not respond. This

was detector "H" which is a single-station, residential variety of detector. Somewhat unexpectedly, the other ionization chamber smoke detector

did respond and only shortly after the two most sensitive photoelectrics

One possible explanation for this is that the detector was set near its

most sensitive setting. This, coupled with the fact that this detector is one of the more sophisticated ionization chamber smoke detectors on the

U.S. market, may have accounted for its good responsiveness to the smoldering cotton fire.

15
4.14. Carbon Monoxide

As described in paragraph 2.2.3., peak carbon monoxide concentrations

were recorded at the detector location. These measurements were taken for

future correlation. In the shredded paper fire tests (Nos. 1, 2, 3 and

10) , there appears to be a direct correlation between the peak carbon

monoxide concentrations and the quantity of smoke produced.

This relationship is again apparent in the single wood brand tests.

In tests 4 and 5, where 100 cc of alcohol was used as the igniter, little

smoke was produced and the peak CO averaged 50 ppm. In tests 22 and 23,

where 10 cc of alcohol was used as the igniter, much more smoke was produced and peak CO averaged 122 ppm. In the tests with two wood brands,

the first series with 100 cc of alcohol (tests 11 and 12) and the second

series with 25 cc of alcohol (tests 13, 14 and 21), there were no significant differences in the peak CO concentrations. The reason for this is

not known.

Very little CO was produced in the polystyrene tests. Peak CO con- centrations ranged from 15 to 18 ppm. In these tests only 57 g (2 oz) of

polystyrene was consumed. This may have been a factor in the low peak CO

concentrations. No significant trends were noted in the peak CO concentrations recorded in the other tests.

From time to time, the question arises as to how effective a fire

detector would be based on carbon monoxide sensing as opposed to detection

of smoke particulates as done by conventional smoke detection. Assuming

first that a carbon monoxide detector for home use can be developed that

would be both practical and cost competitive with conventional smoke

detectors, the next question would be what sensitivity range would be

necessary. Looking at the results of the fire tests, peak CO concentrations ranged from 15 ppm to 125 ppm. The lowest CO peaks were recorded in

the polystyrene fires and the highest in the single wood brand fires using

10 cc of alcohol as the ignition source.

Reports of ambient CO background levels have indicated levels in excess of 25 ppm are present in some of our urban areas. In view of this,

a lower sensitivity level of 50 ppm for a CO detector seems like a good

place to start.

Fourteen of the 26 fires or 54 percent, generated CO peaks in excess

of 50 ppm. This means that 46 percent of the test fires would not have

been detected with a CO detector set at a 50 ppm alarm point. Ignoring

detectors "J" and "K", the performance of the poorest photoelectric

detector was detection of 14 fires or 54 percent. The best photoelectric

detector performance was 25 of the 26 fires or 96 percent. The poorest

performing ionization chamber detector detected 25 of the 26 fires or 96

percent.

16
Assuming an alarm point of 25 ppm for the carbon monoxide detector,

such a detector would have detected 19 of the 26 test fires or 73 percent.

A CO detector set at an alarm point of 25 ppm therefore would have a detection capability comparable to most of the photoelectric smoke detectors tested in this program with regards to these test fires. Coupled

with this increased responsiveness would be a possible problem of an increased number of false alarms to urban ambient CO levels. But it would

appear that a sensitive CO detector may be effective as a home smoke

detector, at least based on the types of fires conducted for this test

series.

4.15. Average Air Velocities

The average air velocities ranged from a low of 5.2 m/min (17 ft/min)

for the single wood brand, 10 cc alcohol tests (tests 22 and 23) to a high

of 42.7 m/min (140 ft/min) for the wood brand on the hot plate (test 15

with wood brand flaming). On the whole, the average air velocities

recorded were higher than had been anticipated.

It is interesting to note that the average air velocities for the

four types of fires used by UL for judging detectors under UL-167 were:

shredded paper, 18.3 m/min (60 ft/min); wood brand, 12.2-21.3 m/min (40-

70 ft/min); gasoline, 15.9 m/min (52 ft/min); and polystyrene, 18.3-21.3

m/min (60-70 ft/min). Work at the National Bureau of Standards has indicated that velocities of these orders are usually sufficient to overcome

the smoke entry problems of most smoke detectors.

A note of caution is in order here. The method of measuring the

average air velocity past the detectors was not designed to be very accurate. As described in section 2.5, the method used to determine the

average air velocity was to time the smoke front between the two smoke

density photometric units. The average air velocities are approximations

and should be treated accordingly.

