It

NBSIR 75-673

Development of a Fire Test Method

for Flexible Connectors in Air

Distribution Systems

Lionel A, Issen

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

April 1975

Final

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBSIR 75-673

DEVELOPMENT OF A FIRE TEST METHOD

FOR FLEXIBLE CONNECTORS IN AIR

DISTRIBUTION SYSTEMS

Lionel A. Issen

Center for Fire Research

Institute for Applied Technology

National Bureau of Standards

Washington, D.C. 20234

April 1975

Final

U. S. DEPARTMENT OF COMMERCE. Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts. Director
s
SI Conversion Units

In view of present accepted practice in this technological area, U. S.

customary units of measurement have been used throughout this report. It

should be noted that the U. S. is a signatory to the General Conference on Weights and Measures which gave official status to the metric SI system of

SI units in 1960. Readers interested in making use of the coherent system

of SI units will find conversion factors in ASTM Standard Metric Practice

Guide, ASTM Designation E 380-72 (available from American Society for Testing

and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103). Coversion factors for units used in this paper are:

Length

1 in = 0.0254* metre

1 ft ' 0.3048* metre

Area

2 -4 2 1 in = 6.4516* x 10 metre

1 ft^ = 9.2903 X lO"^ metre^

Force

1 lb (Ibf) = 4.448 newton

1 kip = 4448 newton

Pressure, Stress

1 psi = 6895 pascal

1 psf = 47.88 pascal

Energy

1 ft-lbf = 1.3558 joule

Moment

1 Ibf-ft = 1.3558 newton-metre

Temperature

°C = 5/9 (Temperature °F - 32)

ii
I
CONTENTS

Page

1. INTRODUCTION 1

2. CONSTRUCTION AND INSTRUMENTATION 2 2.1. General 2 2.2. Furnace Closure 2 2.3. Branch Duets 3

2.4. Flexible Connectors 3

2.5. Instrumentation 9

3. TEST RESULTS 9

3.1. Furnace Temperatures 9

3.2. Assembly Temperatures and Performance 9

3.2.1. Enclosure Outlet Air Temperatures 22

3.3. Smoke Measurements 22

3.4. Closure 22

4. SUMMARY 22

APPENDIX A. A PROPOSED METHOD OF TEST FOR FIRE RESISTANCE OF

FLEXIBLE CONNECTORS FOR HEATING VENTILATING AND AIR CONDITIONING

SYSTEMS 24

Al. Scope 24

A2. Significance 25

A3. Test Procedure 25

A3.1. Fire Exposure 25

A3. 2. Locations of Theraocouples on the Specimen .... 25

A4. Construction Details 25

A4.1. Method of Attachment 26

A4.2. Firestop at Penetrations 26

A4.3. Furnace Closure 26

A5. Report of Results 26

A6. Criteria for Evaluation 27

APPENDIX B. REFERENCES 27

iii

DEVELOPMENT OF A FIRE TEST METHOD FOR FLEXIBLE

CONNECTORS IN AIR DISTRIBUTION SYSTEMS

Lionel A. Issen

The report describes fire tests on four flexible con- nectors of the type used in air conditioning systems. Four

flexible connectors (aluminum, felted glass fiber, steel,

and woven glass fiber) were exposed to a standard ASTM E-119

fire test. The results were in agreement with previous re- sults in which a different sized branch duct was used in the

assemblies. The results indicated a need to control furnace

pressures. The test results were used to develop a proposed

test method for fire testing flexible connectors. This proposed test method is described in the report.

Key words: Aluminum; ducts; fire tests; flexible connectors;

furnace pressures; glass fiber; heat ventilating and air

conditioning systems; high-rise buildings; steel; terminal

units

1. INTRODUCTION

At present there is very little information on the effects of fire

on ducts, dampers, connectors and other components of heating ventilating and air conditioning (HVAC) systems, and on the influence of fire

and smoke spread within HVAC systems.

