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NBSIR 81-2444

Smoke Movement Through A

Suspended Ceiling System

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

Issued:

February 1 982

Final Report

Funded in part by:

Veterans Administration

Office of Construction Research

shington, DC 20420

apartment of Health and Human Services

ashington, DC 20201

national

of STANTIBUS

UBBABT

NBSIR 81-2444 MAY 14 1982

SMOKE MOVEMENT THROUGH A

SUSPENDED CEILING SYSTEM

John H. Klote

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

Issued:

February 1 982

Final Report

Funded in part by:

Veterans Administration

Office of Construction Research

Washington, DC 20420

Department of Health and Human Services

Washington, DC 20201

U S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director
' “ ^ t lAHOS' 'a

*' »'• * Hf( !,: >8% H YA
TABLE OF CONTENTS

Page

LIST OF FIGURES v

LIST OF TABLES vii

i Abstract . 1

1. INTRODUCTION 2

2. TEST FACILITY 3

3. EXPERIMENTAL DETAILS 5

3.1 Instrumentation 5 3.1.1 Temperature ..... 5 3.1.2 Smoke Obscuration . 5 3.1.3 Carbon Monoxide ..... 5 3.1.4 Velocity 6

3.2 Test Program 6

3.3 Test Procedures 6

3.3.1 Smoke Candle Test 6

3.3.2 Smoldering Tests 7 3.3.3 Low Energy Tests 7 3.3.4 High Energy Tests 8

3.4 Mattresses and Bedding 8

3.4.1 Low Energy Tests 8

3.4.2 High Energy Tests 9

4. HAZARD ANALYSIS 9

4.1 Smoke Obscuration 10

4.2 Carbon Monoxide 10

5. TEST RESULTS AND DISCUSSION 11

5.1 Smoke Candle Test 11

5.2 Smoldering Tests 12

5.2.1 Tests 1 and 2 12

5.2.2 Test 3 13

5.3 Low Energy Tests 14

5.3.1 Tests 4 and 5 14

5.3.2 Test 6 15

5.3.3 Test 7 16

5.3.4 Test 8 16

5.3.5 Test 9 17

5.3.6 Test 10 18

iii
TABLE OF CONTENTS (cont'd)

Page

5.4 High Energy Tests 19

5.4.1 Tests 11 and 12 19

5.4.2 Smoke Leakage into Room 2 20

5.4.3 Smoke Movement through the Ceiling 21

5.5 Comparison of Test Types 22

5.5.1 Smoke Movement 22

5.5.2 Hazardous Conditions 22

5.5.3 Smoke Detection 23

5.6 Interstitial Space Exhaust .... 24

5.7 Patient Room Exhaust 26

5.8 Smoke Movement Paths 27

6. SUMMARY AND CONCLUSIONS 28

7. ACKNOWLEDGEMENTS 30

8. REFERENCES 31

iv
LIST OF FIGURES

Page

Figure 1. Floor plan of test facility 33

Figure 2. Section of test facility 34

Figure 3. Ceiling plan of test facility 35

Figure 4. Ventilation system for test facility 36

Figure 5. Instrumentation plan for test facility . . 37

Figure 6. Instrumentation plan for interstitial space 38

Figure 7. Instrumentation in burn room doorway 39

Figure 8. Instrumentation in burn room 40

Figure 9. Instrumentation in room 1 41

Figure 10. Floor plan for test facility showing status of

doors and windows during the tests 42

Figure 11. Smoke obscuration for the smoke candle test 43

Figure 12. Smoke obscuration in the burn room and the

interstitial space for tests 1 and 2 44

Figure 13. Smoke obscuration in the burn room and the

interstitial space for tests 2 and 3 45

Figure 14. Upper gas temperatures for tests 4 through 1 ... . 46

Figure 15. Upper gas temperatures for tests 8 through 10 ... . 47

Figure 16. Smoke obscuration for tests 4 and 5 48

Figure 17. Smoke obscuration for test 5 49

Figure 18. Carbon monoxide concentrations for test 5 50

Figure 19. Smoke obscuration for test 6 51

Figure 20. Smoke obscuration for test 7 52

Figure 21. Carbon monoxide concentrations for tests 6 and 7 . . 53

Figure 22. Smoke obscuration for test 8 54

v
LIST OF FIGURES (cont'd)

Page

Figure 23. Smoke obscuration for test 9 55

Figure 24. Smoke obscuration for test 10 56

Figure 25. Temperatures for test 11 57

Figure 26. Temperatures for test 12 58

Figure 27. Smoke obscuration for tests 11 and 12 59

Figure 28. Carbon monoxide concentrations for tests 11 and 12 . . 60

Figure 29. Pressure difference across burn room ceiling for

tests 10, 11 and 12 . 61

Figure 30. Smoke obscuration for the smoke candle test and

test 1 62

vi
LIST OF TABLES

Page

Table 1. Fan Schedule 63

Table 2. List of Instrumentation 64

Table 3. Test Schedule 66

Table 4 . Ignition Source 67

Table 5. Technical Data for Mattress and Bedding for

Tests 4-10 68

Table 6. Technical Data for Mattress and Bedding for

Tests 11 and 12 69

Table 7. Times to Hazard Level Due to CO Concentrations 70

Table 8. Smoke Detector Activation Times 71

vii

SMOKE MOVEMENT THROUGH A SUSPENDED CEILING SYSTEM

John H. Klote

Abstract

A series of full-scale tests were conducted to

evaluate smoke movement through a suspended ceiling

and into an interstitial space of a hospital type

facility. A test facility specifically constructed

for this project is described. The test series

consisted of one smoke candle test and 12 fire tests

including both smoldering and flaming fires. Smoke

movement through the suspended ceiling system was

evaluated in terms of the total smoke movement

through the test facility. The effects of ventilation and smoke exhaust on smoke concentration in

the test facility were investigated. It was con- cluded that the use of the interstitial space

exhaust as described in this paper will effectively prevent hazard conditions due to smoke

downflow through suspended ceilings. It was also

concluded that smoldering fires of the type

examined in this test series are not a significant

problem in hospitals.

Key words: Ceiling systems; hazard analysis;

hospitals; interstitial space; mattresses; smoke

control; smoke exhaust; smoke movement; ventilation

systems
1 . INTRODUCTION

Smoke is commonly recognized as a major killer in building fires.

One of the reasons for this is that smoke flows through numerous leakage paths to locations remote from the fire, resulting in a hazard to

human life. These leakage paths can be open doors, cracks around

closed doors, stairwells, elevator shafts, construction cracks in

walls and floors, and even cracks or openings in a suspended acoustical

ceiling.

Extensive use of suspended acoustical ceilings has resulted in

questions within the Veterans Administration (VA) and among the fire

protection community regarding the potential of danger resulting from

smoke leakage through the ceiling. This is especially true for cases where there are large areas above the suspended ceiling, such that

smoke could travel through these paths to locations remote from the

fire. Such smoke movement could involve smoke movement up through the

ceiling, horizontal flow in the space above the ceiling, and then

downward flow into an occupied space.

This paper reports the results of a test series conducted to

evaluate smoke movement through a suspended ceiling system. Particular

emphasis in this study was directed toward examining this problem under

a construction arrangement typical of a hospital. A test facility was constructed which consisted of four patient rooms and a section of

corridor. Above these spaces there was an open space referred to as the interstitial space. The interstitial space was separated from the

lower spaces by a suspended ceiling system. In hospitals the interstitial space is typically used for mechanical and electrical equipment,

ductwork, piping, and conduit.

Smoke is defined for this paper to consist of all airborne products of

combustion including both particles and gases.

2
In this test series the extent of smoke penetration through the

ceiling was evaluated from (1) smoke candles, (2) smoldering fires, (3)

low energy flaming fires, and (4) high energy flaming fires. Smoke

concentrations were determined by measuring smoke obscuration and CO

concentration. Smoke concentrations were recorded in a number of

locations throughout the test facility in order to evaluate smoke

movement through the ceiling system in light of smoke movement throughout the rest of the test facility. The effects of the ventilation,

occupancy space exhaust, and interstitial space smoke exhaust on smoke

concentration in the test facility were also investigated. In addition,

a hazard analysis, limited to smoke obscuration and CO concentration,

is included.

2. TEST FACILITY

The test facility was built inside another structure to minimize

the effect of the wind. This facility has four patient rooms and a section of corridor as shown in figure 1. The burn room has one door

to the corridor and another smaller door to the space outside the test

facility. This smaller door was included to provide a convenient exit.

This door was closed throughout all the tests except for the first 5 to

10 seconds of each test when the person who ignited the test fire was

exiting. Reference in this report to the "burn room door" will mean

the door between the burn room and the corridor.

The doors throughout the test facility had polymer seals on both

sides and the top. These seals were a commercial product which was specifically made for use on metal door frames. The sealing mechanism

was a thin polymer leaf against which the door closed. Small leakage

paths existed at the corners where these seals met. The doors were

undercut 23 mm (7/8 in). No attempt was made to seal these cracks at

the bottom of the doors from the four rooms into the corridor. However,

bottom sweeps were installed on the two doors to the outside of the

test facility.