4 . 16 . Temperatures

As described in section 2.2.2; the temperatures at the ceiling,

directly over the fire and at the detector site, were recorded for each

of the 26 test fires. Temperatures over the test fires ranged from a low of 18 °C (64 °F) to a high of 50 °C (122 °F) . Temperatures at the

detector site ranged from a low of 12 °C (54 °F) to a high of 27 °C

(81 °F). Ambient room temperatures during the test series ranged from

10 °C (50 °F) to 15 °C (59 °F) . Fixed- temperature heat detectors have a nominal setting of between 54 °C to 60 °C (130 °F to 140 °F) . From the

temperature data recorded, it is apparent that the temperatures generated

both over the fire and at the detector site would not have been sufficient to operate a fixed-temperature heat detector, but most of the

photoelectric and ionization chamber smoke detectors were able to detect

nearly all of the fires.

17
A. 17. Photoelectric Smoke Detector "J"

Photoelectric smoke detector "J" was a single-station smoke detector,

approved by UL under UL-168 [2]. Analysis of this detector at NBS has

shown that it has great difficulty in accepting and sensing slow-moving

smoke. It was included in the test series in order to compare its performance against photoelectric smoke detectors having little or no smoke

entry problems. In order to bias the results in favor of this detector,

it's alarm threshold was set by the manufacturer at 0.5 percent per foot

in terms of light obscuration. This setting was confirmed at NBS prior to

and after the test series. The normal sensitivity setting of photoelectric smoke detectors is on the order of 1 to 2 percent per foot (3.3 to

6.6%-m"l).

As can be seen from the tabulated results in table 3, this detector

responded to only two of the 26 test fires (Nos. 1 and 21). It would

appear from these results that photoelectric smoke detectors with significant entry problems would not be able to detect the types of fires

utilized in this test series.

5. SUMMARY AND CONCLUSIONS

As described in section 1, the purpose of the tests described in

this report was to determine if photoelectric smoke detectors can respond

to the four full-scale fires used by UL to evaluate ionization chamber

smoke detectors. Seven of the eight photoelectric smoke detectors selected

for the test series were chosen on the basis of their good response to

slow-moving smoke under laboratory conditions, i.e., those detectors

exhibiting little if any entry problems. The eighth photoelectric detector

included in the test series detector "J", a detector which exhibits significant problems in sensing slow-moving smoke, was included for comparison

purposes.

It was the opinion of the authors that the seven photoeletric smoke

detectors could, in all likelihood, satisfactorily detect the four standard

test fires, albeit, with perhaps some slight modifications to the test

fires. If the results of the tests confirmed this opinion, then it should

be possible to combine the requirements of UL-167 and UL-168 into one

standard. One result of this combination of standards would be the new

requirement for all photoelectric smoke detectors to detect the four fullscale fires before approval, a requirement now required of ionization

chamber smoke detectors and all detectors using new sensing methods, other

than the photoelectric principle.

If photoelectric detector "J" had also managed to detect the four

standard test fires, then either of two conclusions could have been

drawn. One conclusion would have been that the standard test fires are not small enough to separate detectors with marginal performance from

better performing detectors. The other conclusion would have been that

18
the laboratory test procedures, which show large differences in the performance of various smoke detectors to slow-moving moving smoke, are not

realistic as these differences are not reflected in the performance of

detectors in real fire conditions.

Looking first at the shredded paper test series (test series No. 1 —

test fires 1, 2, 3 and 10), all of the seven photoelectric detectors

responded well within one minute, as did the two ion chambers, for test

fires 1, 3 and 10. In test fire 2, very little smoke was produced as the

paper flamed before significant quantities of smoke were produced. As a consequence, only photoelectric detector "B" responded. As discussed

earlier in this report, there is a problem in fluffing the shredded paper

to produce a significant quantity of smoke after ignition, but prior to

flaming of the paper. The photoelectric detector "J" and the TGS sensor

"K" detected only test fire No. 1.

In the polystyrene test series (test series No. 2 — test fires 8, 9

and 27), all seven of the photoelectric detectors and the two ionization

chamber detectors responded within one minute except for photoelectric

detector "G" in test fire No. 27. This detector, while having very little

entry problem, had the least sensitive setting of any detector. Test fire

No. 27 required slightly longer detection times from all detectors and

this may have had a bearing on the non-response of detector "G". The

reason for the longer response time is not readily obvious as the smoke

buildup was essentially the same in all three tests. Detectors "J" and

"K" did not alarm to any of the three polystyrene fires.

In the gasoline test fires (test fires 6 and 7) , all seven photoelectric detectors as well as the two ionization chamber detectors responded

in under two minutes except photoelectric detector "G" in test fire No. 7 which responded in 132 seconds. Detectors "J" and "K" did not respond.

Test fire No. 6 was with 100 cc of gasoline although UL-167 specifies

200 cc. Test fire No. 7 was with 200 cc. No significant difference in

detection times were noted between these two tests. In fact, the detectors' responses were slightly faster in the 100 cc test than in the 200

cc test. The lack of difference is understandable as liquid fuel fires are surface-area-controlled fires. The result of adding additional fuel

would be to lengthen the burning time and increase the total quantity of

smoke but would have little effect on the peak smoke concentration or rate

of buildup. The graphs of the smoke buildup appear to confirm this.

