Reference

NBS

Publications

NAT'L INST. OF STAND & TECH MRQIR 82-2556

AlllOb SSIMbl Analysis of Smoldering Fires

in Closed Compartments and

Their Hazard Due to Carbon

Monoxide

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

July 1982

-QC

IGG

.U56

82-2556

1982

u s DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

JUL 2 9 1982

NBSIR 82-2556

AN ANALYSIS OF SMOLDERING FIRES

IN CLOSED COMPARTMENTS AND

THEIR HAZARD DUE TO CARBON

MONOXIDE

J. Quintiere, M. Birky, F. McDonald and G. Smith

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

National Engineering Laboratory

Center for Fire Research

Washington, DC 20234

July 1982

U.S. DEPARTMENT OF COMMERCE, Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Director

An Analysis of Smoldering Fires in Closed Compartments

and Their Hazard Due to Carbon Monoxide

by

J.G. Quintiere, M. Birky, F. Macdonald, G. Smith

Abstract

A review was made of smoldering fire experiments conducted in closed

rooms and buildings. The results were summarized by tabulating maximum

levels of CO, the time integral of CO concentration ("dose"), CO

2

, temperature rise and oxygen consumption. A hazard time based on the attainment

of a CO dose equal to 4.5% CO-minutes and the time for transition to

flaming were also tabulated. The likelihood of reaching a critical CO

condition during smoldering seems to be comparable to the likelihood of

having transition to flaming occur. A theoretical model, requiring

inputs of CO production rate and energy release rate, was executed and

compared with available data. The theoretical results for CO concentration

as a function of time were in good agreement with the experimental data.

The model offers a means of extrapolating test data to compartments of

various size in order to assess the general hazard of CO due to smoldering.

Key Words: Carbon monoxide, closed space, review, smoldering fires.
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TABLE OF CONTENTS

Page

INTRODUCTION 2

COMPARTMENT SMOLDERING EXPERIMENTS 3

SELECTING A HAZARD CRITERION 5

THEORETICAL ANALYSIS 10

COMPARISON WITH EXPERIMENTAL RESULTS 13

RISK ASSESSMENT DUE TO SMOLDERING 19

CONCLUSIONS 21

ACKNOWLEDGEMENT 23

NOMENCLATURE 24

REFERENCES 26

LIST OF FIGURES 28

LIST OF TABLES 39
Introduction

The hazard of smoldering fires has been well documented by fire

statistics. Twenty-seven percent of the deaths due to fire in the United

States have been attributed to residential fires involving mattresses or

upholstered furniture initiated by smoking materials [1]. This fire scenario

commences with a smoldering fire propagation which may go through a transition

to flaming fire spread. The fire victims could be in the same room as the

fire or in another room of the dwelling. It is not clear from fire incidence

data whether victims succumb during the smoldering phase or during the possible

subsequent flaming phase.

Although this fire scenario is more than five times as common as any

other [1], its characteristics and behavior have been studied very little.

There are only a few experimental studies for a variety of materials and

furnishings to document the general behavior of smoldering propagation and

its transition to flaming. Consequently the mechanisms for smoldering decomposition and its transition to flaming are not well understood. For example, no

models have been developed to predict the rate of CO evolved or the time for

flaming to occur. Also the dynamics of the flow of combustion products, which

originates at the smoldering source and spreads to the boundaries of the

dwelling space, have not been delineated. A better understanding of these

phenomena could more completely define the parameters which control the hazard

of the "smoldering" fire scenario.

The research that has been done divides into very basic and very applied

studies. The fundamental research has dealt with simple geometric configurations and has led to some insight into the mechanism of smoldering and the

prediction of its propagation [2-8].

2
The applied research has [9-15] considered the smoldering of

furnishing materials in full-scale experiments involving a single room,

several rooms, or even an entire house. Usually, the criterion for

conducting these experiments was realism, e.g,, ignition by a cigarette,

inclusion of blankets, sheets, etc. Typically the temperature and composition

of the accumulated products of combustion were recorded. The mechanism of

smoldering was not addressed in these full-scale experiments, and in nearly

all cases, the rate of mass loss during smoldering was not measured or reported.

The motivation for this investigation was to try to establish a quantitative result of the hazard during the smoldering period of a fire. The

objectives were two-fold: (1) to consolidate for analysis the data

of available full-scale smoldering experiments, and (2) to develop a model

for the prediction of CO concentration in an enclosure subject to smoldering.

Compartment Smoldering Experiments

A review of the literature was made in order to assemble temperature

and concentration data from smoldering fire experiments in compartments. Only

those experiments in which measurements were made in a closed space were

considered. The "closed space" could have been a single room with a closed

door, or an entire house with all external doors and windows closed (or, perhaps,

open a small amount) . The literature review Includes experiments in a single

family house by Bukowski, Christian, and Waterman [9], tests of various

mattress and upholstered chair materials by Hafer and Yuill [10], room tests

3
by Sumi and Wllliams-Lear [11], experiments in a mobile home by Bukowski [12],

and experiments in an apartment by Heskestad [13] and Kung [14]. Recent

experiments conducted at the National Bureau of Standards (NBS) [15] were

also evaluated.

These recent NBS experiments [15] were to serve as a guide for the

developmental of a mathematical model and a basis for its verification. They

2 were conducted in a closed room 2.44 m high and 8.83 m in floor area. The only

opening was a horizontal slit at the floor with dimensions 76 cm by 2.5 cm high.