3
Figure 2 shows a section through the test facility. The walls of

the facility consist of 16 ran (5/8 in) type X gypsum board on steel

studs. All of the gypsum board joints were taped and spackled. The

perimeter walls of the test facility have gypsum board on the interior

side only. The interior walls are 2.44 m (8 ft) high and have gypsum

board on both sides. The suspended ceilings are separately hung in

each room.

The ceiling was constructed of 0.61 x 1.22 m (24 x 48 in) acoustical

tiles supported by a steel grid system. The ceiling plan is shown in

figure 3. The construction of the ceiling was (see figure 2) in accor2 dance with the ceiling portion of UL listing A202 [1] , floor ceiling

assembly, with the exception that ceiling hold down clips were left off one ceiling tile in each room and one tile in the corridor. These

uncliped tiles were used as access panels. In addition, an open cell

polymer seal was installed between the ceiling wall molding and the

wall, as is common practice in Veterans Administration hospitals. The

ceiling tiles weighed 49.6 N/m2 (1.00 lb/ft2 ).

The ventilation system for the test facility is shown in figure 4.

This system consists of supply and exhaust for the four patient rooms

as well as ventilation for the interstitial space. Table 1 is a schedule of the ventilation fans. The system was designed and balanced

to provide six air changes per hour in the patient rooms. Four radial

fans were installed for ventilation of the interstitial space. These

fans are capable of being repositioned in the ductwork so that they can be used for either supply or exhaust of the interstitial space. Each

radial fan has a damper for adjusting air flow. During this test

series the only radial fan used was fan 5 in the exhaust mode. All of

the outside air dampers were motorized.

Numbers in brackets refer to references listed at the end of this

paper

4
3. 3.1EXPERIMENTAL DETAILS

Instrumentation

The instruments used in this test series are shown in figures 5 thru 9 and are listed in table 2. Response times of smoke detectors

and a tell-tale sprinkler were recorded automatically by activation of

a relay which stopped a clock. All tests were recorded with 35 mm

still camera or on video tape with separate coverage in the burn room

and in the interstitial space. Generally, all instrumentation channels

were recorded at 20 second intervals for the smoldering tests and at

13 second intervals for the flaming tests. The data acquisition system

was located in an instrumentation trailer adjacent to the main building.

3.1.1

Temperature

Temperatures in the test facility were measured at locations shown

in figures 5 thru 9, and outside air temperature was measured. These

temperatures were measured by bare beaded chromel-alumel thermocouples

made from 0.51 mm (24 gauge) diameter wire.

3.1.2

Smoke Obscuration

The obscuration of smoke was measured at 12 locations as shown in

figures 5 thru 9. The smoke meters measured optical density over a 1.0 m (3.28 ft) horizontal path using spotlights as light sources and

using photodiodes (PIN 3DP) as receivers.

3.1.3

Carbon Monoxide

Carbon monoxide (CO) was continuously measured at five locations

as shown in figures 5 thru 9. In rooms 1, 2, and 3 the CO sample

probes were located at approximately head height for a patient laying

in bed. In the burn room the CO sample probe was located approximately

5
0.91 m (3 ft) above the bed. This location was chosen so that it would

collect smoke from the fire plume. Another CO probe was located at

approximately the mid-height of the interstitial space. CO concentrations were measured with nondispersive, infrared analyzers.

3.1.4 Velocity

Air and gas velocity were measured in the burn room doorway and

the window in room 2. In both cases the velocity was measured 0.1 m

(4 in) below the top and 0.1 m (4 in) above the bottom of the opening.

The room 1 window was open only for tests 1 thru 3 and accordingly the

velocity at this window was recorded for these tests only. Velocities

were measured with bidirectional probes [2] connected to variable

reluctance differential pressure transducers.

3.2 Test Program

The smoke leakage performance of the ceiling system was tested

with smoke generated by four types of sources: (1) smoke candle, (2)

smoldering fire, (3) low energy flaming fire, and (4) high energy

flaming fire. Throughout the tests the doors to rooms 1 and 3 were

open and the door to room 2 was closed. The status of doors and windows

for all the tests is shown in figure 10. The test schedule for all of

the tests except the smoke candle test is listed in table 3.

3.3 Test Procedures

3.3.1 Smoke Candle Test

A commercially available three minute duration smoke candle was

set in the center of the flat steel surface of the hospital bed and

ignited. Visual observations were made and the test was recorded on video tape. This test was performed so that smoke movement from smoke

candles could be compared with smoke movement from real fires.

6
3.3.2 Smoldering Tests

A smoldering fire of high reproducibility was developed for these

tests. The pallet for the smoldering fires was constructed in the

following steps:

a. Fiberglass insulation 0.58 mm (23 in) wide and 89 mm (3.5

in) thick was placed over a plywood board 1.83 m x 0.58 m x

13 mm (72 in x 23 in x 1/2 in) thick.

b. Three layers of untreated cotton batting 0.69 m (27 in) wide

and 25 mm (1 in) thick were placed on top of the fiberglass.

c. A bedspread of 50 percent polyester and 50 percent cotton was placed on top.

d. The assembly was then turned over, compressed with approximately

70 N (16 lb) force and the spread was pulled tight and stapled

securely on both sides.

The pallet was placed with the plywood side down on the hospital

bed in the burn room. Three slits were made in the pallet, approximately

76 mm (3 in) long and 40 mm (1.6 in) deep into the cotton batting. One

of these slits was located in the center of the pallet and the other

two were located 0.61 m (24 in) from each end and equidistant from the

sides. The pallet was ignited by placing a lighted half cigarette in

each slit and then pushing the slit shut. The cotton batting had been

stored in a room at 30 percent RH and 21° C (70° F)

3.3.3 Low Energy Tests

These tests are referred to as low energy tests because the

mattress was filled with fire retardant treated cotton padding. A

detailed description of the mattress and bedding for these tests is

provided in section 3.4.1. The fire was started in a steel wastebasket

7
containing 20 sheets of newspaper of which ten crumpled and ten were

rolled and placed vertically. The wastebasket was placed in contact

with the blanket and top sheet. Each test began when the contents of

the wastebasket were ignited with a cigarette lighter. All bedding and

wastepaper were kept in a storage room where the humidity was in the

range of 30 - 50 percent RH and the temperature was in the range of

16 - 23° C (60 - 74° F)

3.3.4 High Energy Tests

These tests were referred to as high energy tests because the

mattress was filled with polyurethane foam. A detailed description of

the mattress and bedding for these tests is provided in section 3.4.2.

The mattress was one which has been used as part of the NBS mattress

flammability test program [3, 4, 5], A polyethylene wastebasket filled

with 443 g (.97 lb) of combustibles was placed next to the bed as was done in the NBS mattress tests. Table 4 lists the contents of the

wastebasket. The wastebasket was placed in contact with the bedspread.

Each test began when the contents of the wastebasket were ignited with

a cigarette lighter. All bedding and wastebasket items were kept in a 50 percent RH conditioning room at a temperature of 21° C (70° F) for

at least 24 hours prior to each test in order to be consistent with the

prior NBS mattress tests [3],

3.4 Mattresses and Bedding

3.4.1 Low Energy Tests

The mattresses and bedding for the low energy flaming tests were

supplied by the Veterans Administration. The mattress was an innerspring mattress constructed of fire retardant treated cotton felt

padding with a retardant treated vinyl impregnated nylon tick covering

(outermost layer). The bedding consisted of a blanket, two sheets, a pillow and a pillow case. The pillow had cotton ticking and was filled

with duck feathers. A detailed description of the mattress and bedding

is provided in table 5. For test 4, the first low energy flaming test,

8
a fire retardant blanket of a matrix fiber of 50 percent vinyl and 50

percent vinyon was used. In this test only the newspaper in the

wastebasket and a small amount of the cotton sheet burned. Because the

fire intensity was so low, it was decided to use a cotton blanket

furnished by the Veterans Administration for subsequent low energy

tests

3.4.2 High Energy Tests

The mattress and bedding for the high energy tests were the same

as the mattress and its bedding materials used in the NBS mattress test

program [3]. The mattress chosen was a polyurethane innerspring one which was coded M-02 in the mattress tests. The bedding was obtained

from a commerical hospital supplier and was intended for use in health

care facilities. The bedding consisted of a cotton drawsheet, two

sheets, and a bedspread, a pillow case and pillow filled with shreaded

polyurethane foam. A detailed description of the mattress and bedding

is listed in table 6.

4. HAZARD ANALYSIS

The primary objective of this project was to study smoke movement

through the interstitial space resulting from a fire originating below

the space in an occupied room. In addition, a limited discussion

regarding the resultant hazard to human life from such fires is also

presented. For this paper the hazard analysis was limited to smoke

obscuration and CO concentration. It should not be inferred that CO is

the only toxic gas that is significant in fire situations. This was

the only gas measured due to the limited scope of the project. In this

discussion of hazard analysis, temperature was not considered because

the primary concern of this study is with the hazards associated with

smoke at locations where there is negligible temperature rise due to

the fire.