In the single wood brand test series (test series No. 5 — test fires

4 and 5), only photoelectric detector "B" was able to detect both fires.

Photoelectric detector "F" was able to detect test fire No. 5, but not

test fire No. 4. The reason for the non-response of the other photoelectric detectors is reasonably obvious from the graphs of the smoke buildup.

Very little visible smoke was developed in these two tests. Slightly

19
more smoke was produced In test fire No. 5 than test fire No. 4 and this

would account for the response of detector "F" to this latter test fire,

but not to the former.

In an attempt to improve the performance of the photoelectric detectors to the wood brand fire, the number of wood brands was increased to

two (test series No. 6 — test fires 11 and 12). The ignition source of

100 cc of alcohol remained the same, A bit more smoke was produced than

with a single wood brand. This was sufficient to alarm all the seven photoelectric detectors except detector "G" in test fire No. 11 and detector "E" in test fire No. 12.

It was noted that the 100 cc of alcohol burned for over two minutes.

A careful scrutiny of the alcohol flames revealed that the flames were

consuming the visible smoke coming from the burning wood brands. It was

decided to reduce the quantity of the alcohol to 25 cc, but to retain the

two wood brands. The results of this experiment are shown in test series

No. 7 (test fires 13, 14 and 21). A greater quantity of smoke was produced with higher peak concentrations. As a result, all seven photoelectric detectors responded in under two minutes except for detector "D"

which was experiencing clock timer malfiinctions

It was decided to try one wood brand again. Instead of using 25 cc

of alcohol for ignition purposes, the quantity was reduced to 10 cc. The

results are shown in test series No. 8 (test fires 22 and 23). With this

combination, one wood brand, and 10 cc of alcohol for ignition, some interesting results were obtained. The 10 cc of alcohol provided a very

low order ignition fire so that ignition of the wood was delayed for well

over a minute. Then the wood brand began to generate profuse amounts of

smoke for about thirty seconds. At this point open flaming was established

and the visible smoke diminished. All seven photoelectric detectors

responded within a 38-second interval and within 130 seconds from ignition

of the alcohol.

The ionization chamber detectors responded throughout these series

of experiments with the wood brands. Their margin of superiority, in

terms of earlier response time, tended to diminish with decreasing amounts

of the alcohol igniter which was, in turn, producing more visible smoke.

This was to be expected.

Photoelectric detector "J" responded to only one of the test fires

in this wood brand sequence. TGS sensor "K" did not respond to any of

the wood brand fires and no indication was noted on its meter in any of

these test fires.

With respect to the four tests specified in UL-167 and the response

of photoelectric smoke detectors to these test fires: the following con- clusions can be made. (1) Most presently available photoelectric smoke

detectors would be unable to pass the wood brand fire test as presently

specified in UL-167 because the test fire produces very little visible

smoke. Since it is the purpose of the test to check response of detectors

20
to wood smoke, and since a condition where the wood brand Is forced into an immediate flaming mode by the alcohol is somewhat unrealistic in practice, it seems reasonable to modify the test to produce more visible

smoke. If the wood brand test were modified, using less alcohol for

ignition, as was done to these series of experiments, then more visible

smoke would be produced. The results would be that many of the photoelectric detectors could then meet this test requirement. The suggested

modification to this test to permit its use for evaluating photoelectric

smoke detectors would be to continue with the one wood brand but reduce

the alcohol igniter from 100 cc to 10 cc. The size of the metal container

for the alcohol should be reduced to a small, shallow pan having a diameter of approximately 90 mm (3-1/2 in). (2) The shredded paper test fires are extremely operator-dependent, as discussed in section 4.1. It is

quite difficult to obtain repeatability between tests and it would be

almost impossible to obtain reproducibility between laboratories. If the

changes suggested above are made to the wood brand series, then the shredded paper test series may become redundant. Both the wood brand and the

shredded paper test series are testing detector response to the same material, that is, to a burning cellulosic. (3) The gasoline test fire

series of UL-167 is a satisfactory method, as now conducted, for the

evaluation of photoelectric smoke detectors based on the results of experiments. Therefore, no modification is needed in this test series to accom- modate photoelectric smoke detectors. (4) The polystyrene test fire

series of UL-167, while satisfactory in terms of detectability by the

photoelectric smoke detectors (with one exception) , produced a smoke

buildup at the detector location with two pronounced peaks. The reason

for this is not known though it may be related to the use of 50 cc of

alcohol as an ignition fuel. Sufficient time was not available to investigate methods of producing a smoother smoke buildup such as experimenting

with different quantities and configurations of alcohol ignition. The one exception mentioned above was detector "G" in test No. 27. As mentioned

previously, this detector was the least sensitive of any of the photoelectric detectors tested. Although the detector has no appreciable smoke

entry problem, it may be that it's preset sensitivity level was too high • to detect the characteristically black smoke of polystyrene. (5) The

