NBSIR 76-1172

A New Test Method for

Automatic Fire Detection

Devices

Richard G. Bright

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

December 1976

Final Report

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 76-1172

A NEW TEST METHOD FOR

AUTOMATIC FIRE DETECTION

DEVICES

Richard G. Bright

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washisngton, D. C. 20234

December 1976

Final Report

U.S. DEPARTMENT OF COMMERCE. Elliot L. Richardson. Secretary

Edward O. Vetter, Under Secretary

Dr. Betsy Ancker-Johnson, Assistant Secretary lor Science and Technology

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting Director
.
PREFACE

This report is an adaptation of a paper presented by the author at the 80th Annual Meeting of

the National Fire Protection Association, on May 18,

1976, in Houston, Texas.

in

CONTENTS

Page

PREFACE iii

LIST OF FIGURES vi

LIST OF TABLES vi

Abstract 1

BODY OF PAPER 2

REFERENCES 13

v
LIST OF FIGURES

Page

Figure 1. Geometry of Detector Test Laboratory ... 14

Figure 2. Position of the Detectors and Measuring

Devices on Ceiling of Detector Test

Laboratory 14

LIST OF TABLES

Page

Table 1. Types of Automatic Fire Detection Devices. 15

Table 2. Proposed Standard Test Fires 16

Table 3. Test Fire No. 1 - Flaming Cellulosic ... 17

Table 4. Test Fire No. 2 - Smoldering Cellulosic. . 17

Table 5. Test Fire No. 3 - Flaming Plastic .... 18

Table 6. Test Fire No. 4 - Flammable Liquid w/

Smoke 18

Table 7. Test Fire No. 5 - Flammable Liquid w/Heat. 19

Table 8. Fire Detector Classification Table —

Typical Results for: Ionization Smoke

Detector 20

Table 9. Fire Detector Classification — Typical

Results for: Photoelectric Smoke Detector 21

Table 10. Fire Detector Classification — Typical

Results for: Heat Detector 22

Table 11. Fire Detector Classification — Typical

Results for: Infrared Flame Detector. . . 23

)

vi
A NEW TEST METHOD FOR AUTOMATIC

FIRE DETECTION DEVICES

Richard G. Bright

Abstract

An analysis of the test methods for automatic

fire detection devices in the U.S. reveals the fact

that different types and different sizes of fires

are used to evaluate different classes of detectors.

The result is a lack of comparison test data for

each detector class and, as a consequence, intelligent decisions can not be made in the selection of

automatic fire detectors for specific fire risks.

A new test method is proposed in which all automatic fire detectors, regardless of sensor type,

would be subjected to a series of the same test

fires. In addition, each test fire series would

consist of three different test fire sizes. From

the results obtained, it should then be possible

to match a detector's characteristics against a specific fire risk resulting in a more intelligent

application of automatic fire detectors.

Key words: Fire detector; test methods.

1
Each hostile fire produces a multitude of physical and

chemical characteristics. Some of these characteristics are

unique to the fire. Other characteristics are already

present in the environment and the fire only changes these

background characteristics, usually by augmenting them.

All of these fire-produced characteristics, or combinations

thereof, can be used to identify the presence of the hostile

fire. Some of these fire-produced characteristics give

stronger signals earlier in the fire growth than others.

As such, these signals are superior, as earlier, unambiguous

fire indicators.

There are in excess of a dozen different types of

automatic fire detection devices available to the fire

safety engineer. Some of these detectors sense physical

changes in the environment resulting from the fire. Other

detectors sense chemical changes in the environment. Table

No. 1 presents some, but not all, of the different types of

detection devices.

All automatic fire detectors possess one common attribute. Each is expected to detect a hostile fire early

enough to allow for effective counter measures, be it the

evacuation of threatened persons and/or the extinguishment

of the fire. But the different types of fire detectors do

not detect all types of fires with the same degree of rapid2
ity . This fact is fairly well known. What isn't well

known, however, is the magnitude of difference in response

of these different detectors to different fires. If, for

example, one were to describe several hypothetical fires in

a specific compartment and then ask at what point in the

fire growth each of the different detector types could be

expected to respond, it is quite likely that 9 out of 10

persons could not answer this question accurately.