The smoldered material was either a loosely packed bed of cotton 10 to 15 cm

thick or two adjacent blocks of flexible polyurethane foam designated as GM-21*

15 cm thick. Smoldering was initiated by an electric heater centrally located

within the material. Also a chair of the same type used by Bukowski [12] was

smoldered. In each of these experiments the mass loss was measured along with

temperature and specie concentrations at various positions in the room. The gas

measurements were made between the smoldering material and one wall at heights

of 30.5, 76.2, 168, and 236 cm above the floor. The smoldering material was

placed on a load cell platform which was approximately 33 cm above the floor,

and the ignition point on the chair was approximately 43 cm above its base.

The experimental data reviewed in the literature and obtained in the NBS

study [15] are listed in Tables la and Ib . Table la lists the materials burned,

and the type of enclosure including its volume and ventilation conditions.

Table Tb lists the corresponding experimental critical results during smoldering:

maximum carbon monoxide concentration, minimum oxygen concentration, maximum

carbon dioxide concentration, maximum temperature rise, and the time of transition

to flaming.

*GM is a material from the material bank of the Product Research Committee,

described in Fire Research on Cellular Plastics: The Final Report of the

Products Research Committee, Lib. Cong. No. 80-83306, (1980).

4
Selecting a Hazard Criterion

It is useful to analyze these data in order to establish some basis

for deciding whether the smoldering fire conditions pose a threat to human

safety. The degree of impairment which constitutes a threat is somewhat

subjective. Also many factors bear on the process so that a unique hazard

criterion is not possible to define. Although CO appears to be the principle

hazardous agent of smoldering fires, other combustion products generated can

increase the hazard. They can affect the respiratory rate, in addition to

the normal rate corresponding to the activity of the person. Thus, the

inhaled rate of combustion products will vary, and a specified exposure

to CO is not sufficient to define a unique physiological effect. Despite these

factors, a reasonably distinct condition will be sought so that a hazard

criterion can be expressed solely as a function of the exposure CO concentration. This will provide at least a reference point for discussion.

The basis for determining the hazard caused by exposure to CO is the

concentration of carboxyhemoglobln (COHb) which forms in the blood. This

displaces the oxyhemoglobin, therefore starving the body of oxygen. The degree

to which this occurs has been correlated with the response of healthy adults [16].

The COHB level is usually measured in per cent saturation in the blood with

100% corresponding to the condition in which all of the hemoglobin has

combined with CO to form COHb. For example, 20-40% COHb corresponds to

throbbing or severe headache and nausea, and greater than 50% COHb leads

to coma or death, if untreated [16]. A general formula that describes the

relationship between the exposed CO concentration (x in % volume) and the

conversion to COHb in the blood (z in % saturation in blood) was developed

by Coburn, Foster and Kane [17]. The formula basically is a conservation

equation which states that the rate of COHb (dz/dt) formed is equal to the

5
sum of the inhaled or exogenous component plus the body generated or

endogenous component. In considering extreme effects associated with

combustion products, the endogenous effect is relatively small. Since

the exogenous effect results from the CO partial pressure difference

between the exposure gases and the pulmonary capillaries, it can be a

positive or a negative value. COHb will increase when exposed to a fixed

CO concentration, reaching an equilibrium value in generally several hours.

On subsequent exposure to normal air, COHb will decay to its normal level

in the same manner. Further details of the process can be found in the

literature [16,17]. The following equation can be developed by using the

values for fixed parameters as suggested by Stewart [16] and Zullo [18].

dz

dt

0.69 X 0 . 042z

(lOO-z)

k

V

+ 6.4 X 10 ( 1 )

where z is % COHb saturation,

X is % volume of CO in the exposure gas,

is a ventilation parameter in m£/min-mm Hg,

and t is time in minutes.

The value of k depends on the ventilation rate and therefore the activity

V

level of the person. Zullo [18] provides data such that the following

values for k can be determined for three activity levels:

V

k = V

6.6 m£/mm Hg, resting

15.4 mJl/min-mm Hg, moderate work

24.7 m5-/min-mm Hg, heavy work
A criterion for hazard will be derived from Eq. (1) by making some

approximations. In principle, the activity level, age and health of the

person along with the expsoure concentration of CO will be sufficient to

compute the COHb level as a function of time. A hazard time can then be

found by deciding on a specific unacceptable COHb level. The variations

and uncertainties in these quantities justify approximations in the analysis

in order to arrive at a general criterion. Of course, this result to

follow will only provide a general global reference, and will not be

accurate in specific cases. The approximations are described below:

(1) The threshold for discomfort in healthy adults and a possible

lethal condition for persons with heart disease may be taken

as z = 20%. Hence, by considering 0 ^ z ^ 20 as the range of

interest, Eq. (1) will be linearized by approximating the term

z/ (lOO-z) as z/lOO.

(2) The anticipated range of CO conditions relative to smoldering

fires is 0.01 to 1% (or 100 to 10,000 ppm). Also since the

potential victim is believed to be asleep in many smoldering

fire scenarios, a k^ corresponding to the rest state will be

used. Hence, the endogenous term (6.4 x 10 ^ % COHb/min) will

be negligible compared to the exogenous term. On similar reasoning,

the initial concentration of COHb will be taken as zero.

Thus, Eq. (1) is approximated as follows:

= 6.6 (0.69 X (t) - 0.042 z) (2) at

with z = 0 at t = 0.