In the current construction of high-rise buildings, the ducts and

connectors are usually not protected by fire rated ceilings; that is,

they are behind an ornamental, non-rated, drop ceiling. Such a ceiling

will fail quickly exposing the flexible connectors to direct fire

exposure. The flexible connector which connects a branch duct to a terminal unit can fail by separation from the branch duct, by failure of

the blocking around the connector where it penetrates a fire barrier, or by melting or pyrolysis of the connector material. Any failure of the

flexible connector could allow smoke, flame, hot and noxious gases to

enter the HVAC system and the connected modules.

The need for a test method for flexible connectors became apparent

after the One New York Plaza fire in August 1970 in which failure of

flexible connectors was considered partly responsible for the spread of

fire and smoke [1]^. A task group of the National Fire Protection

Association (NFPA) dealing with revisions to their specifications governing

Numbers in brackets correspond with the literature references listed

in Appendix B.

1
air conditioning and ventilating systems [2] requested the aid of the

National Bureau of Standards in developing a test method for evaluating

the fire resistance of flexible connectors. These tests and the proposed

test method which is described in the appendix of this paper are in

response to this request.

The NFPA Task Group agreed that a major measure of satisfactory

fire performance for a flexible connector assembly would be the ability

to prevent a fire breaking into the HVAC system and the adjoining

occupancy module for one hour under standard fire endurance conditions.

Such a performance requirement would probably eliminate from use the

more hazardous materials that might be used for flexible connectors.

Other requirements could include a limitation on siioke and toxic gas

generation by the flexible connector assembly.

The proposed flexible connector test method, which is given in the

appendix, is a step in the direction of testing and evaluating the fire

resistance of a portion of a HVAC system consisting of a duct, connector

and terminal unit assembly. This test differed from previous tests in

the following manner: 1) a smaller size branch duct was used, 2) an improved furnace closure and deck was used, and 3) an attempt was made to

take smoke density measurements. This report supplements the previously

reported tests [3].

> . , r ^ -V 2. CONSTRUCTION AND INSTRUMENTATION

2.1. General

In the test setup four independent flexible connector assemblies

were set in the National Bureau of Standards floor furnace. The assemblies consisted of a branch duct inside the furnace, a terminal unit

with an architectural enclosure outside of the furnace, and a flexible

connector between the branch duct and the terminal unit which were

separated by the furnace closure.

. . , 2.2. Furnace Closure

As in the previous tests, a raised closure was used to provide

clearance above the furnace burners for the branch ducts and flexible

connectors [3]. In this test an improved floor/ceiling construction was

used to close in the top of the furnace.

The closure consisted of 10-inch open-web steel joist framing, with

two layers of 5/8-inch type X gypsum board, screw attached to the bottom

chords, and on top of which rested gypsum planks. The steel joists

rested on a 24-lnch high stud wall protected with gypsum board and

sprayed vermlculite plaster over expanded metal lath. One side of each

joist was covered with 5/8-inch type X gypsum board. This was to prevent flames which might break through, at a flexible connector penetra2
tion, from affecting an adjacent assembly. The space between the joists

was left open to observe the behavior of that portion of the flexible

connectors that was Immediately outside of the furnace, and to allow

the opening In the furnace closure to be closed-off If a flexible

connector melted or pyrollzed. The details of the closure are shown In

figure 1.

2.3. Branch Ducts

In these tests a smaller branch duct (18" x 18" x 6') was used as compared with previous tests (24" x 24" x 10' and 18" diameter x 10').

This was done in order to see if a smaller branch duct would provide

similar information, as this would be easier to set up, and could be set

up in a smaller furnace than the 14' x 18' (nominal) National Bureau of

Standards facility. The branch ducts had closed ends and as in previous

tests there was no air circulation through them because it is assumed

that the ventilation fans in an HVAC system will be shut down when a fire occurs

2.4. Flexible Connectors

Four types of flexible connectors were tested simultaneously:

aluminum, steel, felted glass fiber, and woven glass fiber. The felted

glass fiber connector was 5 inches in diameter^ and the others were all

6 inches in diameter.

The layout of the four independent duct/connector/terminal unit

assemblies within the furnace is shown in figure 2. Construction details

are shown in figures 3 and 4. Each end of the flexible connector was

open.