Part of the reason for this is that the needed information is not readily available with which to answer questions

such as these. Yet, some of us are called upon from timeto-time to select a fire detector for a specific fire risk.

What do we do? Most likely, we listen to or read the claims

of competing manufacturers ’ and try to sort out the kernels

from the husks. If the number of telephone calls our office

receives is any indication, we are not too successful at

this sorting process.

A portion of the problem lies in the way we test and

approve automatic fire detection devices in the U.S. With

our present system, a completely different series of test

fires are used for each type of automatic fire detection

device. In addition, there is no grading of the fire sizes,

especially with regards to smoke detectors, so that the

tests are essentially "go - no go" tests. The results,

3
therefore, cannot be intelligently used to compare one

detector against another and, consequently, intelligent

utilization of the devices can not always be made. Wouldn't

it be nice if we had a test method which included one each

of all the representative types of fires a detector may

encounter and that these fires were graded in size so that

the discrimination level of each detector was readily apparent?

More on this in a moment but first I would like to review

the essentials in the testing of automatic fire detection

devices

The best test of an automatic fire detection device —

and it probably will always be so — is their use in practice

over many years under the most diverse conditions. This is,

of course, not always possible, particularly with more

recent products. One clearly cannot wait, sometimes for

several years, for the experience to accumulate as to the

advantages and limitations of the fire detection device.

At the present time, laboratory tests of automatic fire

detection devices are designed to provide yes/no decisions

on the premise that unsuitable detectors are determined and

eliminated by these laboratory tests. One then waits to see

whether those detectors which have passed the tests subsequently prove themselves in the field.

4
Undoubtedly, such laboratory tests coupled with field

experience are better than no tests. In the long run,

however, a different type of test for automatic fire detection

devices appears to be necessary. The aim of such a test

should be to determine and fully describe the behavior of

the automatic fire detection device. Here too, noncompliance

with certain minimum requirements would disqualify the

device. But in addition to establishing compliance with the

basic requirements, an attempt should also be made to establish the limits of the capabilities of the detector and the

conditions under which it can attain these limits. In so

doing, not only would the detector be passed as meeting the

basic requirements, but the results would give some indication as to the suitability, or unsuitability, of the detector

for specific fire risks.

The requirements and associated test methods can be

divided into two groups. In the first group, the influence

of adverse environmental effects, to which a detector may be

subjected, are investigated. We'll call this first group

the basic tests. In most cases the procedure is as follows.

The automatic fire detector to be tested is exposed to

a simulated, ever-increasing fire characteristic. The alarm

point of the detector is determined. Then the detector is

subjected to a series of environmental stresses such as high

5
humidity, dust, high temperature, corrosion, vibration, etc.

The alarm point is again measured, using the procedure described previously, to see whether and to what extent the

alarm point has changed.

Obviously, good repeatability of the simulated fire

characteristic and reliability of the measuring devices must

be obtained. Only in this way can one be sure that any

changes in the alarm point of the detector are due to changes

in the test specimen and not in changes in the simulated

fire characteristic or in changes in the measuring devices

themselves. There are some problems with our basic test

procedures, as presently conducted in the U.S., but they are

probably of less concern than the problems encountered in

the second group of tests.

This second group we'll call the trial test. In this

group of tests, several of the automatic fire detectors

under investigation are exposed to actual test fires, and

their behavior recorded. In principle, all automatic fire

detectors should be exposed to the same test fires. In this

way, comparisons can be made of the response characteristics

of the various fire detectors to differing fire types. As a

matter of fact, they are not. And herein lies the substance

of my talk. >

6
I want to introduce today a proposed new test method

for the evaluation of automatic fire detectors to real test

fires. This test method, while new to the U.S., has been in

use for about five years in West Germany. It has been

formulated and published as the test method for Germany [ 1

]

1

. Also, this test method has been adopted by the European

Insurance Association [2] as their standard for Europe. As

a consequence, it seems safe to presume that many of the

normal test anamolies have been eliminated from the test

method

The test method is composed of five types of fires.

These fires, which are shown in table No. 2, have been

selected to represent a broad spectrum of fire types. In

addition, the five test fires are divided into three sizes.