7
A general solution is given as

^ ^ g, ^-2.8xl0‘^t

f'"

x(T) dT (3)

Jo

To justify a final approximation, a representative upper time limit of

interest in smoldering fires will be taken as 2.5 hours (150 min.). Also a

power law description will be considered for CO concentration since this is a

good representation for smoldering in closed compartments. That is,

x(t) = at’^. (4)

This is substituted into Eq . (3) along with approximations for the exponentials

-3 since 2.8x10 t is small for t 150 minutes. The result can be written as

z = 0.69 f x(T) dT [l - to - ^ (bt)2] (5)

‘'O

where b = 4.2x10 ^ k min

V

k = 6.6 m£/min-mmHg,

V

j ri and X = at

For smoldering rates to be discussed, it may be reasonable to expect n

between 1 and 3. Such arguments lead to the conclusion that the bracket term

in Eq . (5) can be as low as 0.75 approximately. Considering this effect small

in terms of the precision attributable to an overall hazard criterion, the

following criterion is derived.

D(t)

= J

x(t) dx 20 'V' 4 . 5 % CO - min

(0.69) (6.6)

( 6 )

8
The variable D defined here will be referred to as the CO-dose, and 4.5%-min

represents its critical value relative to hazard. This dose variable can be easily

computed from experimental data or from predicted CO concentrations over time, and

the time at which it attains 4.5%-min defines the degree of hazard. Table Ib

lists the maximum value of D achieved in each experiment, and the time at which

the critical dose is reached.

Unquestionably the criterion for hazard due to CO exposure is somewhat

arbitrary as expressed by Eq. (6). It has been based on some approximations to

the Coburn et al. equation [17], holds for times less than about 150 minutes,

has selected 20% COHb as an "incapacitation" point, and has assumed a human

activity in the resting state. For other conditions, the critical value in

Eq. (6) will change. An increase in the activity level will decrease the

critical value for dose, and the dose integral will overestimate the

physiological effect for times longer than those for which the mathematical

approximations are valid.

Based on this CO hazard criterion and on similar considerations for the

other possible sources of hazard, the general results of Table 1 may be summarized

as follows: The effects of elevated temperature, low oxygen, and high carbon

dioxide levels were not a significant threat to life safety in these limited

experiments; however, the level of carbon monoxide in smoldering can reach a

hazardous level. The onset of flaming, after which hazardous conditions will

very likely result, is a variable event, and the factors which promote its

occurrence are not obvious. Distributions of the times to flaming and the times to

reach the critical (4.5%-min) CO dose are shown in figure 1. Of the forty experiments, 24 resulted in transition to flaming and 17 reached a critical CO dose during

9
smoldering. Of these 17, 10 never developed to the flaming state while the

other 7 did. It appears that hazardous conditions due to CO occur in 50 to

150 minutes and that the transition to flaming is also very likely in this

period. Hence the hazard of smoldering initiated combustion is either the

incapacitation of a person due to the inhalation of CO, or the transition to

flaming combustion which would increase both the CO and temperature levels

of the combustion products. Both of hazards appear to have a similar chance

to occur in a period of 1 to 2-1/2 hours. Which will occur first can not be

answered, since the transition to flaming can not be predicted.

Theoretical Analysis

The model applied to predict the CO concentration in the enclosure is

based on the analysis developed by Zukoski [19] to predict the time required

for a "closed” room to fill with products of combustion from a small fire. The

smoldering phenomenon is treated as a point source of energy and CO which gives

rise to a weakly buoyant plume, and the room is assumed to leak at the floor.

All closed building compartments tend to leak and a floor leak corresponds to

the usual space under a closed door. The plume causes a hot descending layer

in the room and the CO concentration is taken to be uniform in this layer.

A schematic of this process is shown in figure 2.

A tracing sketch taken from a photograph of the actual process is shown

In figure 3. The faintness of the smoke in the plume and hot layer precluded

a distinct photograph for illustration. The sharpness of a hot layer interface

is not always clear, and this concept is less valid as the descending layer

gets close to the floor. Nevertheless, a point source plume is probably a

good model of the smoldering plume but the homogeneous layer assumption may

need more support.

10
The governing equation for the layer height given by Zukoski [19] in

dimensionless variables Is

^ + Q* + = 0 (7a)

for 0 ^ y < 1 with y= 1 at T = 0 and

^ + Q* = 0 (7b)

for - ^ ^ y 5. Once the layer reaches the floor, y

= - L/H for all time

c thereafter. These equations arise from a mass balance on the lower cold volume

of gas in the compartment. The second term in Eq. (7a) represents the leak rate

which is proportional to the energy release rate (Q) of the smoldering source

minus the rate of heat loss from the hot layer which are assumed negligible here.

This term is generally small compared to the third term for smoldering fire sources

while the layer height (H) is above the position of the source (L) . The

third term represents the rate of mass entrained by the plume.

The dimensionless quantities are given as follows:

dimensionless time, T = (H^/S);

dimensionless heat, Q*t = Q/(p T c /gH H ); op ° c c dimensionless layer position, y

= H/H^;

and entrainment parameter, a = 1/5.4.

The floor area is designated by S, and the other geometric variables are

displayed in figure 2.

11
riie L'aLo oT enerj^y release ol; the point source plume is given by

Q

= m AH ( 8 )

where m is the rate of mass loss due to smoldering and AH is the heat of

reaction for the smoldering process. Here, the assumption is made that all

of the energy release due to smoldering is convected away by the plume. Plume

radiation and conduction heat losses in the smoldering material are neglected.