9
4.1 Smoke Obscuration

The limiting level of smoke obscuration for human safety was selected for two separate hazards in this fire test scenario. The

first concerned rescue of a patient from a patient room, and the second

involved the use of the corridor as an exit way. Obscuration was measured at a number of locations (section 3.1.2) in order to study

smoke movement. For hazard analysis only the smoke meters located 1.5

m (5 ft) above the floor in the patient rooms and in the corridor were

considered. Critical levels of obscuration selected for each location

were based on investigations by Jin [6, 7]. Jin recommended limits on obscuration based on not reducing the walking speed below that of a blindfolded subject in a smoke free environment. This obscuration was

approximately 0.25 OD/m. Accordingly, in this paper, the value of 0.25

OD/m is used as the critical level of smoke obscuration for both the

patient rooms and the corridor.

4.2 Carbon Monoxide

CO forms carboxyhemoglobin (COHb) in the blood and thereby reduces

the oxygen carrying capacity of the blood. Therefore, percent COHb is a meaningful measure of CO toxicity. The following approximate procedure, adopted for this test program to evaluate COHb, has been

employed by O’Neill and Hayes [4, 5],

Steward derived an equation of COHb from experiments with human

volunteers [8], The volunteers were subjected to very high concentrations

of CO and their COHb levels were then measured. CO uptake is directly

proportional to the breathing rate which is approximately 6.5 £/min

for an individual at rest. The breathing rate increases with activity

and also from exposure to CO2

. A 4 percent concentration of CO2 will

more than double the breathing rate [9]. Since both of these factors

must be considered in a fire situation, a breathing rate of 18 2,/min was selected for purposes of analysis. The equation developed based

on Steward's work for determining C0Hb% is:

10
ACOHb% = 5.98 x 1CT4 (At) [CO] 1,036

where At is time in minutes and CO is concentration in ppm. An initial

value of 0.75 percent COHb was established, based on information provided by Alarie and Zullo [10] for use in the computation. A 25 percent

calculated COHb was selected in this study as the critical level of

COHb at which incipient incapacitation may occur [11].

In addition to the threshold for time-rated accumulation, another

limit must be selected for CO exposure. Instantaneous doses of high

levels of CO must also be considered due to the physiological effects

such as cardiac arrhythmia [12] which can occur independently of the

effects of increased COHb. Claudy [13] reported on the effects of

exposure to high concentrations of CO. The results of his work indicate

that incipient incapacitation may occur with only a few short breaths

at an exposure level of 10,000 ppm CO. And, at a slightly higher

concentration of 12,800 ppm Claudy reported that unconsciousness could

occur in 2 to 3 breaths, followed by death in 1-3 minutes. Based on

this an instantaneous threshold of 10,000 ppm (1.0 percent by Vol) CO was selected as a criterion, in addition to the time integrated exposure

resulting in COHb level of 25 percent.

5. TEST RESULTS AND DISCUSSION

5.1 Smoke Candle Test

The smoke candle test was conducted under the following conditions

1. The burn room door was closed.

2. The window to room 1 was open.

3. The supply and exhaust systems for the four patient rooms were operating.

4. The interstitial space exhaust fans were off.

5. The status of the other doors and the windows was the same as for all of the other tests, as listed in table 3.

11
As expected, visual observation revealed that the smoke filled the

burn room quickly, but there was a much lower level of smoke in the

other rooms, the corridor and the interstitial space. Figure 11 indicates

that the optical density in the corridor and the interstitial space was considerably lower than the optical density in the burn room. In

addition, it was observed that the major path of smoke movement through

the suspended ceiling was at joints between the walls and the metal wall

molding of the suspension system, in spite of the fact that these joints

were filled with open cell foam. In section 5.5, this smoke candle test

is compared with the other tests conducted in this series.

5.2 Smoldering Tests

In the first three tests, the burn room door was closed and smoldering

fires were set as described in section 3.3.1. The test conditions for

these tests are summarized in table 3. Throughout all three tests there

was only slight visible smoke in the corridor and rooms 1, 2, and 3.

Visual observation after 60 minutes revealed that small quantities of

smoke were flowing under the burn room door into the corridor. The CO

concentrations outside the burn room were negligible. In all three

tests the temperature outside the burn room remained constant, and the

temperature 0.1 m (4 in) below the burn room ceiling only increased by

8° C.

5.2.1 Tests 1 and 2

Test 1 was conducted with the supply air and exhaust air on and all

the ceiling tiles in place. In order to determine the effect of missing

ceiling tiles, test 2 was conducted with two ceiling tiles missing from

the burn room ceiling. Figure. 12 shows smoke obscuration in the burn

room and interstitial space for these two tests. The data from test 1

is for less than 60 minutes because of a failure in the data acquisition

software. As expected the obscuration is greater in the interstitial

space in test 2 with the ceiling tiles missing from the burn room.

12
5.2.2 Test 3

In order to determine the effect of the ventilation system on smoke

movement, test 3 was a repeat of test 2 except that the supply and

exhaust fans to the four patient rooms were shut off. Figure 13 shows

the smoke obscuration in the burn room and the interstitial space for

tests 2 and 3 showing. There is a substantial increase in smoke con- centration when the ventilation system is off.

The window in room 1 was open throughout these tests to determine

the effect of an open window on smoke movement. In all three smoldering

tests there was flow into room 1 at the bottom of the window and out of

room 1 at the top. The air velocities at the window fluctuated in the

range of 0 to 0.5 m/s (0 to 0.15 ft/s). This type of flow is indicative

of natural air currents which exist in buildings, and would be unusual

for a window open to the outside. In such cases the flow is usually

dominated by either wind or stack effect or by both. Accordingly, the

flow would be in one direction across the opening. Because the burn

room door was closed, the open window in room 1 probably had no significant effect on the smoldering fire. However, for tests with the burn

room door open, the open window would probably have an affect on the

fire. This would impair reproducibility of the tests and yield no benefits. For this reason the window in room 1 was closed for all

further tests.

During the smoldering tests the smoke obscuration and CO

concentrations did not result in a significant threat to life. CO

levels in the burn room were below 0.15 percent for all three tests, and

COHb levels for a person in the burn room were well below the critical

level. Smoke obscuration was below critical level throughout tests 1 and 2. And, in test 3 smoke obscuration remained below the critical

level for the first 30 minutes of the test.

13
A worry with a smoldering fire is that it will continue until

hazardous conditions result, or until the fire develops into a flaming

fire. While there was only the slightest visible smoke in the corridor

and in rooms 1, 2 and 3, a very irritating smell was present in these

spaces after the first few minutes of each test. It is apparent from

figures 12 and 13 that smoke obscuration due to the smoldering fires is

below the hazard level for at least a half hour. Hospitals have people

who are awake 24 hours a day who can smell these fires and then easily

extinguish them. Therefore, smoldering fires of the type examined in

this test series do not appear to represent a serious problem in hospitals.

5.3 Low Energy Tests

In tests 4 through 10, fire retardant cotton mattress and bedding

as described in section 3.4.1 were burned. The test conditions for

these tests are summarized in table 3. The burn room door was open for

all tests, with the exception of test 7. The window in room 1 was closed for all tests for reasons discussed in section 5.2.2. The status

of all windows and doors for these tests is provided in figure 10.

Figures 14 and 15 show the upper gas temperatures in the burn room for

these tests.

5.3.1 Tests 4 and 5

Test 4 was conducted with both the supply air and the exhaust air

on. For this test a fire retardant blanket was used on the bed. This

blanket was very successful in limiting the growth of the fire as can be

seen from the upper gas temperature in figure 14. Test 5 was the same

as test 4 except that a cotton blanket was used to increase the fire

intensity. This was successful and cotton blankets were used for the

rest of the low energy tests. Figure 16 shows smoke obscuration in the

corridor and in the interstitial space for both test 4 and 5. It is

apparent that the smoke obscuration is much greater in test 5 when the

cotton blanket was on the bed.

14
During test 5 the burn room and rooms 1 and 3 were open to the

corridor. It was visually observed that these spaces filled with smoke

after about 2 or 3 minutes. This is also apparent from the smoke obscuration data shown in figure 17. As would be expected the corridor was obscured slightly before rooms 1 and 3. The door to room 2 was closed

throughout the test series, and smoke was observed flowing under the

door and into room 2. It can be seen from figure 17 that the smoke

obscuration in room 2 was considerably lower than that of the corridor

or other rooms. Figure 17 shows that the obscuration of the interstitial space during test 5 was much lower than that of the corridor or that of rooms 1 and 3. This indicates that the smoke flow through the

open doorway was much greater than that through the ceiling system.

During this test there was no indication of smoke movement from the

interstitial space to room 2.

Similar observations regarding smoke movement can be obtained by

examining CO concentration. Figure 18 shows CO concentrations for test

5. The CO concentrations in the burn room, and rooms 1 and 3 were

relatively high, while the concentrations in room 2 and the interstitial

space are negligible. It can be observed from figure 18 that the burn

room concentration of CO is about twice that measured in rooms 1 and 3.