These three sizes have been selected to encompass the range

of sensitivities which can be expected from automatic fire

detection devices. Each fire is about twice the size of the

next smaller fire. Table Nos. 3 to 7 present a description

of the fuels as well as the three sizes used in each of the

five test fires.

The Class I fire, the smallest in each type of fire, is

representative of the smallest fire a detector can be expected

^Bracketed notations refer to references listed at the end

of this paper.

7
to respond to and still remain reasonably free from false

alarms, at least in most cases. The Class III fire, the

largest in each type of fire, is representative of the

largest fire that can be tolerated and still have sufficient

time to summon effective fire fighting assistance. Fires

which grow at a rate exceeding the Class III fire are probably not suitable for automatic fire detection. Other fire

safety means, such as automatic suppression, are called for

in situations such as these.

The geometry of the room in which these fire tests are

conducted is, as one would expect, crucial to the results

obtained in the tests. Figure 1 is an isometric view of one

suggested test structure. The test fires are located in the

center of the room. The detectors to be tested are placed

on the ceiling, 3 meters (10 feet) from the center of the

room. Measuring instruments, consisting of a smoke meter, a reference ionization chamber measuring device, and thermocouples, are also placed 3 meters (10 feet) from the center

of the room. A ceiling plan of the detector and measuring

instrument locations is shown in figure 2. The room should

be at a temperature of 21 + 3 °C (70 + 5 °F) and free of

smoke before each test. The specific dimensions chosen for

the test structure are those used by West Germany for their

test structure.

8
For tests of smoke detectors, test fires Nos. 1 through

5 would be conducted. Most of the presently available detectors which respond to smoke aerosols will not respond to

test fire No. 5, the clean-burning alcohol fire. As a consequence, test fire No. 5 could be deleted for tests of

generic classes of smoke detectors not responsive to cleanburning alcohol. This would include, for example, ionization

chamber smoke detectors and optical smoke detectors.

For heat detectors, test fires Nos. 1, 3 and 5 would be

conducted. Test fires Nos. 2 and 4 would not be conducted

as these test fires produce only slight changes in the

ambient temperatures at the detector location.

For other automatic fire detection devices, such as

flame detectors, combustible gas detectors, and cloud chambers,

for example, all five test fires would be conducted, at

least, until it became apparent which test fires would be

deleted from the test series due to lack of detector response

to these fires.

The procedure would be to start with the first fire

commencing in each case with the smallest fire or Class I

fire. If all of the detectors do not respond to Class I,

then the same fire is repeated at the Class II level. If in

Class II, one or more detectors do not respond, then the

9
same fire is repeated at the Class III level. Following

this, or as soon as all detectors have responded in either

Class I or Class II, then the procedure is repeated for the

next fire type.

A suitability table can then be prepared from the

results of the tests of the automatic fire detector. This

suitability table would show the response of the detector to

each of the test fires in one of the classification grades.

If all of the detector specimens tested responded to a Class

II fire size of one of the test fires, then a mark would be

placed in the appropriate column. If none of the detector

specimens, or less than all of the specimens, responded to a Class III fire, then no mark would be entered on the line

corresponding to this type of fire. Thus, a mark in any

column will indicate the smallest fire size to which all

detectors responded. No mark would indicate that one or more

of the detectors tested did not respond to the largest fire

size for a specific fire type. Table 8, taken from reference

[2], represents a typical response of an ionization chamber

smoke detector. Table 9, from reference [4], represents a typical response of a photoelectric smoke detector. Table

10, from reference [2], gives a typical response for a heat

detector while table 11, from reference [4] , gives the

typical response for a flame detector.

10
It should be reasonably obvious that the tabular presentation of the test results for a specific automatic fire

detector, as shown on these tables, yields useful information

with respect to the suitability or applicability of a given

detector for a specific fire risk. For instance, if the

most probable type of fire to be expected in an occupancy

can be forecast with reasonable accuracy, which is often

possible, then the type of detector offering the quickest

detection capabilities for that type of fire can be selected

from the results on the suitability table.