It will be shown that significant uncertainties in the value of AH exist

which overshadow the effect of ignoring these heat losses. Fortunately these

uncertainties seem to have a small impact on the predicted results.

The conservation equation for CO was developed from a control volume

enclosing the hot layer and the plume. The plume was assumed to have negligible

volume, and the density of hot layer was taken as that of the air in the lower

layer. This is consistent with the Boussinesq model for the plume [19] and is

justified by the low temperature rise in smoldering fires as observed from

Table I. By employing the conservation of mass as well, the equation for CO mass

concentration, Y, with or without leakage from the hot layer, follows:

'dT ‘ for 0 < y

< 1 (9a)

dT ^ AH (^)1-y ^ for - < y < 0

H

C

(9b)

where y is the effective stoichiometric mass ratio of CO produced to mass of

material lost.

12
The dose parameter is computed as follows:

( 10)

o

In the theoretical calculations the initial time t^ corresponds to the time

at which the layer interface reaches a specific height of interest. This

height could represent the position of a CO sensor or a likely position

that a person would be at. In analysis of the experimental data of

Table I, t is taken as zero.

A computer program was written to solve equations (7), (9) and (10) numerically. The apparent singularity in Eq. (9a) was avoided by small-time analytical

solutions as shown by Cooper [20]. The rate of mass loss as a function of

time was derived from available experimental data. Two other parameters,

Y and AH, must be specified for the smoldering material. These were also

derived from experimental data. This process will be described.

Comparison with Experimental Results

The two NBS tests [15], T18 polyurethane and T22 cotton, were examined first.

The mass loss rate was determined to be approximately linear in time up until

the fuel limit was reached, i.e..

m = ct ( 11)

2 2 with "c" respectively 0.206 gm/min for the polyurethane and 0.33 g/min for

the cotton. The heat source was taken at L = 0.33m in these calculations.

13
Approximate values for AH were suggested by Ohlemiller [21] as 1.05 kJ/g

for polyurethane and 2.1 kJ/g for cotton. Values for y were then empirically

determined using the upper most probe value for Y (CO) in Equation (9) at a

sufficiently long time such that the hot layer position was at or near the

floor. Thus, the value of y would be approximately equal to (-L/H^). The values

found for y were 0.085 for cotton and 0.11 for polyurethane.

An alternative method was also used to evaluate AH and y for these

materials. This made use of the analytical data taken from the NBS toxicity

"protocol" apparatus [22]. This apparatus consists of a 194 I closed

chamber in which a small sample (several grams) of material is thermally

decomposed in an electric furnace. The cotton and polyurethane materials

examined in the closed room tests were decomposed (without flaming) in this

apparatus. The gas temperature, CO and O

2

concentration measurements, along

with the initial and final mass measurements of the samples, were used to

estimate AH and y. The respective maximum and minimum records for CO and O

2

were associated with the final sample mass at the end of the test. The

parameters were then calculated from

and

y

= m

CO

m - m

o

AH

m

o

m.

( 12 )

(13)

based on the assumption that the constancy of the heat of combustion per

unit mass of oxygen (AH ) holds for these decomposition reactions with a value

^2

of 13 kJ/g O

2 [23]. The other variables in Eqns. (12) and (13) are given as

follows

:

14
- the maximum mass of CO produced

and

- the maximum mass of 0^ consumed

m - the initial sample mass

o m^ - the final sample mass

The results of these calculations for a number of tests with different

initial mass loadings yielded the values listed below:

Cotton: Y 0.11 g/g, AH = 11 + IkJ/g

Polyurethane: y

= 0.10 ^ OOA AH = 15+8 kJ/g

The variation in the values represents the differences among the test

results for different sample loadings. The significance of these results is

their general agreement with the "best fit" values for y from the full-scale

experiments, and their similarity for the two materials. But these derived

Ah values are an order of magnitude higher than the suggested values by

Ohlemiller [21]. Fortunately this uncertainty in AH does not have a great

impact on the computed results produced from the two sets of parameters,

nor on their general agreement with the full-scale data. These comparisons are

shown in Figure 4 for cotton and Figure 5 for polyurethane.

The results in Figures 4 and 5 show the long time scale typical of

smoldering fires. The time at which each probe begins to record an increase in

CO concentration is somewhat apparent from the data. These probe times could

be interpreted as the time corresponding to the descending hot layer of CO.

The clarity of this interpretation is not sufficient to test the predicted

arrival times for the layer. However the general magnitude of the predicted

results may be of interest and therefore are listed below for the polyurethane

test

:

15
prol)e |)osition, y 0.64 0.21 1o o

arrival time for AH=15 kJ/g 150s 480s 1400s

arrival time for AH=1.05 kJ/g 270s 900s 3900s

Similar results are predicted for the cotton test. The order of magnitude

of the predicted times seem to be in agreement with the times suggested by

the data. The long arrival time for the probe near the source, calculated

using the lower estimate for AH, may suggest that the higher value estimates

of AH are more correct. More information is needed to resolve this issue.

The upholstered chair experiment [15] was analyzed next. Only the

data for the sensor near the ceiling will be shown, since these should be

representative of the idealized layer concentration. The predicted CO layer

concentration was based on an experimental smoldering rate of

m

(0.10 g/min^)t + (0.0185 g/min^)t^, 0 < t < 73 min.