This is because the burn room CO probe samples the gas from the fire

plume

5.3.2 Test 6

The test conditions for test 6 were the same as those for test 5

except that the supply air and the return air were shut off. This test was conducted to determine the extent to which smoke obscuration would

increase without ventilation. Figure 19 shows smoke obscurations for

test 6. As in test 5 the optical density in the corridor and rooms 1

and 3 increased rapidly while the optical density in the interstitial

space and room 2 was much lower. As in test 5 it is apparent that the

smoke flow through the open doorway was much greater than the upward

smoke flow through the ceiling system. There were no indications of

smoke flowing from the interstitial space into room 2.

15
In comparing smoke obscuration from tests 5 and 6 (figures 17 and

19) , it is apparent that the increase in smoke obscuration is dramatic

when the ventilation is shut off. This is especially so for room 2 where the optical density was five times greater when the ventilation

was off.

5.3.3 Test 7

Test 7 was conducted to determine the effect of a closed burn room

door on smoke concentration. This test was the same as test 6 except

for the closed door. Figure 20 shows smoke obscurations for test 7. By

comparing figures 19 and 20 it is apparent that closing the burn room

door significantly reduces the smoke obscuration in the corridor and in rooms 1, 2, and 3. However, these figures also show that closing the

burn room door has essentially no effect on smoke obscuration in the

interstitial space. This is probably because the major path of smoke

movement into the interstitial space is through the burn room ceiling in

either case. In addition, there were no indications of smoke flowing

from the interstitial space into room 2.

Figure 21 shows CO concentration in the burn room and in room 1 for

tests 6 and 7. This data shows that closing the burn room door results

in increased CO in the burn room and decreased CO in room 1. The burn

room CO concentration is increased to the extent that in test 7 the

critical level of COHb is reached in 22.6 minutes. However, in all the

other low energy tests where the burn room door was open the critical

level was not reached.

5.3.4 Test 8

Test 8 was performed to determine the effect of exhausting two air

changes per hour from the interstitial space. With the exception of

exhausting the interstitial space, the conditions of this test were the same as those of test 6. It was expected that exhausting the interstitial space would act to pull smoke through the ceiling and into the

16
interstitial space. Accordingly, the level of smoke in the corridor and

patient rooms would decrease. Figure 22 shows smoke obscuration for

test 8. In comparing the results of tests 6 and 8 (figures 19 and 22),

it is apparent that exhausting the interstitial space did indeed result

in reduced smoke obscuration in the corridor and in rooms 1, 2, and 3.

Unfortunately, this reduction in obscuration did not result in greatly

reduced hazard conditions. It can also be noticed by comparing figures

19 and 22, that exhausting the interstitial space had little effect on the smoke obscuration in the interstitial space. In this test, as in

earlier tests, smoke was observed leaking into room 2 through the crack

under the door. It should be noted that there were no indications of

smoke flowing from the interstitial space into room 2.

5.3.5 Test 9

In order to determine the leakage paths into room 2 and to reconfirm

the results of test 8, test 9 was conducted. Test 9 was the same as test 8 except that the cracks around the door to room 2 were sealed with

tape. Figure 23 shows smoke obscuration for test 9. In comparing the

smoke obscuration for tests 8 and 9 (figures 22 and 23), it is apparent

that there was good repeatability between the two tests everywhere

except in room 2. As expected, the two figures show that the smoke

obscuration in room 2 was lower with the cracks around the door taped.

It was observed during test 9 that smoke was flowing into room 2 through

the exhaust grill. The exhaust and supply systems were off, and apparently smoke traveled from the burn room to room 2 through the exhaust

duct.

As in test 8, the interstitial space exhaust had little effect on the smoke obscuration in the interstitial space, and there was no indication of smoke movement from the interstitial space into room 2.

17
5.3.6 Test 10

Test 10 was conducted to determine the effect of operating the

exhaust system for the patient rooms during a low energy fire. The door

to room 2 was still sealed, and during the test no visible smoke was observed in room 2. This can be seen from the smoke obscuration data

for test 10 which is provided in figure 24. The reasons for the absence

of smoke in room 2 during this test are discussed in detail in section

5.7.

Test 10 is the same as test 6 except that the exhaust air system is on in test 10. Comparison of the smoke obscuration for tests 5 and 10

(figures 19 and 24) shows that the obscuration throughout the facility

was considerably lower when the exhaust air was on. This result was anticipated because test 10 is very similar to test 5 (figure 17) where

both the exhaust and supply were operating. However, the smoke obscuration from test 10 was lower than that for test 5, indicating that exhaust

alone does more to eliminate smoke than exhaust and supply together.

An explanation which might be proposed for this is that the supply

system provides combustion air which increases the combustion rate.

This explanation does not consider that when the supply fan is off there

is an inflow of outside air through whatever small cracks exist in the

test facility. This inflow equals the exhaust rate and would also

provide combustion air to the fire.

In addition, smoke feedback into the supply air system did not

occur because the supply air was completely taken from the outside on

the opposite side of the building from where the exhaust air was rejected

(figure 4) . Another possible effect is that the supply air reduced the

ability of the exhaust system to remove smoke from the patient rooms. The supply diffusers were located approximately in the middle of each

patient room (figure 3) and the return air grills were located 6 ft

18
above the floor in each patient room (figures 1 and 4). Because of the

proximity of the diffusers and exhaust grill it is likely that the

supply air diluted the smoke flowing into the exhaust system. This

would reduce the smoke exhaust capability of the exhaust system.

5.4 High Energy Tests

5.4.1 Tests 11 and 12

In tests 11 and 12, polyurethane mattress and bedding as described

in section 3.3.4 were burned. The test conditions for these tests are listed in table 3. The burn room door was open for both of these tests.

The status of all doors and windows in the test facility is provided in

figure 10. Figures 25 and 26 show temperatures for tests 11 and 12.

These figures indicate that these tests were highly repeatable.

Test 11 was conducted with all the ventilation fans shut off. For

tests 11 and 12, the door to room 2 was sealed to determine the extent

of smoke movement through the duct work. Under these circumstances the

smoke movement into room 2 would be similar to that into a room which

had solid partitions separating it from the fire space. In test 11 as

in test 9 smoke was observed flowing into the room 2 through the exhaust

duct.

Test 12 was conducted with the air exhausted from the interstitial

space at a rate of 2 air changes per hour. The exhaust grill and the

supply register in room 2 were sealed off to determine other possible

paths of smoke into room 2

During both tests 11 and 12 visual observation revealed that shortly

after ignition there was considerable smoke flow out of the top of the

burn room door, and that after about 2 minutes the corridor, and rooms 1

and 3 were obscured with smoke. In addition, during the first 4 minute

of tests 11 and 12, smoke was observed flowing into the interstitial

space through the cracks between the wall molding and the wall. And, at

about 4 minutes the interstitial space filled very rapidly with smoke.

19
Figure 27 shows smoke obscuration for tests 11 and 12. This confirms

the visual observations, described above. Similar trends can be found

by observing the CO concentrations shown in figure 28. After about 4

minutes the CO concentration in room 1 increased rapidly, while the CO

concentrations in the interstitial space increased at a somewhat lower

rate

It is also apparent from figure 28 that the CO concentrations in

room 1 were lower in test 12 when the interstitial space was exhausted.

This is similar to the reduced smoke concentrations caused by interstitial exhaust during the low energy fires of tests 8 and 9. It can be

observed from both figures 27 and 28 that exhausting the interstitial

space has little effect on the smoke concentrations in the interstitial

space

5.4.2 Smoke Leakage into Room 2

The effect of sealing the return grill and the supply diffusers in

room 2 should reduce the smoke concentrations in that room by preventing

smoke movement through the duct systems. This behavior can be observed

by examining smoke obscuration in figure 27 or by examining CO concentration in figure 28. Smoke obscuration and calculated COHb in room 2 were both well below the critical levels selected for this study. The

concentration of CO in room 2 was below the instantaneous threshold.

However, if the fire had been of longer duration it is possible that the

smoke obscuration and COHb might have exceeded critical levels in room

2 .

During test 12 smoke may have infiltrated room 2 through the

suspended ceiling, through cracks around the door frame, through cracks

between the partitions, etc. Upon examination before and after test 12,

traces of smoke movement were evident on the ceiling tile around the

diffusers in room 2. Visual examination of these smoke traces could not

conclusively determine the direction of this smoke movement. It should

be pointed out that in a real hospital the interstitial space would be

20
many times larger, and therefore the smoke in the interstitial space

would be more diluted. This indicates that any smoke flow down through

a ceiling system would probably result in smoke concentrations even lower than those in room 2 during test 12.

5.4.3 Smoke Movement through the Ceiling

The discussion of tests 11 and 12 in section 5.4.1 included a description of the smoke concentrations in the interstitial space.