polyurethane test fires were included in the test series as this material

is used in several of the European countries as a standard test material

for the evaluation of smoke detectors. The results were good enough to

suggest the possibility of this material as a replacement for the polystyrene test material. Additional experiments will be necessary, however,

to establish the quantity, configuration, specific type, and density of

polyurethane to be used. In addition, it was apparent that in the experiments reported herein the detectors with sensitivities of less than 6.6%- m~ (2%ft~"'") will have difficulty with this test regardless of how excellently they respond to slow-moving smoke. (6) Photoelectric smoke detectors, found to have poor smoke entry characteristics at low air velocities,

will respond to few, if any, of the UL-167 test fires. The example of

this is the performance of detector "J", a single-station smoke detector

widely sold as a residential smoke detector. The detector was chosen as being representative of a class of photoelectric smoke detectors exhibiting

21
poor response characteristics to slow-moving smoke when tested in

laboratory-type smoke test tunnels. This suggests that the test fires

used are sufficiently discriminatory in this regard and that the smoke

entry characteristics measured in laboratory smoke test tunnels at low air

velocities do give a reasonably accurate portrayal of the detector's

response to real, but small fires (7) The lack of responsiveness of the one TGS sensor (detector "K") included in the test series to fires with

relatively complete combustion should be noted. In open flaming fires,

very little unburnt hydrocarbons and carbon monoxide are produced (the two

main combustion products to which the TGS sensor is sensitive) . It had

been thought that the TGS sensor would respond to the smoldering cotton

fire. But even here, only a slight analog output was noted which was far

short of alarm threshold of the detector. (8) In order for a fire detector employing a carbon monoxide sensor to respond in a comparable manner

to conventional smoke detectors, detection of 73% of the test fires would

have been necessary. This would have required an alarm threshold to CO of

approximately 25 ppm. Since concentrations of CO in excess of this are periodically experienced in urban areas, a detector with this alarm threshold might experience an undue nuinber of false alarms. (9) In tests where

open flaming and little visible smoke predominated, the ionization smoke

detectors demonstrated their superiority over photoelectric smoke detectors. In those tests where open flaming and significant quantities of

visible smoke were produced simultaneously, neither type of detector

indicated any significant margin of superiority. In the one truly smoldering fire, the photoelectric smoke detectors demonstrated their superiority over ionization smoke detectors to this type of fire. The obvious

conclusion is that neither detector does well on all types of fires in

terms of early response. If one could predict with some measure of cer- tainty the type of fire to be given emphasis for detection, the appropriate detector could be selected. If this prediction is not practical, then

either type of detector should be able to satisfy the detection needs.

The choice of which to use in this case has to lie with other considerations, such as cost, reliability, esthetics, and the like.

6. ACKNOWLEDGEMENTS

The authors wish to thank Underwriters' Laboratories for making

their smoke detector test facilities available for the test work. The

authors gratefully acknowledge the assistance of Robert Pettinger and

Harold Davidson of UL's staff in conducting the test series.

7. REFERENCES

[1] Custer, R. L. P. and Bright, R. G., Fire Detection: The State-ofthe-Art, Nat. Bur. Stand. (U.S.), Tech. Note 839, (June 1974) U.S.

Government Printing Office., Washington, D.C., SD Cat. No. C13.46:

839; $1.25.

22
[2] Standard for Smoke Detectors, Photoelectric Type, for Fire Protective

Signaling Systems, UL-168, Underwriters' Laboratories, Inc., Northbrook,

II. 60062 (March 31, 1971) - Also as ANSI A131. 41971, American National

Standards Institute, 1430 Broadway, N.Y. 10018.

[3] Standard for Smoke Detectors, Combustion Products Type, for Fire

Protective Signaling Systems, UL-167, Underwriters' Laboratories, Inc.,

First Edition, November 29, 1974.

[4] Bukowski, R.W. and Bright, R.G., Some Problems Noted in the Use of

Taguchi Semiconductor Gas Sensors as Residential Fire/Smoke Detectors,

Nat. Bur. Stand. (U.S.), NBSIR 74-591, (Dec. 1974).

[5] Custer, R. L. P., Detector Actuated Automatic Sprinkler Systems - A Preliminary Evaluation, Nat. Bur. Stand. (U.S.), Tech. Note 836,

(July 1974), U.S. Government Printing Office, Washington, D.C., SD

Cat. No. C13.46: 836, $0.65.

USCOMM-NBS-DC

23
N

Not to scale

Notes:

1,2 Detector Board Locations

A,B Smoke Density Measuring Equipment

F Fire Location

Figure 1. Fire test room floor plan.