(60 g/min^) , 73 £ t ^ 120 min.

(14)

and AH was selected as 1.5 kj/g since the chair was composed of cotton and polyurethane. The "best-fit" value for y found to be 0.11. Based on the previous

discussion for the NBS polyurethane and cotton results, a higher value could

also have been selected for AH. Since the uncertainty in AH appears to have

a small effect on the predicted results, the smaller value was settled on. It

is noted, however, that the "best-fit" value for y is nearly the average of the

previous values found for the pure cotton and polyurethane materials.

The predicted results are compared to the measured CO concentrations in

Figure 6. The predicted height of the hot layer is also plotted as a function
of Lime. XL iniLiaily falls aL a relaLively fast rate due to entrainment

by the plume, then slows as it approaches the idealized heat source at 0.76

m above the floor. It then descends more rapidly as the smoldering rate increases,

reaching the floor at 67 minutes. The test was allowed to proceed for nearly

two hours. Flaming did not occur and the upholostery was almost entirely

consumed.

Since the same chair had been used in the mobile home experiments by

Uulcowski, the mass loss rate given by Eq. (8) was used as a basis for predicting

the CO concentrations in these experiments. A schematic of the mobile home is

shown in Figure 7. The chair was burned in the living room, and CO measurements

were made in tlic hall, 1.5 m above the floor, and in the rear bedroom, 0.9 m

above the floor. Two experiments were compared; MH3 which had the bedroom

doors open, and MH5 which had the doors closed. Doors and windows to the

outside were closed and the forced air ventilation system was off. The previous

values of AH and y for the chair were used, but the source position was taken

at L = 43 cm since the chair rested on the floor in this case. The predicted CO

concentrations for the two experiments are compared with the measured results in

Figure 7. The arrows on the predicted curves indicate the time at which the

idealized hot layer interface reaches the hall sensor (H) for tests MH3 and MH5

and the bedroom sensor (RB) for MH3. As seen, the predicted results are in

good qualitative agreement with the measurements but they are displaced to

the left. Although an attempt was made to use the same ignition procedure for

the chair, this displacement could be due to lack of reproducibility of the

17
i^’niLion and early smoldering propagation. The predicted times for

''triggering'' the sensors are about 5 to 10 minutes too early for the hall

sensor and 5 minutes later for the rear bedroom sensor. In these mobile

home experiments transition to flaming occurred within one hour, but the predicted

results could be extended beyond this time according to Eq. (8). If the

critical dose of 4.5%-min is selected, it can be shown that the two experiments

did not exceed this value before flaming, but the theoretical results would

achieve this critical state in about 70 minutes. In view of the degree of

agreement with the data, these times are probably a reasonable estimate of hazard

for the smoldering chair in the mobile home if flaming does not occur.

Another comparison of theoretical results with experiments was made for

the case of a cotton mattress smoldering in a room. Two tests (JR 4 and 19)

from Bukowski et al. [9] and the test (SW 13) by Hafner and Yuill [10] for a

cotton mattress with a wool blanket were examined. Both rooms were the same

size, but in the case of Hafner et al. two windows were open a small amount

(see Table I). This was a tenuous application of the theory since the mass

loss rate required was not measured for the mattresses. A gross assumption

was made that the rate of heat and CO evolution was same as that measured in

the NBS test for cotton (T22) . The results of this comparison are shown in

Figure 8. The prediction follows the data for at least the first 40 minutes

but then underestimates the CO concentrations of the JR-tests and significantly

overestimates the SW result. Dilution of the room gases by air flow through

the windows and/or a different mass loss rate could explain the lower concentrations after 40 minutes in the SW test. Nevertheless it is surprising that

the initial smoldering rate of both mattresses appears to be similar to that

of the cotton material described by Eq. (8). In any case, more data from

these experiments would have to have been available to draw more definite

conclusions

.

18
Risk Assesment Due to Smoldering

Since the results predicted for the smoldering chair in the mobile home

are credible, the data used to describe the smoldering chair were used in a

series of calculations. A room was considered with the smoldering source at

0.4 m above the floor. The height of the room was kept fixed at 2.4 m and

the floor area was varied to simulate typical residential rooms up to a size

representative of a single storey dwelling. Predicted CO concentrations as a

function of time for various floor areas are shown in Figure 9. A hypothetical

sensor at the mid-height (y=0.4) of the room was used as an indicator of hazard.

The time (t^) for the layer interface to descend to the mid-height and the

critical time (t*) when a dose of 4.5%-min would be ingested are listed on

the figure. It is significant to note that the critical times only vary

by a factor of two for room sizes which vary by a factor of twenty. Morever,

for this chair example, the layer descends to the mid-height more slowly for

larger rooms, but the incremental time (t*-t ) to reach the critical dose

o only varies from 39 to 46 minutes.

It is obvious that these calculated critical times (t*) depend on the

hazard criterion adopted. The 4.5%-min dose could be considered a mild

criterion. If it is increased by a factor of 4 to an 18%-min dose, although

some approximations in developing Eq. (6) would be invalidated, this higher

criterion is likely to correspond to a lethal condition or a serious

incapacitation state [16] . The corresponding critical times would increase to

2 2 71 minutes for the 10 m room and 178 minutes for the 200 m room. This result

2 for the 200 m room assumes the chair continues to smolder at 73 g/min beyond

its known smoldering time of two hours. Thus the higher critical dose criterion

19
increases the hazard times by less than a factor of two. This probably

represents the precision for which hazard times can be predicted since a

hazard level is somewhat subjective.