The connectors were attached to the duct with a flange plate and

friction band, in accordance with the manufacturer's instructions for

the type of connector used. Previous tests [3] indicated that the

attachment was sturdy and able to withstand the fire exposure for the

desired period. This attachment was used here because the test was intended to provide information for the proposed test method and it was desirable to have an attachment that would last for at least one hour.

The flexible connectors were left bare in this test, unlike earlier

tests [3] in which the connectors were wrapped with glass fiber insulation.

The penetration through the furnace closure was faced with a steel

flange plate and the annular space between the flexible connector and

the furnace closure was blocked with mineral wool packing (see fig. 5).

The plate was attached to the gypsum board with screws.

At the time of the test is was not possible to get a felted glass fiber

connector 6 inches in diameter because of an industry strike.

3

5
6
7
1

i;
Simulated terminal units and architectural enclosures, similar to

those used in previous tests were placed on the deck. The dimensions of

these items are shown in figure 4. The terminal unit did not contain

any heating/cooling unit as it was felt that a finned pipe insert would

only marginally affect any air movements.

2.5. Instrumentation

Each assembly was instrumented with an optical density device and

thermocouples. The optical density device was located at the outlet

grill of the architectural enclosure. The thermocouples were located at

points where it was desirable to monitor the temperatures of the assembly.

Each assembly was instrumented with 15 thermocouples distributed as follows: two in the branch duct, six on the flexible connector between

the branch duct and the simulated terminal unit, one at the middle of

the inlet on the terminal unit, two at the outlet of the terminal unit,

two on the inlet of the architectural enclosure, and two on the outlet

of the architectural enclosure. The thermocouples were all fabricated

from 24 gage diameter type K chromel-alumel wire. The locations of the

thermocouples are shown in figure 6.

3. TEST RESULTS

3.1. Furnace Temperatures

During the test the furnace temperatures closely followed the

values prescribed in the standard [4] (see fig. 7).

3.2. Assembly Temperatures and Performance

The temperatures within each assembly are summarized on two figures.

The first figure of each set shows the temperatures from the duct to the

terminal unit, the second shows the temperature in the terminal unit and

architectural enclosure. This data is shown on consecutive pairs of figures

for each flexible connector assembly in figures 8 to 15. A comparison of

the outlet temperatures on the architectural enclosures is shown in figure 16.

The aluminum connector melted at about 7 minutes and the opening at

the closure was sealed with a noncombustible board to permit the con- tinuation of the one-hour test. This is shown in figures 8 and 9 where

the thermocouples that were located above the closure showed a rapid

decrease in temperature after 8 minutes.