During the first 4 minutes of these tests, smoke was observed flowing

from the burn room into the interstitial space through the cracks between

the ceiling wall molding and the wall. Apparently, the open cell foam

(section 2) used to seal these cracks was ineffective in stopping smoke

movement. At approximately 4 minutes into the test, it was observed

that the smoke in the interstitial space increased very rapidly. This

rapid increase in smoke concentration in the interstitial space can be

observed from the CO concentrations shown in figure 28 and from smoke

obscuration in figure 27.

After test 11 the ceiling of the burn room was still intact.

However, the metal suspension system was warped which resulted in a large number of cracks which would let smoke flow into the interstitial

space. It can be observed from figure 25 that the gas temperature 0.1 m

(4 in) below the burn room ceiling was very high; it peaked at 725° C

(1340° F) at about 6 minutes into the test. It seems apparent that the

high temperature of the combustion gases near the ceiling warped the

suspension system and that a greatly increased flow of smoke through the

ceiling system resulted. This accounts for the rapid increase in smoke

in the interstitial space at about 5 minutes into the test. After test

11 the burn room ceiling was rebuilt for test 12.

Figure 29 shows the pressure difference across the burn room ceiling (see instrument number 56 on figure 8) . For this figure a positive pressure indicates that the burn room is at a higher pressure

than the interstitial space. It can be observed from figure 29 that in

21
both tests 11 and 12 the pressure increased to about 9 Pa (0.036 inch

H2 O) at about 5 minutes into the test. Then the pressure suddenly

dropped to below 1 Pa (0.004 inch H2 O). This drop in pressure coincides

with the rapid increase in smoke concentration in the interstitial

space. When the suspension system warped, the increased leakage area resulted in both increased gas flow into the interstitial space and

decreased pressure differential across the ceiling. It can also be

observed from figure 29 that the differential pressures across the

ceiling were larger for test 12. This was due to the presence of interstitial exhaust during test 12.

5.5 Comparison of Test Types

5.5.1 Smoke Movement

It is well known that the movement of smoke produced by smoke

candles is significantly different than the movement of smoke produced

by flaming fires. This is because the smoke from smoke candles lacks

the buoyant forces which exist in smoke produced by flaming fires.

However, one might think that smoke movement due to smoke candles and

smoldering fires would be very similar because in both cases the buoyant

forces of the smoke are negligible. A comparison of smoke obscuration

for the smoke candle test and test 1 (figure 30) shows that this is not

the case. The reason for this is that the rates of smoke production are very different. The smoke candle releases a large quantity of smoke in

about three minutes, while the smoldering fire releases smoke slowly for

about an hour. Therefore, the smoke movement due to a smoke candle is

considerably different from that due to either a flaming test or a smoldering test.

5.5.2 Hazardous Conditions

During the three smoldering tests the CO concentration was considerably below the instantaneous threshold and the calculated COHb was well below the critical level. In the first two smoldering tests

(figure 12) smoke obscuration was below the critical level. For test 3 22
when the ventilation system was off the smoke obscuration (figure 13)

was below the critical level throughout the facility except for the burn

room. Even in the burn room the hazard level was not reached until 30

minutes into test 3.

In the low and high energy tests smoke obscuration was more severe. With the exception of test 7 all of these tests were conducted with the

burn room door open. Test 4 was unique in that a fire retarded blanket

was on the bed. With the exception of tests 4 and 7, smoke obscuration

for both the low and high energy tests followed the same pattern, i.e.

smoke from the burn room flowed into the corridor and then into rooms 1

and 3. Obscuration of these spaces reached the critical level at 1 to 3

minutes into each test.

However, the danger due to CO concentration was very different for

the low and high energy tests. The COHb reached the critical level in

the burn room for test 7, a low energy test, at 22.6 min. This measurement was not very meaningful for hazard analysis because it was measured

1.53 m (5 ft) above the floor over the bed in the fire plume. The

critical level of COHb was not reached for any other low energy tests.

However, critical levels of COHb and the instantaneous threshold of CO

were reached for several locations in the test facility during the high

energy tests. The times required to reach the critical level of COHb

and the instantaneous threshold of CO are listed in table 7.

5.5.3 Smoke Detection

Smoke detectors were included in this test series to examine their

performance. The ionization detectors used for this test series were

the same type as used by Bukowski [14] in a study of detector performance in health care occupancies. Bukowski reported activation times

during flaming tests of 15 to 45 s for ionizing detectors in the burn

room and 50 to 115 s for ionizing detectors in the corridor.

23
Throughout this test series smoke detectors were located in the

burn room and the corridor as shown in figure 3. Activation times for

these detectors are listed in table 8. During the smoldering tests the

corridor remained essentially smoke free and accordingly the corridor

detector was not activated. It is well known that the activation time

of ionization detectors is longer for smoke from smoldering fires than

for flaming fires. The activation time during the three smoldering

tests was in the range of 27 to 60 minutes which was considerably

greater than the activation times during the flaming tests.

As expected, the activation times for the low and high energy

flaming tests are for the most part in the same range as those reported

by Bukowski. Test 7 is an obvious exception with an activation time of

over a half hour for the corridor detector. This was because the burn

room door was closed during test 7.

5.6 Interstitial Space Exhaust

The purpose of exhausting the interstitial space in tests 8, 9 and

12 was to prevent smoke in the interstitial space from flowing down into

occupied spaces and thereby causing hazardous conditions. This is

equivalent to saying that the performance of an interstitial space

exhaust system should be such that it subjects the patients to no greater

danger than would occur in a hospital in which the interstitial space

had a solid floor. Room 2 can be considered a room in which a patient

might be subject to smoke flowing through the ceiling from the interstitial space.

Workers who might be in the interstitial space at the time of a fire need to be considered. It is reasonable to expect that maintenance

workers are capable of evacuating under their own power. One criteria

for allowable levels of smoke obscuration and CO concentration in the

interstitial space is that these levels it should be no worse than they

would be without an interstitial space exhaust.

24
Regarding the low energy fires of tests 8 and 9, the following

observations have been made in sections 5.3 and 5.5:

(1) The interstitial space exhaust had little effect on the smoke

obscuration in the interstitial space. Calculated COHb in the

interstitial space was well below the critical level and the

instantaneous threshold of CO was never reached.

(2) The optical densities in the patient rooms and in the corridor

were lower with than without the interstitial space exhaust.

(3) There was no indication of smoke movement from the interstitial

space into room 2

Therefore the interstitial space exhaust system successfully met

the above requirements when it was exposed to a low energy fire in these

tests

Regarding the high energy fire of test 12, the following observations

were made in sections 5.4 and 5.5:

(1) The interstitial space exhaust had little effect on the smoke

obscuration in the interstitial space. The time for calculated

COHb to reach the critical level was essentially the same with

or without the exhaust.

(2) The optical densities in the corridor and in the patient rooms were lower with than without the interstitial space exhaust.

(3) There was some slight smoke movement through the ceiling of

room 2. However, the smoke obscuration was below the critical

level as was the calculated COHb. The CO concentrations never reached the instantaneous threshold in room 2.

25
It can not be said that the exhaust system totally satisfied the

above requirements because there was some smoke movement through the

ceiling during the high energy fires. However, it can be said that this

smoke movement did not result in hazardous conditions in room 2. So, it

would appear that the interstitial exhaust system performed reasonably

well during the high energy fire. In a real hospital where the interstitial space is larger, the result would be to dilute the smoke in the

interstitial space and thus reduce the problem even further.

5.7 Patient Room Exhaust

During test 10 the patient room exhaust system was operating. As

discussed in section 5.3.6, this exhaust reduced smoke concentration in

the corridor and rooms 1 and 3. The door to room 2 was sealed and room

2 remained essentially smoke free throughout the test. This might lead

someone to believe that the patient room exhaust could be used to prevent smoke movement through the interstitial space. However, such a conclusion is unjustified for reasons described below.

The pressure difference across the burn room ceiling for test 10 is

shown in figure 29. The pressure in the first 5 minutes of the test

indicates that the burn room was at a higher pressure than the interstitial space. This would result in smoke flowing from the burn room into

the interstitial space. This positive pressure was due to the buoyancy

of the gas in the burn room as can be seen from the temperature curve

for this test in figure 15. After about 5 minutes the temperature in

the burn room decreased. With the buoyancy forces thus decreased, the

exhaust system dominated air flow across the ceiling. The negative

pressure across the ceiling after 5 minutes (figure 29) indicates flow

from the interstitial space into the burn room. Therefore, except for

the first 5 minutes of this test, no smoke flowed into the interstitial

space. Without similar pressures in room 2, air must have been pulled

by the exhaust fan from the interstitial space into room 2. The fact

that there was so little smoke in the interstitial space explains why

room 2 remained essentially smoke free during test 10.

26
Unfortunately the exhaust system could not be tested during a high

energy fire due to temperature limitations of the fan. This would not

necessarily be the case for real buildings where exhaust fans serving

larger areas would be subjected to lower temperatures due to dilution.