From Table I a detailed view of smoldering conditions for many experimental

fires has been presented. However, in that form it is difficult to draw general

conclusions from those results. The mathematical model affords a means of

extrapolating results from one test to other conditions, but data are lacking

on mass loss rate and CO production to make these calculations. An attempt to

generalize the experimental and theoretical results for predicting the CO hazard

time is presented in Figure 10. The rationale for selecting the coordinates of

the plot is based on the simplification that the filling process is unimportant.

Then it follows from Eqns. (8) through (11) for a well-mixed space with a

linearly time varying smoldering rate that

D

3 c Y t 6 p V

(15)

where V is the volume of the enclosure. The cubic behavior in time results

from the successive integration of the smoldering rate to obtain CO concentration and then dose. Thus, the critical time based on a dose of 4.5%-min. varies

as the cube root of the volume and inversely as the CO production rate parameter

y. Since y appears to not vary greatly, and a is not generally known, volume

was used as the primary variable in Figure 10. Also since the smoldering rate

will not increase indefinitely in time but is likely to reach a constant value

then decrease as fuel is depleted, the critical time may never be achieved.

Thus the volume of the space was plotted with the reciprocal of the critical

time. These values were determined from Table I. Theoretical results for

the chair used in the NBS experiment (see Eq. (8)) in a room of height 2.4 m

20
with a variable floor area are also plotted. These chair results are

based on the t* values shown in Figure 9. The "JR-data" for a smoldering

cotton mattress in a closed bedroom and for a bedroom open to other portions

of a house tend to parallel the theoretical chair curve. This supports the

credibility of the theoretical curve and suggests a family of similar curves

with each corresponding to a specific smoldering rate. The range of results

for the small volume spaces, indicative of single rooms, reflects the variability

in the smoldering rate. Except for the NBS chair data point, the theoretical

chair result represents an upper bound to the data. If this is true in general,

then the curve could be considered a possible worst case. This suggests that

hazardous conditions would arise as quickly as 50 to 100 minutes for typical

residential rooms and dwellings.

Conclusions

An idealized mathematical model for the prediction of CO in a closed room

due to a smoldering source yields results in good qualitative agreement with

experimental observations and data. Good quantitative agreement appears possible

provided data on the rate of smoldering and CO production are available. These

data are generally lacking and therefore only a limited number of comparisons

were possible. Both theory and experiment suggest that critical conditions

threatening life safety (based on a 4.5%-min dose criterion) tend to arise in

50 to 100 minutes after ignition. This ignores the possibility of transition

to flaming which is not a predictable event at this time.

If the results shown in Figure 1 are representative of accidental fires,

then the smoldering state of a residential fire is a significant contributor to

fire fatalities relative to smoldering fires which go to a flaming state, provided

21
the 4.5%-min dose criterion is accepted as a serious hazard level. If one

uses the 18%-min criterion, then at least ten percent of the available

experimental fires reached this level in the smoldering state. The

conditions arising after transition to flaming would be responsible for

the remainder of the fatalities, and more than half of the experimental fires

reviewed eventually resulted in flaming combustion.

The single-space model suggests that the volume of the space is not a

strong influencing factor on the time to reach a hazardous condition (i.e.,

critical dose time). Data [9] show a two-fold increase in critical time for

a ten-fold Increase in volume. More complete experiments of smoldering in

a residential dwelling need to be examined to determine whether a more sophisticated theoretical model is needed to make predictions. Also the phenomena

of smoldering "smoke" movement in a multi-room space needs to be clearly

established. As these gases cool they will not be driven by the buoyancy

produced from combustion but will follow the natural and forced ventilation

characteristics of the building.

If materials were characterized by their rate of smoldering (m(t)) and

their CO production (y) , the simple model developed here could provide a means

of assessing risk. Characteristic mass loss (or CO production) rates need to

be measured for smolderable materials in their product configuration. Such

a study would quantitatively define the fire problem of smoldering. The use

of "small-scale" tests to measure y values appears feasible, but the constancy of

y and its variation among materials or configurations needs to be explored.

22
Acknowledgement

The authors wish to acknowledge the work of Ken Steckler who developed

the computer program for solving the equations used in the model, and to

Maya Paabo who supplied specie data on the decomposition products of the

cotton and polyurethane materials used in the NBS experiments.

23
Nomenclature

a,b,c

D

c P

g

H

H

c L

m

lii

Q

Q*

s

t

t*

T

Y

X

y

Y

z

a

Y

AH

P

T

fixed parameters,

dose, Eq. (4)

specific heat

ravitational acceleration

vertical distance from source to hot layer

vertical distance from source to ceiling

vertical distance from source to floor

mass loss

mass loss rate

rate of energy release

• 2 dimensionless heat source, Q/ (p T c /gH H

o o p c c floor area

time

critical time at D = 4.5 %-min

Temperature

volume of room

volume concentration of CO in percent

dimensionless distance, H/H

c mass concentration of CO

percent saturation of COHb in blood

entrainment constant, 1/5.4

mass ratio of CO produced to mass loss in smoldering

effective heat of reaction

density of gas

2 dimensionless time, t/g/H (H /S)

c c

24
Subscripts

carbon monoxide

final state

Initial state

oxygen
References

{!] Clarke, F.B. and Ottoson, J., "Fire Death Scenarios and Fire Safety

Planning", Fire Journal , 70, May 1976, p. 20.