24
1

10 -

1 2 3 A 5 TIME (MIN)

PHOTO

ELECTRIC

DETECTORS

A •

B • , -r e

E •

-r •

G •

IONIZATION

DETECTORS

H

I 1

CO LEVEL , iPPM 80 i AVG VELOCITY a 70 (21. 3-^) TEMP OVER FIRE

TEMP AT UET 'C 18 TEST NO: 1 Conb: 1/2 // Paper IGN: :iatch Date: 2/13/74

a. VELOCITY IN FEET PER i-IIN (METERS PER MIN)

Figure la. Results of fire test No. 1.

25
,3

.25

.2

.15-

.1"

.04

.03'

.02'

.01-

25

20.

15-

H

O

g

aitag

Uio

pi

[I]

PL4

o

M

O

30

40

50

60

S '0

»4

90

TIME (MIN.)

PHOTOELECTRIC

DETECTORS

A 1

C

! j> 1 E

! F

G 1 lONIZATIO:-^ DETECTORS

a

' •

I •

CO LI'A'iCL L'l-.\

1 AVG Vl.LOCITY a 60(18.29) 1 tLi-IP OViiil Fiit£ »C WA

TiOT-Tnnjti' »( HA TEST NO: 2 COMB: 1/2 // Paper ICN: Match DATE: 2/13/74

a. VELOCriy lU FEET PLR IIIU (METERS PER Mlt.') Figure 2. Results of fire test No. 2.

26
1

.3-

.25-

.2^ M

e .15' M

:^a

H

o .1-

.05-

.04'

.03"

.02-

• UX

25<

20.

15-

H

O

M

^ 10-

g

zoM

«

O

5

•

4

•

3'

2*

1-

PRECENT

TRANSMISSION

OVER

5

FOOT

(1.52

METER)

BEAM

o

o

o

o

o

o

o

1 2 3^4 5 TIME (MIN.)

PHOTOELECTRIC

DETECTORS

A • 1 "T .. . , f ,1 C •

D •

E •

•

G •

lONIZATIOil

DETECTORS

H •

1 •

CO LliVtL Pi';! 63 AVG VliLOClTV a 60(18.29) i TEMP OVER FIRE \ 46 1 il " , TEST NO: 3 COMB: 1/2 Paper IGN: Match DATE: 2/13/74

a. VELOCITY lU FEET PER HIiJ (iIETERS PER MIN)

Figure 3. Results of fire test No. 3.

27
25

.3-

.25-

.2

e

-15

.r

.05

.04

.03

.02

.01-

20.

15-

H

o2

H

M

UM

«

O

30

s 40

50

60

70

90

1^

TIME (MIN.)

PHOTOELECTRIC

DETECTORS

A

B •

CD

E

.F 1 G

1 IONIZATION

DETECTORS

li • > 1 1 •

CO LEVKL TT'ii 45 AVU VELUCIIVr a 40a2.20)

llil-U' UViiR FIliE 50 j Tt.Mi' AT 27 TEST NO: 4 COMB: Wood -rand ICN: lOOcc Alcohol DATE: 2/13/74

a. vrrnnTTV lij feet per mil (;ieters per miu)

Figure 4. Results of fire test No. 4.

28
.3"

.25

.2

25

20.

15-

10'

30

40

50

60

70

80

3 4 TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A

B •

CD

E

F •

G IONIZATION

DETECTORS

H •

I •

CO LEVEL 56 AVG VLLOCITY a 70(21.34) TEMP OVER FIRE *C

TEl-LP Al' "C 21 TEST NO: 5 COMB: Wood Brand IGN:iOOcc Alcohol DATE: 2/13/74

a. VELOCITY IN FEET PER MIN (METERS PER MIN)

Figure 5. Results of fire test No. 5.

29
a. VKLOCITY IN FI:ET PER MliJ (IIETEIUS PER Hill) Figure 6. Results of fire test No. 6.

30
PHOTO- ELECTRIC

DETECTORS

A •

•

CD ;

, E •

F •

G Jt 1 IONIZATION

DETECTORS

H •

I - CO LKVEL 29 AVG VELOCITY a 52(13,85)

TEMP OVLR FIRE 'c 73 itMP AT di;t 'c 15 TEST NO: 7 COMB: 200cc Gasoline IGN: :^tch DATE: 2/13/74

VELOCITY IN FEET PER WIN (^ETERS PER MIN)

Figure 7, Results of fire test No. 7.

31
.3-

.25-

.2

ei

r: -IS- MM

1

OM

H

o .r

.05-

.04'

.03'

.02'

.01-

25-

20.

15-

HO

g

oi(d

Oi

^ 10- M

S3o

M

O

C/l CQO

5

•

4

•

3"

2

'

1*

30

biH

50

rHH

O^ 60

Pi>O

z

oM

t/5 w 70 wH

90

• -

-

i 1 2 3 4 5 TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A • 1 B • t C • ! D

E • 1 ¥ i

^

1 G • 1 IONIZATION

DETECTORS

H • 1 I • 1 CO LEVEL 18 •

1 AVG VELOCITY a 60(18.29) ! TFi-lP OVlU YUUi MA ! TLl-Lf AT uliT i<A TEST NO: 8 COMB: 2oz Polystyrene IGN: 50cc Alcohol DATE: 2/13/74

a. VELOCITY IH FliET PER Mlli (METERS PER MIN)

Figure 8. Results of fire test No. 8.