The performance of the felted glass fiber and of the woven glass

fiber connectors were closely similar in this test: both fell into the

furnace at 20 minutes. The difference in behavior compared to test 516

[3] was that the woven glass fiber connector was bare in this test and

9
10
300_

2Q0_

100_

- STflNDflRO El 19

0 ^0

FIGURE 7 TEST 532 FURNfiCE TEMPERRTURE

20 30 40

TIME - MINUTES

11
DUCT TEMPERATURES T/C

CONNECTOR TEMPERRTURE

TEMPERATURE

TEMPERATURE

TEMPERATURE

TEMPERATURE

CONNECTOR

CONNECTOR

CONNECTOR

CONNECTOR

14.15

AT DUCT T/C 1 ,2

AT CLOSURE T/C 3

ABOVE CLOSURE T/C

AT DECKING T/C 5

AT TERMINAL UNIT T/C

FIGURE 8

^

40

TIME - MINUTES

TEST 532 TEMPERATURES ALONG ALUMINUM CONNECTOR BETWEEN

DUCT AND TERMINAL UNIT

12
1500

O DUCT TEHPERRTURE T/C 14.15

A INLET fllR TEMPERATURE TERMINRL UNIT T/C 7

14Q0_ -I- OUTLET HIR TEflPERRTURE TERMINRL UNIT T/C 8,9

X OUTLET RIR TEMPERRTURE ARCH I TECTURRL ENCLOSURE T/C 12.13 ^ INLET RIR TEMPERRTURE RRCH I TECTURRL ENCLOSURE T/C 10.11

f> 161 DEG C LINE ( 139 RBOVE RM8IENT J

1200_

1 1Q0_

1G00_

TIME - MINUTES

FIGURE 9. TEST 532 RLUMINUM RSSEMBLY TEMPERRTURES RLONG TERMINRL UNIT AND

RRCHI TECTURRL ENCLOSURE

13
DUCT TEMPERATURE T/C 14,15

CONNECTOR TEMPERATURE AT DUCT T/C 1.2

CONNECTOR TEMPERATURE RT CLOSURE T/C 3

CONNECTOR TEMPERATURE ABOVE CLOSURE T/C 4

CONNECTOR TEMPERATURE AT DECKING T/C 5

CONNECTOR TEMPERATURE AT TERMINAL UNIT T/C 6

1200_

1100_

1000_

TIME - MINUTES

FIGURE 10 TEST 532 TEMPERATURES ALONG FELTED GLASS FIBER CONNECTOR

BETWEEN DUCT AND TERMINAL UNIT

1500-.

1400_ +

X

1300_

14
1500_

14Q0_

1300_

O DUCT TEMPERRTURE T/C 14

A INLET flIR TEMPERRTURE

-I- OUTLET RIR TEMPERRTURE

X OUTLET RIR TEMPERRTURE

<!> INLET RIR TEMPERRTURE

15

TERMINRL UNIT

TERMINRL UNIT

RRCHITECTURRL

RRCHITECTURRL ^ 161 DEG C LINE ( 139 RBQVE RMBIENT

T/C 7 T/C 8,9

ENCLOSURE

ENCLOSURE

T/C

T/C 10,11

1200_

1100_

1000-

TIME - MINUTES

FIGURE II TEST 532 FELTED GLRSS FIBER RSSEMBLY TEMPERRTURES RLONG TERMINRL

UNIT RND RRCHITECTURRL ENCLOSURE

15
1500

1400_

1300_

1200»

1 100_

1000.

900_

100_

O DUCT TEMPERRTURE T/C 14.15

A CONNECTOR TEMPERRTURE RT DUCT T/C 1 .2

+ CONNECTOR TEMPERATURE RT CLOSURE T/C 3

X CONNECTOR TEMPERATURE RBOVE CLOSURE T/C 4

<& CONNECTOR TEMPERRTURE RT DECKING T/C 5

4- CONNECTOR TEMPERRTURE RT TERMINRL UNIT T/C 6

MELTING OF CONNECTOR

INSIDE FURNACE

So 40

TIME - MINUTES

FIGURE 12 TEST 532 TEMPERRTURES RLONG WOVEN GLASS FIBER CONNECTOR

BETWEEN DUCT AND TERMINAL UNIT

16
15Q0_

1400.

1300_

DUCT TEMPERATURE T/C 14

INLET RIR TEMPERATURE

OUTLET RIR TEMPERATURE

OUTLET RIR TEMPERATURE

INLET AIR TEMPERATURE

15

TERMINAL UNIT T/C 7 TERMINAL UNIT T/C 8,9

RRCHITECTURAL ENCLOSURE

ARCHITECTURAL ENCLOSURE

T/C

T/C

12.13

10,11

'^ 161 DEG C LINE [ 139 ABOVE AMBIENT ]

"5o^ 40

TIME - MINUTES

FIGURE 13 TEST 532 WOVEN GLASS FIBER ASSEMBLY TEMPERATURES ALONG TERMINRL

UNIT AND ARCHITECTURAL ENCLOSURE

17
150Q-,

14QQ.

1300.

1200_

1 100.

1000_

O DUCT TEMPERRTURE T/C U.IS

4x CONNECTOR TEMPERRTURE RT DUCT T/C 1 ,2

+ CONNECTOR TEMPERRTURE RT CLOSURE T/C 3

X CONNECTOR TEMPERRTURE RBOVE CLOSURE T/C 4

<^ CONNECTOR TEMPERRTURE RT DECKING T/C 5 ^ CONNECTOR TEMPERRTURE RT TERMINRL UNIT T/C 6

10 ¥o fo 40

TIME - MINUTES

FIGURE 14 TEST 532 TEMPERRTURES RLQNO STEEL CONNECTOR BETWEEN

DUCT AND TERMINAL UNIT

18
1500_

1 400.