[2J Klmbara, T., Hiroshi, E., and Setsuko, S., "Downward Propagation of

Smoldering Combustion Through Solid Material", Eleventh Symposium

(International) on Combustion , The Combustion Institute, 1967, p. 525.

[3] Moussa, N.A. , Toong, T.Y., and Garris, C.A., "Mechanism of Smoldering

of Cellulosic Materials", Sixteenth Symposium (International) on Combustion , The Combustion Institute, 1977, p. 1447.

14] Ohlemiller, T.J. and Rogers, R.E., "A Survey of Several Factors

Influencing Smoldering Combustion in Flexible and Rigid Polymer Foam",

J. Fire Flamm . , 9, Oct. 1978, p. 190.

[5] Ohlemiller, T.J. and Rogers, F.E., "Smoldering Combustion Studies of

Rigid Cellular Plastics", Report to the Product Research Committee,

May 1979.

[6] Davidson, B., Keitelman, E., and O’Such, W., "Smoldering Aspects of

Rigid Polymeric Insulation Foams", Report to the Product Research

Committee, June 1979.

17] Ortiz-Molina, M.G., Mak, A.Y., Tesoro, G.C., and Toong, T.Y.,

"Smoldering Combustion of Cellular Plastics and Its Transition to

Flaming or Extinguishment", Report to the Product Research Committee,

June 1979.

[8] Ohlemiller, T.J., Review of Smoldering, Joint Panel Meeting of the

U.J.N.R. Panel on Fire Research and Safety, National Bureau of Standards,

October 1980.

[9] Bukowskl, R.W. , Christian, W.J. and Waterman, T.E., "Detector

Sensitivity and Siting Requirements for Dwellings", National Fire

Protection Association, NFPA No. SPP-43, August 1975.

[10] Hafer, C.A. and Yuill, C.H., "Characterization of Bedding and Upholstery

Fires", Southwest Research Institute report, SWRI Project No. 3-2610,

March 1970.

[11] Sumi, K. and Wllliams-Lelr , G., "Lethal Effects of Mattress Fires",

National Research Council of Canada, Dlv. of Building Research, Res.

Paper No. 402, May 1969.

[12] Bukowski, R.W. , "Investigation of the Effects of Heating and AirConditioning on the Performance of Smoke Detectors in Mobile Homes",

National Bureau of Standards, NBSIR 79-1915, Oct. 1979.

26
[13] Heskestad, G. , "Escape Potentials from Apartments Protected by Fire

Detectors in High Rise Buildings", Factory Mutual Research Corp.,

FMRC Serial No. 21017, June 1974.

[14] Rung, H.G., Haines, D.M. and Greene, R.E., "Development of Low-cost

Residential Sprinkler Protection, U.S. Department of Commerce, National

Fire Prevention and Control Administration, Grant No. NFPCA 76054,

April 1978.

[15] Smith, G. and Birky, M. (private communications).

[16] Stewart, R.D., "The Effect of Carbon Monoxide on Man", J. Fire and Flamm . Comb. Toxicol Supple ., 1, August, 1974, p. 167.

[17] Coburn, R.F., Foster, R.E. and Kane, P.B., "Considerations of the

Physiological Variables that Determine the Blood Carboxyhemoglobin

Concentration in Man", J. Clin. Invest . 44, No. 11, 1965, p. 1899.

[18] Zullo, P., "Predicing Carboxyhemoglobin for Different Patterns of Carbon

Monoxide Exposure", Master of Science Thesis, Dept, of Occupational Health,

Unlv. of Pittsburgh, 1972.

[19] Zukoski, E.E., "Development of a Stratified Ceiling Layer in the Early

Stages of a Closed-Room Fire", Fire and Materials , 2, April 1978, p. 54.

[20] Cooper, L.Y., "Estimating Safe Available Egress Time in Fires Part II - Governing Equations for a Model and Some Solutions", National Bureau of

Standards (to be published)

.

[21] Ohlemiller, T.J. (private communications)

[22] Birky, M.M. , "Development of a Recommended Test Method for Toxicological

Assessment of Inhaled Combustion Products", National Bureau of Standards,

NBSIR 80-2077, Sept. 1980.

[23] Huggett, C., "Estimation of Rate of Heat Release by Means of Oxygen

Consumption Measurements", Fire and Materials, 4, December 1980, p. 61.

27
List Of Figures

Figure 1. Distribution of Smoldering Experiments in Table I for Occurrence of

Critical CO dose and Transition to Flaming.

Figure 2. Idealization Mathematical Model for Smoldering in a Nearly Closed

Compartment

.

Figure 3. Sketch from a Photograph of a Smoldering Smoke Plume.

Figure 4. Calculated and Measured CO Concentrations for Loosely Packed Bed of

Cotton Smoldering in a Closed Room.

Figure 5. Calculated and Measured CO Concentrations for a Block of Flexible

Polyurethane Foam Smoldering in a Closed Room.

Figure 6. Calculated and Measured Results for a Chair Smoldering in a Closed

Room.

Figure 7. Calculated and Measured CO Concentrations for a Chair Smoldering in a Closed Mobile Home. (S> Chair location. *

Figure 8. Measured Results for Cotton Mattresses Smoldering in a Room Compared

with Calculated Values Based on the Smoldering of Loosely Packed Cotton

Figure 9. Theoretical Results for a Chair Smoldering in Rooms of Various Volume.