32
1 2 3 / TIME (MIN.)

» 5

THOTO- ELECTRIC

DETECTORS

A • 1 B •

C • 1 D

E •

F

G •

IONIZATION

DETECTORS

il r '

' .11 1 4 •

I CO LEVKL t'l';; 15 • 1 AVG VbiLOClTY a 60(18.29) ! TEi'-U' OViiR Fil'Ji 'c NA i TtUP AT' DL'T

' :;a

] TEST NO: 9 COMB: 2oz Polystyrene IGN: 50cc Alcohol DATE: 2/13/74 )

a. VELOCITY IN FEET PER MIN ((DCTERS PER MIN)

Figure 9. Results of fire test No. 9.

33
.3

.25

06w

•2,

^ .15

25

20.

15-

H

O

s

10-

30

40

50

60

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A •

B • 1 C L-h ^

^ i> 1 E •

F •

G •

IONIZATION

DETPXTORS

n

I • 1 CO LEVEL AVG VELOCITY a 60(18.29)

TEMP OVER FliO:. NA

TLMJ' AT UET \ HA TEST NO: 10 COMb: 1/2 // Paper IQIs Match DATE: 2/14/74

a. VELOCITY IN FEET PER MliJ (IILTERS PER MIM)

Figure 10. Results of fire test No. 10.

34
PUOTO- ELECIRIC

DETECTORS

A • 1 i • 1 C • 1 D • 1 E • ! F • 1 G

1 lONIZATIO;,' DETECTORS

ri • 1 I • 1 CO LtVHL so.

] AVG VilLOClIY 84(25.61) 1

Tt-Ii' OVLR FIH£ 30 1 ityLt" Ai ul-l 15 1 TEST NO: n COMB; 2 Wood Brands IGN: lOOcc Alcohol DATE: 2/14/74

a. VELOCITY IN FEET PER MXIJ (METERS PER MIN)

Figure 11. Results of fire test No. 11.

35
.3-

.25

.2

e

.15

M

CO

.r

.05

.04

.03

.02

.01

25

20.

13-

O

2

OSU3g

pa

z

oI

u

on«

O

2

11

30

40

50

60

a

70

80

90

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A •

B •

C •

D •

E

F •

G •

IONIZATION

DETECTORS

n • 1 I • ' . 1 CO LEVEL r'i'.'-', 70 AVG VELOCITY a

TE>Q' OVER FIliK 'c MA TEMP AT Dl^T NA TEST NO: 12 COMB: 2 Wood Brands IGN:ioOcc Alchol DATE: 2/14/74

a. VELOCITY IN FEET PER MlN (METERS PER MIN)

Figure 12. Results of fire test No. 12.

36
.3

.25

.2

w

M

CdO

:^o

H

OiO .1

.05

.04

.03

.02

.or

25

20.

15-

HO

g

oiu

H

ZM

^ 10 u

30

AO

50

60

70

2

H 80 2

90

1 2 3-^4 5 TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A •

B • ! C • 1 D 1 E • i F •

G •

IONIZATION

DETECTORS

a • t I •

CO LEVEL 70 1 AVG VELOCITY a 56(17.07)

TE;-a' OVER FlilE 25

"C 14 TEGT NO: 13 COMB: 2 Wood Brands 1(^4: 25cc Alcohol DATE: 2/14/74

a. VELOCITY IN FEET PER HIIJ (ilETEHS PER MIN)

Figure 13. Results of fire test No. 13.

37
.3

.25

.2

S

.15

.1"

.05'

.04

.03

.02

.01-

25-

20.

15-

o

5 1

4

30

40

50

60

w 70

90

TIME (MIN.)

PUOTO- ELECTRIC

DETECTORS

IONIZATION

DETECTORS

CO LKVKL Fp: 66 AVG VELOCITY 56(17,07)

TEi-lP OVKK FiliJi 26

14 TEST NO: 14 COMB: 2 Wood Brands IGN; 25cc Alcohol | 2/14/74

a. VELOCITY IN FEET PER MIU (tIETEUi; PER MIN)

Figure lA. Results of fire test No. 14.

38
.3

.25-

.2

eiH

i

M

>• .15

M

.1"

25-

20.

30

15-

10'

5

4 i

40

50

60

P4

70

,y 80

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

IONIZATION

DETECTORS

CO LKVEL AVG VELOCITY 140(42.68)

TE>Q' OVER FIRE 28

TtlHP AT liET IT

TEST NO: 15 COMB: Wood Brand IGN: lOOOW hotplate DATE: 2/14/74

VELOCITY IN FEET PER MIN (METERS PER MIN)

Figure 15. Results of fire test No. 15.