However, observation of the results of the high energy tests can yield

insight into what would happen if a high energy fire was exhausted. It was seen in the first few minutes of test 10 that temperatures of 100° C

in the burn room forced smoke into the interstitial space in spite of

the inhibiting effect of the patient room exhaust system. The higher

temperatures from the high energy tests (figures 25 and 26) would result

in much more smoke being forced into the interstitial space over a longer period of time. In such a situation, the exhaust system would

pull this same smoke, from the interstitial space into room 2. Therefore,

it can be concluded that if the conditions of test 10 were repeated for

a high energy fire, significant levels of smoke would have accumulated

in room 2 . These resulting room 2 concentrations would be even higher

in the case of a longer duration fire, which is frequently the case in

real buildings

5.8 Smoke Movement Paths

During this test series there was smoke movement through (1) open

doorways, (2) the crack under the doors, (3) the exhaust duct system,

and (4) the cracks in the ceiling system. During all high energy tests

and low energy tests except for test 7, there was considerable smoke

movement through the open burn room door into the corridor and from the

corridor into rooms 1 and 3 through open doors. During these tests the

smoke obscuration in the corridor and in rooms 1 and 3 were all in the same range and were considerably higher than the smoke obscuration in

the interstitial space or in room 2. As one might expect, this indicates

that the smoke movement through the open doors is greater than that

through other paths mentioned above.

27
During the smoldering tests, small quantities of smoke were observed

leaking through the crack under the closed burn room door and into the

corridor. However, the resulting smoke obscuration in the corridor was

negligible. During tests 5, 6, and 8 smoke was observed flowing from

the corridor into room 2 through the crack under the door to room 2.

Although, this was the only observed path of smoke movement into room 2 during these tests, and the resulting smoke obscurations in room 2 were

significant. For test 9 the cracks around the door to room 2 were

sealed, and smoke was observed flowing into room 2 through the exhaust

duct (exhaust system not operating) . The resulting smoke obscuration in

room 2 was considerably lower during this test than when the door was not sealed. The leakage through the exhaust duct system was less than

that through the crack under the door to room 2. A similar leakage was observed through the exhaust duct system during high energy fire of test

11 .

For test 12, the supply register and the exhaust grill were sealed

in room 2. Smoke traces were observed around the ceiling tile near the

supply register after test 12. These traces indicated that there was

some smoke movement through the ceiling system, however it could not be

determined whether this smoke movement was into or out of room 2. The

smoke obscuration in room 2 during test 12 was quite low. This indicates

that any leakage that might have occurred from the interstitial space

into room 2 through the ceiling system would have been much less that

that through the other smoke movement paths discussed.

6. SUMMARY AND CONCLUSIONS

1. The use of the interstitial space exhaust at a rate of two air

changes per hour as described in this test series will effectively

prevent hazard conditions due to smoke downflow through the suspended

ceiling from the interstitial space during low or high energy fires

represented in this test series. This is discussed in detail in

section 5.6.

28
2. There was an indication of smoke leakage through the ceiling of

room 2 during test 12, a high energy test. While the direction of

the leakage was not determined, it is possible that smoke was leaking into room 2 from the interstitial space. Hazard conditions

in room 2 due to smoke obscuration or due to CO concentrations did

not result. It can be further stated that this leakage was con- siderably less than leakages observed through open doorways,

through cracks under closed doors, and through the exhaust duct

system. This is discussed in section 5.8.

3. Smoldering fires of the type examined in this test series are not a significant problem in hospitals. This is discussed in section

5.2.

4. When the ceiling system was not subjected to high temperatures, the

most significant smoke leakage into the interstitial space was observed flowing through the crack between the wall and the wall

molding of the ceiling suspension system. This was observed in the

smoke candle test and during the first 4 minutes of tests 11 and

12. This leakage existed in spite of the fact that this crack was

filled with an open cell foam.

5. When the ceiling system was exposed to high temperatures the metal

grid system warped and greatly increased the smoke flow through the

ceiling. This is discussed in detail in section 5.4.3.

6. The use of the fire retardant blanket (matrix fiber of 50 percent

vinyl and 50 percent vinyon) on the bed fire of test 4 resulted in

significantly lower temperature and smoke production than the use

of a cotton blanket on the bed fire. This is discussed in section

5.3.1.

29
7 . The use of the patient room exhaust air system reduced smoke

concentration throughout the test facility in test 10 as discussed

in section 5.3.6. During this low energy fire room 2 was virtually

smoke free. However, in the event of a high energy fire significant

smoke levels in room 2 would probably result even with this exhaust

system. The reasons for this statement are discussed in section

5.7.

8. Closing the burn room door for the low energy fire of test 7 resulted in higher CO concentrations in the burn room. Test 7 was

the only low energy test where critical levels of calculated COHb

were reached in the burn room. However, closing the burn room door

did result in lower smoke obscuration and CO concentrations outside

the burner room. This is discussed in section 5.3.6.

9. The movement of smoke produced by a smoke candle is considerably

different than the movement of smoke from a flaming or smoldering

fire. This is discussed in section 5.5.1.

10. The activation times of the ionizing smoke detectors during flaming

tests were found to be consistent with previous work. This is

discussed in section 5.5.3.

7

ACKNOWLEDGEMENTS

Appreciation is expressed to Lionel Issen and William Bailey for

their contributions to the design and construction of the test facility.

Appreciation is also expressed to Warren Hayes, Richard Zile and

Melvin Womble for instrumentating of the test facility and conducting

the experiments. The author is especially appreciative of Warren Hayes

for his effort in developing a highly reproducible smoldering fire.

Thanks are due to Richard Peacock who wrote the computer graphics

30
routine used to generate the graphs in this paper. Thanks are also due

to Sandra Nowstrup for using that routine to generate those graphs.

Special thanks are due to Emil Braun who wrote the computer routines

used for data acquisition and data reduction.

8 . REFERENCES

[1] Fire Resistance Directory, Underwriters Laboratory (Jan. 1980)

[2] McCaffrey, B. J. and Heskestad, G., A Robust Bidirectional Low

Velocity Probe for Flame and Fire Application, Combustion and

Flame, Vol. 26, 125-7, (1976).

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

Ignition Sources, Part 1 Full-Scale Tests and Hazard Analysis, Nat.

Bur. Stand. (U.S.), NBSIR 77-1290, (Sept. 1977).

[4] O'Neill, J. G. and Hayes, W. D., Full-Scale Fire Tests with

Automatic Sprinklers in a Patient Room, Nat. Bur. Stand. (U.S.),

NBSIR 79-1749, (June 1979).

[5] O'Neill, J. G. and Hayes, W. D., Full-Scale Fire Tests with

Automatic Sprinklers in a Patient Room - Part II, Nat. Bur. Stand.

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

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

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

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

[7] Jin, T., Visibility through Fire Smoke, Main Reports on Production,

Movement and Control of Smoke in Buildings, pp. 100-153, Japanese

Association of Fire Science and Engineering (1974)

31
[8] Steward, R. D. , et al, Experimental Human Exposure to High

Concentrations of Carbon Monoxide, Architectural Environmental

Health, Vol . 26, 1-7 (Jan. 1973).

[9] Parker, J. E., Jr. and West, V. R. , Bioastronautics Data Book, NASA

SP-3006, Chapter II, Scientific and Technical Information Office,

NASA (1973)

[10] Alarie, Y. and Zullo, P., Predicting Carboxyhemoglobin for Different

Patterns of Carbon Monoxide Exposure, Industrial Health Foundation

Symposium on Carbon Monoxide, pp 18-46, Pittsburgh, Pa (1974)

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

Toxicological Parameters during Fire Exposure, Journal of Fire and

Flammability/Combustion Toxicology, Vol. 1, 4-41 (Feb. 1974).

[12] Stewart, R. D., The Effect of Carbon Monoxide on Man, Journal of

Fire and Flammability/Combustion Toxicology, Vol. 1, 167-176 (1974).

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

Fire Protection Assn., Boston, MA (1957).

[14] Bukowski, R. W. , Tests on the Performance of Automatic Fire Detectors

in Health Care Occupancies - A Preliminary Report, Nat. Bur. Stand.

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

32
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G> LO G) LO G) LO G> LO G)

G> LO 00 G) n- LO 00

C\J ,

,

,

s> S> G)

c^/aco Nonvdnosao

uu

Figure

12.

Smoke

obscuration

in

the

burn

room

and

the

interstitial

space

for

tests

1

and

2.
CD

<S> LO

<S

^r

<s

co

Q

(\J

<5>

Q

£> LO LO O L

s» LO O h- LO 00 s> r- LO 00

00 ,

,

0 © O

r\

C

£

LlI 21H

I—

c^/aco Nonvanosao

^5

Figure

13.

Smoke

obscuration

in

the

burn

room

and

the

interstitial

space

'For

tests

2

and

3.
0091

cj 93 a) 3aniva3dW3i

Figure

14.