1300.

O DUCT TEMPERRTURE T/C 14

A INLET RIR TEMPERATURE

+ OUTLET flIR TEMPERRTURE

X OUTLET RIR TEMPERRTURE

<3> INLET RIR TEMPERATURE

15

TERMINRL UNIT

TERMINAL UNIT

RRCHITECTURRL

RRCHI TECTURAL

T/C 7

T/C 8,9

ENCLQSURE

ENCLOSURE

T/C

T/C

12

10

13

1 1 4- 161 DEG C LINE ( 139 ABOVE AMBIENT )

1200_

1 100_

1000_

900

o

° 800

ZD»—

CE

orUJQ_

SI

700

6Q0_

500

400_

300_

200_

100

10 ¥o 40

TIME - MINUTES

5^

FIGURE TEST 532 STEEL ASSEMBLY TEMPERATURES ALONG TERMINAL UNIT AND

RRCHITECTURRL ENCLOSURE

19
500 _

O ALUMINUM

475_ A FELTED OLflSS FIBER

+ WOVEN GLASS FABRIC

X GfiLVflNIZED STEEL

450_

425_

400_

375„

350_

0 So So fo Eo "70

, - rtr V ; TIME - MINUTES

FIGURE 16 C0MPflRISON QF OUTLET flIR TEMPERATURES QN ARCHITECTURAL ENCLOSURES

20
it was covered with 1-lnch glass fiber Insulation In the earlier test.

In this test the penetration at the felted glass fiber connector was manually closed off at 47 minutes as the connector was glowing red above

the furnace closure. The woven glass fiber was not closed off as this

connector maintained some structural Integrity outside the furnace after

the portion Inside the furnace had melted. During the test the temperature of both glass fiber assemblies varied from what would be expected

from the changes In the furnace temperatures. Referring to figures 10

and 11 for the felted glass fiber connector assembly: the connector and

air temperatures rose rapidly for the first 4 minutes or so of test,

then fell until 20 minutes of test, then rose again rapidly reaching a maximum at 30 minutes of test, and then (with the exception of the

connector temperature above the closure) rose gradually or remained more

or less constant until the penetration through the closure was closed at

47 minutes. Referring to figures 12 and 13 for the woven glass fiber

connector assembly: the connector and air temperatures rose gradually

until 20 minutes of test, the temperature then rose rapidly during the

next 3 to 8 minutes all reaching more or less a maximum by about 20

minutes, after this time the air temperatures remained more or less

constant while the connector temperatures dropped a little and then

also remained constant until the end of the test. The explanation for

this is that during the test the flow of hot gases from the furnace

through the assemblies varied in quantity and direction. When the flow

was from the furnace outwards, the air temperatures at the terminal unit

rose; when it was zero or from the room into the furnace, the temperatures

fell. Thus, unless furnace pressures are controlled, the test may not be

repeatable.

In a real world fire situation, the pressure of the hot gases from

the fire would be positive, that is, greater than the ambient pressures.

Thus, in order to have performance that reflects the expected levels of

pressure in a fire situation, the furnace should be run under slight

positive pressure. The data also suggest that the flow conditions

between the flexible connector assembly and the furnace are marginally

stable, that is, changes in local conditions, such as failure of a flexible connector assembly, can result in changes in the direction of

flow. This may also be true for actual installations where there may be an induced air flow in a HVAC system even when the blower is not operating.

Though the level of pressure to be run in a test is difficult to

establish, certain qualitative and quantitative parameters can be used

to establish limits on the range of pressure. With the currently

available test furnace, if too high a pressure is used, the test room

will be filled with smoke and gases from the test. Another factor is

the range of pressures that a fire can produce: analysis and test

results [5,6] indicate that the positive pressure to be expected from a fire can range from a maximum of about 0.1 inches water with many values

being less than about .05 inches water and ranging do\>m to zero.