Another important feature of the test method I am

proposing here is that these tests can be performed in just

about any test facility without the need for large, expensive

testing facilities. Further, the proposed test method will

reduce all the many and varied test procedures we now have,

depending on the device to be tested, to a series of tests

having a large measure of commonality, a very desirable

objective, in my opinion.

Much work needs to be done before this proposed test

procedure for automatic fire detection devices will be ready

for consideration as a U.S. test standard. This is one of

the main objectives of the detection program at NBS and I

11
hope that others in the U.S. will take an earnest look at

this proposed test procedure, also.

It is likely that in time this same test method will be

proposed for international adoption through the International

Standards Organization (ISO) procedures. The test method

seems much superior to anything we have presently in the

U.S. As a consequence, it is my opinion that the faster we

can move towards adoption of this test method the better we

will be for it.

12
REFERENCES

[1] Richtlinien ftlr Automatische Brandmeldeanlagen

Anforderungen and Prtlf omethoden fur Punktformige Rauchand Warmemelder, (Guidelines for Automatic Fire

Detection Facilities: Requirements and Testing

Methods for Point Smoke and Heat Detectors) , Verband

der Sachversicherer e.V., Cologne (Nov. 1973).

[2] Test Methods for Point Smoke Detectors, Groupe de

Travail Incendie du Comite Europeen des Assurances,

Comite Technique Permanent, Paris (April 1974).

[3] Test Methods for Point Heat Detectors, Groupe de

Travail Incendie du Comite Europeen des Assurances,

Comite Technique Permanent, Paris (Nov. 1973).

[4] Schnell, M. , Points of View in Testing Flame

Detectors, Nat. Bur. Stand. (U.S.), NBSIR 76-1040

(May 197 6 ) .

13
Fig. 1. GEOMETRY OF DETECTOR TEST LABORATORY

Fig. 2. POSITION OF THE DETECTORS AND MEASURING

DEVICES ON CEILING OF DETECTOR TEST

LABORATORY

14
Table 1. Types of Automatic

Fire Detection Devices

HEAT SMOKE

Fixed Temperature

Rate-of-Rise

Combination of Above

Laser Beam

- Photoelectric

- Ion Chamber

- Extinction Beam

- Cloud Chamber

- Laser Beam

- Taguchi

- Fuel Cell

RADIATION

- Infrared

- Ultra Violet

- Combination of Above

15
Table 2. Proposed Standard Test Fires

Test Fire Type of Test Fire/Fuel Material

Test Fire No. 1 Flaming Cellulosic - Well-ventilated,

Wood Crib

Test Fire No. 2 Smoldering Cellulosic - Wood Strips on

a Hot Plate

Test Fire No. 3 Flaming Plastic - Flexible Polyurethane

Mats

Test Fire No. 4 Flammable Liquid with Pronounced Smoke

Production - Heating Oil or Kerosene

Test Fire No. 5 Flammable Liquid with Pronounced Heat

but Little Smoke - Methyl Alcohol

16
Table 3. Test Fire No. 1 - Flaming Cellulosic

Quantity of Fuel

Fuel Description Class I Class II Class III

Wood cribs - sticks

10 x 20 x 250 mm

(0.39 x 0.79 x 9.8 in)

0.75 kg

(1.65 lbs)

1.5 kg

(3.3 lbs)

3.0 kg

(6.6 lbs)

Base area of crib - mm 250x250 250x250 250x400

(in) (9. 8x9. 8) (9. 8x9. 8) (9.8x15.7)

Table 4. Test Fire No. 2 - Smoldering Cellulosic

Quantity of Fuel

Fuel Description Class I Class II Class III

Wood strips on hot plate

Strips, 10 x 20 x 50 mm,

(0.39 x 0.79 x 2.0 in).

No flame

3

Strips

6

Strips

12

Strips

Hot plate, 180 mm in

diameter (7 in), 1.3

kW power, surface

temperature - 400 to

450 °C (752 to 842 °F)

17
Table 5. Test Fire No. 3 - Flaming Plastic

Quantity of Fuel

Fuel Description Class I Class II Class III

Flexible polyurethane mats.