Upper

gas

temperatures

for

tests

4

through

7.
1600

G)

CO

LO

(\J

G>

OJ

r\

C

E

LO w

LlJ

z:H

I—

g>

- LO

G>

G) G) G) G) G) G) G) G) G)

G) G) G) G> G) G) G) G)

OO CO LO OO C\J

| 1

CO 93a>

i 3dnivd3dW3i

_i i i

| i G> G) G) G> G) G) G) G)

G> G> G) G) G) G> G)

OJ G) 00 CO 00

W

<DL

D

-4-> 0

• LG)

CD —

a

E X

0) 0)

-+J 0

0

(/) L

0 X

0-4J

LOO

0)a w

Q.-P

X w

<D

• -»-> LO— L

0

d)t+-

L

0

0)

X

cj 93 a) 3amva3dW3i

47
G)

oo

LO

OJ

G)

C\J

r\

C

E

LO vy

LU

21H

G)

LO

G>

g> LO g> LO LO © LO G)

G> r- LO OJ 
 LO CJ

OJ ,

,

0 G> G>

LO

"0

c

0

to -4->

to

(1)

L

0

4-

C

0

-4-> 0

L

D

0

to _Q

0

0

E

(/)

<0

(1) L

0

U)

Li_

c^/ao) Nonvanosao

bQ
cw/ao) Nonvmosao

i>9
00 lN30d3d

LOW

<DL04-Wc00L

-pc

<D0c00

~0X0c0£c0

_QL0o

00

<dLD

U)

Ll

50
ovaco Nonvanosao

51
r G>

00

OC _

LO

x E

LU ^ §

d

<+- I—

O GO

in<

O JXkJ

Z<LICQ

LO

OJ

G>

00

r\

C

E

LO

LU

z:H

©

LO

hG>

G) LO G> LO Q LO © LO ©

G) r- LO 00 © r- LO 00

C\J -*r— .r— G) G) G)

c^/gcd Nonvanosao

52

Figure

20.

Smoke

obscuration

for

test
t

r

2

o

..o

nq: h

I-Z2

cn cn o

LIDO

HZ2

COOIO UDO

I— CQ 01

G>

00

U)

(\J

G)

<\l

r\

C

E

L0

^

LU

z:H

I—

G)

UO

G>

G> OO (0 ^r C\J G)

G) G) G) G)

C\J

Q)

L

D

CD

00 INdOddd

53

Carbon

monoxide

concentrations

for

tests

6

and

7.
CD LO CD LO Q LO G> LO <S> Q LO 00 Q r- LO 00

C\1 Q Q <3

ovacD Nonvdnosao

5

1*

Figure

22.

Smoke

obscuration

for

test
00 !N30d3d

CM

CDL

D

U)

Li53

Carbon

monoxide

concentrations

For

tests

6

and

7.
oo

c^/gcd Nonvanosao

5 ^

Figure

22.

Smoke

obscuration

for

test
© LO © LO © LO © LO ©

© LO 00 © LO C\i

00 -

© © ©

cw/aco Nonvmosao

55

Figure

23.

Smoke

obscuration

for

test
© LO © LO © Si) © LO ©

© Lf) CVJ © r- LO (\S

CM -r— © © ©

cvacD NQiivmosao

56
ovaco Nonvmosao

55

Figure

23.

Smoke

obscuration

for

test
© LO 0 ID LO G> LO G)

G) LO (\l CD r- LO 00

(NJ ,— G) G> 
 cw/aco Noiivanosao

56
Q L

g> LO G> LO G> LO G>

G> in 00 G> LO 00

00 ,

G) G) G)

c^/aco Nonvanosao

55

Figure

23.

Smoke

obscuration

for

test
c^/aco Nonvanosao

56
1600

L

g G G g G g G) G) G)

g G g G Q G) G G

oo r- (0 LO CO 00

CO 030) 3dfUVd3dW31

G G) G G G G G G

G G G) G G G G

C\J G OO (Q <\J

r\

C

E

LU

z:H

I—

W

<D

L

0

<+-w

CDL

D

-p

0

L

CDa

E

Q)

1-

L

C\J

L

D

D)

Li_

C3 930) 3dniVd3dW31

57
1600

co 93 a) 3dnivd3dU3i

' i i i

' _i

Q g G G G G G G G G G G G> G G G G

00 r- CO L

m

- CO CM

G G G G G G G G

G G G G G G G

M" CM G OO <0 CM

C 3 93a) 3dniVd3dW31

58
G> LO G) LO g> LO G) LO G)

G> r- LO C\J G> LO CM

C\] ,

G> G) G)

ovaco Nonvanosao

59
00 IN30&3d


 oo CO ^r C\1 G> o <S> 
 <s

60
C 0 cD 33N3d3 J JIG 3dRSS3dd

G>

c

CD0

£

0

0

L

c

L

D

_Q

W

(/) 0

L

0

0

CD0

c

<DL

CD tf-

**- ~0

0

L

D

W

W

Q)L

CL

<\J

"0

c

0

Q

to -p

w

0

-p

L

0

<+-

O)

00

0

L

D

U)

Li61
Q

<0

©

L

©

©

00

©

CM

©

©

© UO © ljo © L

© L0 © © r- L0 CM © If) CM

CM x— x— X— © © ©

r\

C

£

\y

LU

z;H

bc w /ao) Nonvanosao

62

Figure

30.

Smoke

obscuration

for

the

smoke

candle

test

and

test

1
Table 1. Fan Schedule

Fan

Number

Capacity

(cfm) Type Use

1 500 Centrifugal Supply

2 500 Centrifugal Exhaust

3 300 Radial

4 120 Radial Ventilation

5 120 Radial of inter6 300 Radial stitial space

6 3
Table 2. List of Instrumentation

Number Thermocouples

00

01

02

03

04

05

06

07

08

09

10

11

12

13

14

15

16

17

18

19

20

23

24

25

11A

12A

Burn room 0.1 m (4 in) below ceiling

Burn room 0.2 m (8 in) below ceiling

Burn room 0.3 m (12 in) below ceiling

Burn room 0.4 m (16 in) below ceiling

Burn room 0.8 m (31 in) below ceiling

Burn room 1.2 m (3.9 ft) below ceiling

Burn room floor

Burn room doorway 0.1 m (4 in) below top

Burn room doorway 0.1 m (4 in) above floor

Burn room floor under bed

Burn room floor under wastebasket .... Burn room 0.13 m (5 in) below ceiling^.

Burn room 1.53 m (5.0 ft) above floor . Burn room 0.81 m (32 in) above floor

Room 1 - 1.53 m (5.0 ft) above floor

Room 2 - 1.53 m (5.0 ft) above floor

Room 3 - 1.53 m (5.0 ft) above floor

Corridor 1.53 m (5.0 ft) above floor

Corridor 0.13 m (5 in) below ceiling

Interstitial space 0.76 m (30 in) below top

Interstitial space 0.13 m (5 in) below top..

Window of room 1 - 0.1 m (4 in) below top

Window of room 2 - 0.1 m (4 in) above bottom

Outside air

( 1 )

Burn room doorway 0.1 m (4 in) below top ( 2 ) Burn room doorway 1.53 m (5.0 ft) above floor ( 2 )

Number Smoke Meters

30

31

32

33

34

35

36

37

38

39

30A

31

( 1 )

( 1 ) Burn room 0.13 m (5 in) below ceiling

Burn room 1.53 m (5.0 ft) above floor'

Burn room 0.81 m (32 in) above floor

Room 1 - 1.53 m (5.0 ft)

Room 2 - 1.53 m (5.0 ft)

Room 3 - 1.53 m (5.0 ft)

Corridor 1.53 m (f.O ft)

above floor

above floor

above floor

above floor

Corridor 0.13 m (5 in) below ceiling

Insterstitial space 0.76 m (30 in) below top

Insterstitial space 0.13 m (5 in) below t^p

Burn room doorway 0.1 m (4 in) below top

Burn room doorway 1.53 m (5.0 ft) above floor ( 2 )

These instruments were only used for tests 1-3.

These instruments were used for tests 4-6 and 8-10.

6k
Table 2. List of Instrumentation (cont'd)

Numb er CO Probes

40

41

42

43

44

(3) Burn room 1.53 m (5.0 ft) above floor

Room 1 - 0.81 m (32 in) above floor

Room 2 - 0.81 m (32 in) above floor

Room 3 - 0.81 m (32 in) above floor

Interstitial space 0.76 m (30 in) below top^

Number Velocity Probes

50

51

54

55

Burn room doorway 0.1 m (4 in) below top

Burn room doorway 0.1 m (4 in) above bottom.

Window of room 1 - 0.1 m (4 in) below top . . Window of room 1 - 0.1 m (4 in) above bottom'

Number Differential Pressure

56 Across burn room ceiling

These instruments were only used for tests 1-3.

These instruments malfunctioned during test 8.

65
Table

3.