39
.3

.25

25-

20.

15-

O

g

ai04

Cdo

04

o

3O

o

10-

30

40

50

60

70

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

IONIZATION

DETECTORS

CO LEVEL TV: 36 AVG VELOCITY

TLM? OVER F:K£

105(32.01)

AT bl"? 25

13 TEST NO: 16 COMB: 2 pes Polyurethane IGN: lOcc Alcohol DATE: 2/14/74

a. VELOCITY IN FEET PER MIN (METERS PER MIN)

Figure 16, Results of fire test No, 16.

40
.3-

.25-

nSM

S

.15. M

CO

oH

o .1*

.05-

.04-

.03"

.02'

.01-

25-

20.

15-

H

O • g

u

10-

ZM

z

o

Ms

o

COno

5

•

4

•

3

'

2

1-

30

S"M

H

" 50

r>4 tri

r-i H

o

O^ 60

ci>

O

z

o

C/2 - 70 s

COH

90

•

-

1 2 3^4 5 TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A •

B •

C •

D

E •

F •

G IONIZATION

DETECTORS

£1

I sx • ^ CO LEVEL ! AVG VLLOCIXV; a 120(36.59)

j Ti:;i? OVER FI,d:

-T~;

L 27 ; '^E^1^' AT DeT

' s , 15 TEST NO: 17A C0M!3: 3pcs Polyurethane IGN: lOcc Alcohol DATE: 2/14/74

a. VELOCITY W TEKT PER MIJ (IIETERS PER Mil!) Figure 17. Results of fire test No. 17a.

41
.3'

.2

H

(A

uM

Ho .1'

.05'

.04

.03

.02

.01-

25

20.

15-

HO

g

M(l4

3

U

ton

o

10-

30

40

50

60

70

»4

90

2. TIME (MIN.)

PHOTOELECTRIC

DETECTORS

IONIZATION

DETECTORS

CO LEVEL 7T> 60 AVG VELOCITY 120(36.59) TEMP OVER FIRE

TtlhtP AT uL'T 28 "IT

TEST NO: 19 COMB: 3 pes Polyurethane IGN: lOcc Alcohol DATE: 2/14/74

a. VELOCITY IN FEET PER mN (METERS PER MIN)

Figure 18. Results of fire test No. 19.

42
.3

.25

.2

ooM

H

O .1

.05

.04

.03

.02

.01'

25.

20

15-

10

30

40

50

60

70

80

90

27 28 29 TIME (MIN.)

30 31

PHOTOELECTRIC

DETECTORS

A •

B •

CD •

E •

F •

G •

IONIZATION

DETECTORS

U 1 I •

CO LEVEL Pi'.M 20 1 AVG VELOCITY a 24(7.32) 1 TEl-IP OVER FIRE 10 1 Tli-u' at UET 'c 10 TEST NO: 20 COMB: Raw Cotton IGN: Hotplate DATE: 2/14/74

a. VELOCITY IN FEET PER MIN (^^•:TERS PER MIN)

Figure 19. Results of fire test No. 20.

A3
.3-

.25

.2

S

.15

.1"

.04

.03*

.02'

.01-

25

20.

15-

u^ 10' M

1^

i

30

40

50

60

70

80

90

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

IONIZATION

DETECTORS

CO LEVEL 70 AVG VELOCITY 35(10.67) TEMP OVER FllUi TtMi' AT DET

33

25 TEST NO: 21 COMB: 2 Wood Brands IGN: 25cc Alcohol DATE: 2/15/74

a. VELOCITY IN FEET PER MIN (METERS PER MIN)

Figure 20. Results of fire test No. 21.

AA
.3-

.25-

.2 H

i

lAH

e .15

M

M

25

20,

15-

.05

.04

.03

.02 .OH

30

AO

50

60

70

80

90

\

\

^

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A •

•

C •

£ •

? •

G •

IONIZATION

DETECTORS

H • " 1 I • i CO LEVEL pp:; 120

AVG VELOCITY a 1.7 (S. 18^ ! TEM? OVER FIRE 'c 31

'im AT bET 'c 18 TEST 'NO: 22 COMB: Wood Brand IGU: lOcc Alcohol DATE: 2/15/74

a. VELOCITY IN FEET PER MIH (METERS PER MIN)

Figure 21. Results of fire test No. 22.

45
.3"

.25-

.2

.1

.05

.04

.03

.02

.01-

25

20.

15-

o

Oo

5

4 i

30

40

50

60

1

90

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

IONIZATION

DETECTORS

CO LEVEL

I

AVG VELOCITY

125

17C5.18)

TEMP OVER FIRE Tm AT bl^T 14 TEST NO: 23 COMB: Wood Brand IGN: lOcc Alcohol DATE: 2/15/74

a. VELOCITY IN FEET PER MIN (METERS PER MIN)

Figure 22. Results of fire test No. 23.