Though in a real fire situation the positive pressures that can be

developed vary over a range of values, a rating test probably needs to

21
consider only a more limited range of pressures. A justification for

this viewpoint can be drawn from the operation of ASTM E-119 where test

and analytic data indicate that many actual fires differ in intensity

and duration from that applied by ASTM E-119 [7]. For these reasons it

Is proposed at this time that the furnace be run at a positive pressure

of .01 + .003 inches of water.

The steel connector maintained its Integrity for the 60 minutes of

test. That is, at the end of the test the attachment to the branch duct was intact and the blocking at the penetration of the furnace closure

was intact.

'

• 3.2.1. Enclosure Outlet Air Temp<^ratures

In figure 16 the outlet temperatures of the four architectural

enclosures are compared. The outlet temperature of the galvanized steel

assembly is below the allowable temperature rise of 139°C (250°?) which

is usually taken to represent the temperature rise limit.

' 3.3. Smoke Measurements

An attempt was made to take optical density measurements of smoke

at the outlet of the flexible connector. The experimental arrangement

used did not work properly because of a defect in the setup and no usable smoke data were obtained.

^ ' " ^'

• " 3.4. Closure

In this test an elaborate furnace closure was used. This closure

made it easier to set up the test, to make observations on the top of

the deck in the space between the closure and the deck. This closure

had no significant affect on the test results as compared with previous

tests [3].

-; '^--^ - '

' ^n-'., .^n SUMMARY

A test to develop information from a proposed method for testing

flexible connectors was run at NBS on March 5, 1974. The test was arranged to test a range of connectors (aluminum, steel, felted glass

fiber and woven glass fiber) simultaneously.

The results indicated that the fire performance of a connector, the

method of attaching a connector to its branch duct and the integrity of

the penetration through the fire barrier can be evaluated.

The criterion of specifying a limit on the outlet air temperatures

at the architectural enclosure is similar to the maximum unexposed surface temperature criterion for the fire resistance of floors [4]. Since

22
the outlet air temperature appears to be dependent on the furnace pressure, a requirement for furnace pressures is included in the proposed

test method.

Although no furnace pressure measurements were made, in order to

simulate fire conditions and to improve uniformity in testing, the

furnace should be run under a positive pressure.

Further tests should be run to improve the method for taking smoke

measurements.

As in other areas of fire endurance evaluations, consideration

should be given to using supplementary laboratory tests such as smoke

generation, potential heat, flame spread, and ease of ignition to

evaluate other fire performance properties of the assembly and its

components

23
APPENDIX A

A PROPOSED METHOD OF TEST FOR FIRE RESISTANCE OF FLEXIBLE

CONNECTORS FOR HEATING VENTILATING AND AIR CONDITIONING SYSTEMS

Al. Scope

This method evaluates the fire performance of a flexible connector

system in terms of: a) resistance of the flexible connectors to failure

by direct fire penetration, b) adequacy of attachment method of the

flexible connector to the duct, c) effectiveness of the blocking (firestopping) of the penetration through a fire-rated floor and ceiling, and

d) visual observations of smoke density at the outl(it of an architechural

enclosure. This test is applicable to flexible connectors made in whole

or in part of metal, plastic, ceramic or other material. The test

provides a measure of the performance of a flexible connector system in

a prescribed arrangement during the fire exposure period only, and does

not imply suitability for use after test. The results are applicable to

other constructions only when similar methods of attaching the flexible

connector to its branch duct and when similar blocking or firestopping are used

The terminal unit is not included for evaluation in this proposed

test procedure. Instead, a standard simulated terminal unit and architectural enclosure are used so that the performance of a flexible

connector is evaluated independent of a specific type of terminal unit.

Note; The test arrangement is based on experiments that were made

at the National Bureau of Standards in 1972, and which are described in

reference [3] and in the accompanying paper. The test arrangement Is the same as that shown In figures 1, 3, 4 and 6 of the preceding report.

These tests, which were based on the fire performance of an assembly under

exposure conditions of the standard fire resistance test [4], indicated

that the proposed test arrangement will provide a measure of the pertinent

factors. Correlation of the performance of flexible connectors and systems

in other configurations is not intended or implied.