Test

Schedule cOuo e S o o o 3 3 3

>4-1 4-4 o X X 4-> 3 a) 0) > > 0 O o 3 6 e cfl 0) 00 3 00 i—i 0 3 3 3 3 0 3 •H •H

eg CO r—

CO t—3

(3 <u •H 3 •H 3 3 1—

3 I—

3 3

PS •r4 3 •rH 3 X 4-1 4-1 3 0 0 3

00

O 00

O 3 3 O a O 3

•H 3 •H 3 3 i—

rH

•H 3 •H 3 3

d) 3 (1) 3 0 O 3 a 3 3 0 0 t—

04 CN P

4-1 i—

CO cd 3

•H cO

4-1 ,3 •H X 4-4 4-4 4-1 44

4-1

W 44 4-4 4-1 44

CO o o O

O

u 3

cu CJ

4-1 cO a co M c/o0

4-1 d)

CO 4-1 2 CO 4-4

cd Oo 3 3 4-4 3

rG cn

OO o O

Xw 0

•H

<303

O'* 4-> rH CO 4-1 p to 3 3 4h 3 P C/0 O O o O 3

C/0 •H< t—

b

X o 3 S X) 3 3 a 3 o 3 d) 3 a) O o •H P P a i—

Pi & O

O o O 0oo 1-1 X X T3

PS o 3 3 CU o CO CO CO 3 0 Q o o O 3

(-4 0 t—

rH P 3 a C_> CJ O

CQ 3 00 00 bO >4 p 3 3 a oo

Oo •r-4 •H •H 3 H 3 3 U 3 3 3 (U 3

4-1 X)

X "d

W CO i—

t—4 rH c

O O o & 0 0 0 0 O

C/0 C/0 CO 4 1 1 4-1 CO I—

04 CO <r

cu 3 X3PP o 3 3 3 3 3 3 O 3 3 3 3 O 3 O X 3 X 3 3

-3B 04

O 3 0 3

r-l

OO 3 3 O 3

03 3 3

00

O . 3 3 3 X O 3 4-4

0!3 3O 30O 3 ' r' 3 3 3 3 3

in 3 3 0 3 3 3 0 F—S 3 3 a 3 3 r-4 3 O 3 03 3 44 H U

4H 4H 44 Ol Ol 4h 4-1 4-1 Ci 3 O o O C> O '

4-4 4-r 4-1 4-1 3 4-4 4-1 4-f 4-1 O o o o o

4-1 4-1 4-1 4-1 3 4-1 4H 4-1 4-1 O o O o o

"O "d 'd

CD <U cu cu <u

CO CO CO CO CO O o o o o i—1 tH rH t—i \

1 u CJ CJ CJ a 3 3

"d

cuCO 3 3 3 3 o 3 3 p £

rH P P O O O O

Oo P

00 oo 00 00 00 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 W W W W W s & 5 5 s o O o o o 0 0 0 0 0 m cD ro 00 CO

"dC

cd CM 3 g 3 O 3 O 3 3 3 3 1 -H

CO CO X)

co CO 3 3 3 0 3 3 3 3 3 3 3

CO

O 3 3 X 0 0 3 •rH i—

3 3 3 0 3 3 3 0 O 3 3 3 3 0 0 00 3 3 3 3 3 Oo 0 3 3 0 3 3 3 P

Oo P 0 0 0 3 O O O 3 3 P P 033OoX

4-1 44 CM 3

4-1 44 3 O O O O •H333X3303X3

44 0 3 3 44 O o o • r X33Oi—

U33&

44 44 0 3 • 44 44 0 O /-V O o o O 0 X 4-1U

CM

O 0 rH O r—

O3 X X X CO 3 3 3 • r« \ CO CO 3 3 o* O O O 3 i—

i-4 i—p CN o O CJ O m 3 . CO 3 X cd 3 3 £

15 3O <u 3 0 H 3 3 cd 3 3 3 O u 3 3 3 O 3 P P P X 3 4-1 O O O 3 CO cn 5 d

cd

X 0 rC 3 O X 3 o cu Oo Oo 3 P 00 00 0 cu 00 3 3 0 3 a 3 3 3 3 cd 3 3 3 O 3 a 3 W W O 0 co W 0 0 3 3 *H

15 00 00 3 0 cd O *H •H 3 3 •H 0 35 X 3 0

4J 3 •H O 4-> i—

3 CO 0 0 u 3 cu X 4-1

O rH CM 3 3 c

iH I—

i—

0 3 M i—

CN 66
Table 4. Ignition Source

Wastebasket — Polyethylene wastebasket

Size: 248 mm x 178 mm x 254 mm high

Weight: 282 g (.6 lb)

Trash contents, in order of stacking

1

— Polyethylene liner

16 — Sheets of newspaper

1 — Paper cup, 85 g (3 oz.), crumpled

2 — Sheets of writing paper

3 — Tissues, paper handkerchief, crumpled

1 — Cigarette pack, crumpled

1 — Milk carton, 227 g (8 oz.)

2 — Paper cup, 85 g (3 oz.)

,

crumpled

1 — Cigarette pack, crumpled

1 — Sheet of writing paper, crumpled

2 — Tissues, paper handkerchief, crumpled

Total weight of contents: 443 g (.97 lb)

Combined weight, wastebasket and contents: 725 g (1.6 lb)
Table 5. Technical Data for Mattress and

Bedding for Tests 4-10

'{ t Total

Size (m) Weight

Mattress Width Length Thickness (kg)

Fire Retardant

Cotton Innerspring 0.91 2.03 0.17 23

Bedding Item

Size

Width

(m)

Length Composition

Total

Weight

(kg)

Fire Retardant

Blanket 2.29 1.68

Matrix Fiber

50% vinyl

50% vinyon

1.41

(2) Cotton Blanket 2.29 1.68 Cotton 1.54

Sheet 2.74 1.96 65% Polyester

35% Cotton

0.65

Pillow Case 0.91 0.53 65% Polyester

35% Cotton

0.13

Pillow 0.69 0.52 Cotton Cover,

Duck Feather

Filling

1.50

Fire retardant

2 Cotton blanket

blanket used in test 4 only,

used in tests 5-10.

68
Table 6. Technical Data for Mattress and Bedding

for Tests 11 and 12

Total Weight

Size (m) Weight Combustibles

Mattress Width Length Thickness (kg) (kg)

Polyurethane

Innerspring 0.89 2.03 0.17 15 6

Bedding Item

Size

Width

(m)

Length Composition

Total

Weight

(kg)

Spread 2.79 1.93 50% Cotton

50% Polyester

1.07

Sheet and

Drawsheet 2.64 1.83

50% Cotton

50% Polyester 0.60

Pillow Case 0.91 0.53 50% Cotton

50% Polyester

0.60

Pillow

- Filling

- Cover 0.69 0.52

Polyurethane

Cotton

0.67

0.16

Pillow 0.69 0.53 Polyvinyl chloride 0.90

Protector

69
Table 7 . Times to Hazard Level Due

to CO Concentrations

Test Space

Time

COHb

>25%

(min)

CO

>1%

7 Burn Room 22.6 -

11 Burn Room - 4.7

11 Room 1 9.2 -

11 Room 3 9.5 -

11 Interstitial Space 19 -

12 Burn Room^^ - -

12 Room 1 9.8 -

12 Room 3 11.1 -

12 Interstitial Space 18 -

‘'‘CO analyzer failure.

70
Table 8. Smoke Detector Activation Times

Test Test Type

Time

Burn Room

(sec)

Corridor

1 Smoldering 3567 N/A

2 Smoldering 2679 N/A

3 Smoldering 1604 N/A

4 Low Energy 43.7 71.2

5 Low Energy 37.2 49.4

6 Low Energy 15.2 26.7

7 Low Energy 20.0 2024

8 Low Energy 34.9 53.1

9 Low Energy 54.5 72.3

10 Low Energy 54.4 66 .

11 High Energy 20.4 37.4

12 High Energy 22.0 42.6

Note: N/A = not activated during test

71
NBS-1T4A (rev. 2 -ec) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OR

REPORT NO.

NBSIR 81-2444

2. Performing Organ. Report No, 3. Publ i cation Date

February 1982

4. TITLE AND SUBTITLE

SMOKE MOVEMENT THROUGH A SUSPENDED CEILING SYSTEM

5. AUTHOR(S)

John H. Klote

6. PERFORMING ORGANIZATION (If joint or other than NBS. see instructions)

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8 . Type of Report & Period Covered

Final Report

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

and

Veterans Administration

Office of Construction Research

Washington, D.C. 20420

Department of Health and Human Services

Washington, D.C. 20201

10.

SUPPLEMENTARY NOTES

! J Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11.

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

bi bliography or literature survey, mention it here)

A series of full-scale tests were conducted to evaluate smoke movement

through a suspended ceiling and into an interstitial space of a hospital type

facility. A test facility specifically constructed for this project is

described. The test series consisted of one smoke candle test and 12 fire

tests including both smoldering and flaming fires. Smoke movement through

the suspended ceiling system was evaluated in terms of the total smoke

movement through the test facility. The effects of ventilation and smoke

exhaust on smoke concentration in the test facility were investigated.

12.

KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Ceiling systems; hazard analysis; hospitals; interstitial space; mattresses;

smoke control; smoke exhaust; smoke movement; ventilation systems

13.

AVAILABILITY

[^Unlimited

1 | For Official Distribution. Do Not Release to NTIS

PJ Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

py] Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

77

15. Price

$ 10.50

USCOMM-DC 6043-P80

iJ1I