46
25

20

.25-

.2

,15

15-

.1

.05

.04

.03

.02

.01'

o

Ow

n

o

10-

5

4 i

2H

30

40

50

60

70

80

90

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A • 1 • 1 C —? 1 D • 1 £ • i F

1 G 1 IONIZATION

DETECTORS

H •

I • 1 CO Ltl'/EL 60 ! AVG VELOCITY a 168(51.22) 1 TEMl' OVER KIKE 30 1 TEMP AT bL'T 'c 17 1 TEST NO: 24 COMH: 3pcg Polyurethane I^iJ: iqcc Alcohol 2/15/74 |

a. VELOCITV IN FEET PER HIiJ (IIETERS I'ER MIN)

Figure 23. Results of fire test No. 24.

47
.3-

.25-

.2 M

I

tAH

H

M

g

o

A

oM

H

PL4

.05

.04

.03

.02

.01'

25

20.

15-

HO

g

M

g

M

U

0*

oM

D

U

COA

O

30

40

50

50

70

80

90

TIME (MIN.)

PHOTOELECTRIC

DETFCTORS

A •

U •

, C •

D •

E •

F •

G IONIZATION

DETECTORS

H •

I •

CO LEVEL 33 AVG VELOCITY a 120(36.59)

te:u' over Fii'i; 20

TLTli' .iiT LET 13 TUST NO: £5 COllU: Ipc Polyurethane IGN: lOcc Alcohol MTE: 2/15/74

a. VELOCITY IN FEET PER MIN CDiTEKS PER MIN)

Figure 24. Results of fire test No. 25.

48
TIME (MIN.)

PHOTOELECTRIC

DETECTORS

A •

B •

C •

D •

E •

F •

G IONIZATION

DETECTORS

H •

I •

CO LLVKL I'l'M AVG VELOCITY a i 1A0(42.68) ' TEMl' OVER FIRL 17

Ttli-l]* AT m 12 TEST NO: 26 COMB: Ipc Pblyurethane IC-J: lOcc Alcohol DATE: 2/15/74

a. VELOCITY T.U FEET PER MIN (iOn'ERS PER MIN)

Figure 25. Results of fire test No. 26.

A9
.3-

.25-

H

M

oH

P3O

.05-

.04

.03"

.02-

.01

25

20.

15-

30

40

50

60

70

90

TIME (MIN.)

PHOTO- ELECTRIC

DETECTORS

A • 1 3

C •

D • 1 E •

F • i G 1 IONIZATION

DETKCTORS

ii • 1 I •

CO LKVLL Pt';' 18 , : , AVG VKLOCITY a 70(21.34) ! TETl' OVER FIRi: *C 18 : TEFIP AT L)\L'! 12 1 TEST NO: 27 COMB: 2oz Polystyrene ^OHi sqcc Alcohol 2/15/74 |

a. VELOCITY IN FEET PEU MIIJ (inCTERS PER MtN)

Figure 26. Results of fire test No. 27.

50
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 75-700

2. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE AND SUBTITLE

RESULTS OF FULL-SCALE FIRE TESTS WITH PHOTOELECTRIC SMOKE

DETECTORS

5. Publication Date Jxine 1975

6. Performing Organization Code

7. AUTHOR(S)

Richard W. Bukowski and Richard G. Bright

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Taslc/Work Unit No. 4928200

11. Contract/Grant No.

12. Sponsoring Organization Name and Complete Address (Street, City, State, ZIP)

same as No. 9

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.)

In February 1974, a series of full-scale fire tests were conducted to determine

whether photoelectric-type smoke detectors could respond to the same types of fires

used to assess the performance of ionization-type" smoke detectors. The types of

fires employed in the tests are the same as those outlined in Underwriters'

Laboratories, Inc., Standard No. 167. In addition to the UL-167 standard fires,

fires involving polyurethane (flaming mode) and cotton (smoldering mode) were

added to the test series. One detector, utilizing a Taguchi gas sensor (TGS) , was included in the test series for evaluation purposes. The test results indicated

that the better photoelectric smoke detectors, i.e., those having little obstruction

to slow-moving smoke can, in general, detect the same test fires as the ionization

chamber smoke detectors in approximately the same time scale. For the smoldering

cotton fire, the photoelectric detectors were significantly faster than the ionization chamber detectors. The TGS fire detector was unable to detect most of the

test fires.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons)

Fire detectors; ionization chamber smoke detectors; photoelectric smoke detectors; smoke detectors; Taguchi gas sensors.

18. AVAILABILITY [x] Unlimited

1

' For Official Distribution. Do Not Release to NTIS

1

' Order From Sup. of Doc, U.S. Government Printing Office Washineton. D.C. 20402. SD Cat. No. C13

yn Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO. OF PAGES

50

55

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

$4.25

USCOMM.DC 29042-P74