A test result is expressed in terms of the time period to failure

as indicated by one or more of the following events: a) melting or pyrolysis of the flexible connector, b) partial or complete separation

of the flexible connector from its duct, c) passage of hot gases,

flame, or smoke through the blocking at the penetration through the

furnace closure^ and, or d) the temperature at the discharge opening of

the top of the architechural enclosure rising 250°F (139°C) above the

initial temperature at the beginning of the test.

^By visual observation and the temperatures of thermocouple 4 (see figure 6)

24
A2. Significance

Pipes, shafts, ducts and flexible connectors often pierce major fire

barriers in buildings and the integrity of these items may be critical in

terms of the spread or containment of the fire. This test provides a means of comparing and evaluating the fire performance of a flexible

connector system when exposed to the direct effects of a prescribed

severe fire. A single test is used to evaluate the flexible connector,

the attachment of the flexible connector to its duct, and the method of

firestopping (backpacking) the penetration through a fire barrier of a flexible connector."

A3. Test Procedure

A3.1. Fire Exposure

The fire exposure is the same as that described in ASTM E-119 [2].

The furnace pressure at the connector level should be maintained at .01 + .003 inches of water.

A3. 2. Locations of Thermocouples on the Specimen

A minimum of 15 thermocouples are placed in or on components of the

assembly. The thermocouples are placed at the following locations: two on the outside of the flexible connector at its junctions with the duct, one on the flexible connector on the fire-side of the furnace closure,

one on the flexible connector on the room side of the furnace closure,

one at the junction of the flexible connector and the terminal unit, one

in the air inlet stream of the terminal unit at the junction with the

flexible connector, two in the outlet air stream of the terminal unit,

two in the inlet air stream of the architectural enclosure, and two in

the outlet air stream of the architectural enclosure.

The passage of flames directly through the flexible connector or through an opening at the junction of the connector and duct will be

shown by a rapid rise in air temperature at the outlet to the architectural

enclosure

A4. Construction Details

The test specimen consists of a length of flexible connector one

end of which is connected to a simulated duct inside the furnace, and

the other end which is connected to a simulated terminal unit outside the

furnace. The length of the shortest side, or the diameter of the

simulated duct, should be at least 18 inches. The length of the simulated duct should be at least 6 feet, and the ends are to be closed.

There is no specified length for the flexible connector, but the length

25
Inside the furnace should be at least six diameters and not less than 2 feet 6 inches. Any bends should either conform to the recommendations

of the manufacturer of the flexible connector or to specifications of the

approval authority for whom the test is being run. Only one flexible con- nector may be attached to any one simulated duct and terminal unit assembly,

but more than one assembly may be tested at the same time by utilizing separate installations in the furnace. The ends of the flexible connector

are to be open to permit flow between the branch duct and the architectural

enclosure

A4.1. Method of Attachment

The method of attaching the flexible connectoi' to the simulated duct

must be clearly described and shown on the drawings and in the report for

the test. The method of attaching the flexible connector should be either

as specified by the manufacturer or should be representative of local field

methods depending on the requirements of the local code authority.

A4.2. Firestop at Penetrations

The method of blocking and firestopping the penetrations of the

flexible connector through the furnace closure must be clearly described

and shown on the drawings and in the report for the test.

' A4.3. Furnace Closure

The furnace closure may be framed by precast concrete joists or steel

joists. The joists shall be protected by a furnace closure that remains

intact and dimensionally stable for at least 1-1/2 hours. (A type of

closure that meets this requirement consists of two layers of 5/8-inch

type X gypsum board protected by one layer of vermiculite or perlite plaster

on expanded metal lath attached with bugle head type screws spaced at not over 12 inches on center at right angles to tuning channels at not over 24

inches on center). The joists may be covered with a concrete plank, or gypsum plank, or gypsum board cover. The spaces between the top and bottom

of the joists should be left open so that the condition of that portion of

the flexible connectors, that is outside of the furnace, can be observed

during the test

'