No inhibitors 12 3

Density - 20 kg/m 3 (1.25 Mats Mats Mats

lbs/ft 3

) Size - 20 x 400

x 500 mm (0.79 x 15.7 x 19.7 in) Mats laid on

aluminum foil with edges

folded up. Ignition by

5 g of methyl alcohol.

Table 6. Test Fire No. 4 - Flammable Liquid w/Smoke

Quantity of Fuel

Fuel Description Class I Class II Class III

Heating oil in square,

metal trays with 20 mm

(0.79 in) sides. Fuel

quantities -

15

(0.53

9

oz

)

25

( 0.88

g

oz

)

40 g

(1.4 oz)

Tray areas - 2 5 cm 2 (3.9 in 2

) 50 cm 2 (7.7 in 2

) 100 cm 2 (15.5 in 2

) Ignition by hot wire

or with 5 g of gasoline

18
Table 7. Test Fire No. 5 - Flammable Liquid w/Heat

Quantity of Fuel

Fuel Description Class I Class II Class III

Methyl alcohol in square,

metal trays w/50 mm

(2 in) sides. Fuel 1.2 kg 1.6 kg

quantities - (2.6 lbs) (3.5 lbs)

2.0 kg

(4.4 lbs)

Tray areas - 1100 cm2 (170 in 2

) 1500 cm2 (232 in 2

) 1900 cm 2 (294 in 2

)

19
Table 8. Fire Detector Classification Table —

Typical Results for: Ionization Smoke Detector

Type of Fire Classification

I II III

No. 1 - Flaming Cellulosic X

No. 2 - Smoldering Cellulosic X

No. 3 - Flaming Plastic X

No. 4 - Flammable Liquid (Fuel Oil) X

No. 5 - Flammable Liquid (Alcohol)

From: Reference [2]

20
Table 9. Fire Detector Classification — Typical Results

for: Photoelectric Smoke Detector

Type of Fire Classification

I II III

No. 1 - Flaming Cellulosic X

No. 2 - Smoldering Cellulosic X

NO. 3 - Flaming Plastic X

NO. 4 - Flammable Liquid (Fuel Oil) X

No. 5 - Flammable Liquid (Alcohol)

From: Reference [4]

21
Table 10. Fire Detector Classification — Typical Results

for: Heat Detector

Type of Fire Classification

I II III

No. 1 - Flaming Cellulosic X

No. 2 - Smoldering Cellulosic

No. 3 - Flaming Plastic X

No. 4 - Flammable Liquid (Fuel Oil)

No. 5 - Flammable Liquid (Alcohol) X

From: Reference [3]

22
Table 11. Fire Detector Classification — Typical Results for

Infrared Flame Detector

Type of Fire Classification

I II III

No. 1 - Flaming Cellulosic

No. 2 - Smoldering Cellulosic

NO. 3 - Flaming Plastic X

No. 4 - Flammable Liquid (Fuel Oil) X

No. 5 - Flammable Liquid (Alcohol) X

From: Reference [4]

23
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBSIR 76-11722. Gov’t Accession

No.

3. Recipient’s Accession No.

4. TITLE AND SUBTITLE

A NEW TEST METHOD FOR AUTOMATIC FIRE DETECTION

DEVICES

5. Publication Date December 1976

6. Performing Organization Code

7. AUTHOR(S)

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/Task/Work Unit No. 4928677

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 Report

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

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

bibliography or literature survey, mention it here.)

An analysis of the test methods for automatic fire detection

devices in the U.S. reveals the fact that different types and

different sizes of fires are used to evaluate different classes

of detectors. The result is a lack of comparison test data for

each detector class and, as a consequence, intelligent decisions

can not be made in the selection of automatic fire detectors for

specific fire risks. A new test method is proposed in which all

automatic fire detectors, regardless of sensor type, would be

subjected to a series of the same test fires. In addition, each

test fire series would consist of three different test fire sizes.

From the results obtained, it should then be possible to match a detector's characteristics against a specific fire risk resulting

in a more intelligent application of automatic fire detectors.

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 detector; test methods.

18. AVAILABILITY [X; Unlimited

F°r Official Distribution. Do Not Release to NTIS

\_

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(XT] Order From National Technical Information Service (NTIS)

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