' A5. Rtport of Rtsults

The report should include the following information: a) assembly

drawings showing pertinent dimensions, b) details of method of attaching

flexible connector to simulated duct, c) details of method of blocking

penetration through furnace closure, d) locations of thermocouples and

details of method or attaching assembly, e) temperatures measured during

test at least every 5 minutes, f) visual observations of the smoke emitted

26
by the assembly, (The time when there are significant changes in the quantity and density of the emitted smoke should be noted. Observations should

be made at least every 10 minutes) , g) observations of the condition of the

assembly and of significant events during the test including the time that

the flexible connector separates from the simulated branch duct, the time

that fire breaks into the flexible connector, and visual changes in the

amount and character of any smoke emitted at the discharge of the architectural enclosure, and h) any other pertinent information including photographs that will assist in evaluating the fire resistance of the flexible

connector

A6. Criteria for Evaluation

The criteria for evaluation are:

1. For the rating period all parts of the assembly wall

shall remain fastened, without gaps or openings developing.

If any part of the assembly (attachment, blocking, joints,

materials) fails before the end of the rating period, it

shall be cause for rejection.

2. The outlet air temperature at the architectural enclosure

shall not rise more than 139°C (212°F) during the rating

period.

APPENDIX B. REFERENCES

[1] Powers, W. Robert, Report of Fire at One New York Plaza, New York,

New York, The New York Board of Fire Underwriters, Bureau of Fire

Prevention and Public Relations, New York, N. Y. (1970).

[2] Installation of Air Conditioning and Ventilation Systems, NFPA 90A,

National Fire Protection Association, Boston, Massachusetts.

[3] Issen, Lionel A. , Report of Fire Tests on Flexible Connectors in

HVAC Systems, Nat. Bur. Stand. (U.S.), NBSIR 73-267 (July 1973),

NTIS Order No. COM-73-11955 ; $3.50.

[4] Standard Methods of Fire Tests of Building Constructions and

Materials, ASTM Designation E119-73, American Society for Testing

and Materials, Philadelphia, Pennsylvania (1973).

[5] Rockett, John A., Fire Induced Gas Flow in An Enclosure (to be

published)

[6] Fung, Francis C. W. , Evaluation of a Pressurized Stairwell Smoke

Control System For A 12 Story Apartment Building, Final Report,

Nat. Bur. Stand. (U.S.), NBSIR 73-277 (June 1973), NTIS No. PB225278; $3.50.

27
[7] Pettersson, Ove, Structural Fire Engineering Research Today and

Tomorrow, Bulletin 1, Lund Institute of Technology, Lund,

Sweden (1966).

USCOMMNBS-DC

28
NBS-114A (REV. 7-73)

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OK KI-PORT NO. NBSIR 75-673

2, Gov't Aci'cssion No.

3. Rccipic-ni's Acce.'^sion No.

4. TITLE AND SUBTITL1-; Development of a Fire Test Method for Flexible

Connectors in Air Distribution Systems

5. Publication Date April ly75

6. Performing Organization ( odo

7. AUTHOR(S)

Lionel A. Issen

8. Performing Organ. Report No.

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Prou < r / Task/Work Unit No. ty^DD /

1 1 . C'ontr.K 1 / Gra.nt N:i

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. ABSTRAC'T (A 200-word or less factual summary of most si^ificant information. If document includes a significant

bibliography or literature survey, mention it here.) The report describes fire tests on four flexible connectors of the

type used in air conditioning systems. Four flexible connectors (aluminum,

felted glass fiber, steel, and woven glass fiber) were exposed to a standard

ASTM E-119 fire test. The results were in agreement with previous results

in which a different sized branch duct was used in the assemblies. The

results indicated a need to control furnace pressures. The test results were used to develop a proposed test method for fire testing flexible

connectors. This proposed test method is described in the report.

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) Aluminum; ducts ; fire tests ; flexible connectors; furnace

pressures; glass fiber; heat ventilating and air conditioning systems; high-rise

buildings; optical density; steel; terminal units.

18. AVAILABILITY Unlimited

I

' For Official Distrib ution. Do Not Release to NTIS

I

' Order From Sup. of Doc, U.S. Government Printing Office '

. Washington, D.C. 20402, SD Cat. No. CH " XX Order From National Technical Information Service (NTIS)

Sprmgfield, Virginia 22151

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(THIS REPORT)

UNCL ASSIFIED

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