Figure 10. A Correlation of CO Critical Time with Room Volume from Table I and

Theory.

28
29

Figure

1.

Distribution

of

smoldering

experiments

in

Table

I

for

occurrence

of

critical

CO

dose

and

transition

to

flaming
CQ

CD

30

Figure

2.

Idealization

mathematical

modeling

for

smoldering

in

a

nearly

closed

compartment
Figure 3. Sketch from a photograph of a smoldering smoke plume

31
(uiddloo

¥

32

Figure

4.

Calculated

and

measured

CO

concentrations

for

loosely

packed

bed

of

cotton
oo

ITi

O

ID

CO

CO

UO

<NB

CM

U

a)

€/)

ID

ID

CO CO CM CM CM

^

(uidd)03

33

Figure

5.

Calculated

and

measured

CO

concentrations

for

a

block

of

flexible

polyurethane

foam

smoldering

in

a

closed

room
HEIGHT

OF

HOT

LAYER

FROM

FLOOR

|m]

0 20 40 60 80 100 120

TIME (mini

Figure 6. Calculated and measured results for a chair smoldering in a closed room

34

CO

CONCENTRATION

|%|
MH5 - Doors closed

MH3 - Doors open

TIME (min)

H - Hall - CD (a) 1.5m above floor

RB - Rear bedroom - CO @ 0.9m above floor

F - Flaming

0

CO

CD

Figure 7. Calculated and measured CO concentrations for a chair smoldering

in a closed mobile home. ® Chair Ipcation

35
A

JR

4

(AC

on)

A

JR

19

(Heat

on]

T T T CM

O

36

Figure

8.

Measured

results

for

cotton

mattresses

smoldering

in

a

room

compared

with

calculated

values

based

on

the

smoldering

of

loosely

packed

cotton
CO

CONCENTRATION

|%

0 20 40 60 80 100 120

TIME (min)

Figure 9. Theoretical results for a chair smoldering in rooms of various

volume

37
Data

Source

0.03

-

o

JR

|9|

V

A

SW

(10|

Can

(11

1

38

Figure

10.

A

correlation

of

CO

critical

time

with

room

volume

from

Table

I

and

theory
List of Tables

Table lA. Summary of Experimental Results for Smoldering in a Nearly

Closed Space.

Table lA. Summary of Experimental Results in a Nearly Closed Space

(continued)

.

Table IB. Summary of Experimental Results for Smoldering in a Nearly

Closed Space.

39
Test Number

SUHHARY OF

Reference

EXPERIMENTAL RESULTS FOR SMOLDERING IN A NEARLY CLOSED SPACE TABLE lA Type of Enclosure* Material (closed space)

Volume of Enclosure

m"’ Ventilation Condition

JR4 9 Cot. mattress Bedroom (BR) 37.0 A.C.

JR5 9 Cot. mattress BR, hall, LR 297.1 A.C.

JR6 9 Cot. mattress BR, 1st & 2nd fir. 370.7 A.C.

JRIO 9 Cot. mattress Bsmt, 1st fir. hall & LR, 2nd fir. 413.2 A.C.

JR12 9 Cot. mattress Bsmt, 1st & 2nd fir. 566.0 A.C.

JRll 9 Cot. box spring Bsmt, 1st fir. LR

& hall, 2nd fir. hall 413.2 A.C.

1R14 9 Chair: cot. , ray.

,

acetate

LR, 1st & 2nd fir. halls, two BR*s 325.5 Heat

.IR15 9 Chair: cot. , ray. LR, 1st & 2nd fir. halls, BR 325.5 None

JR 17 9 Cot. mattress BR, 1st & 2nd fir. 370.7 Heat

JR18 9 Cot. mattress BR, LR, 1st & 2nd fir. halls247.1 None

JR19 9 Cot. mattress BR 37.0 Heat

JR22 9 Chair : cot. , ray. Bsmt, 1st & 2nd fir. 566.0 Heat

JR24 9 Sofa: cot. , ny. Bsmt. 1st & 2nd fir. 566.0 None

JR26 9 Couch: cot., ray., ny. Bsmt, portions of 1st & 2nd fir. 501.0 Heat

two windows

SWl 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheets

Room 38.0 5cm X 91cm

SW4 10 Cot. Inner-spring

mattress, ray. tick;

cot. percale sheets

Room 38.0

SW5 10 Cot. inner- spring mattress, ray. tick;

cot. sheets

Room 38.0

!! !!

S\.’6 10 Cot. inner-spring

mattress, cot. tick;

cot. muslin sheets

Room 38.0

SW9 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheets;

ray. , aery, blanket

Room 33.0 " "

SWIO 10 Cot . inner-spring mattress, ray. tick;

cot. muslin sheets;

cot. blanket

Room 38.0

M

SWll 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheets; polyester blanket

Room 38.0

!!

SWl 3 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheets; wool blanket

Room 38.0 " "

SW18 10 Cot. inner- spring mattress, ray. tick;

cot. muslin sheets; acrylic blanket

(laundered)

Room 38.0

’

SWl 9 10 Cot. inner-spring

mattress, tick; cot. muslin sheet; wool blanket (retarded)

Room 38.0 "

!!

40
SmiMARY OF EXPERIMENTAL RESULTS IN A NEARLY CLOSED SPACE (CONTINUED) TABLE lA

Test Number Reference Material

Type of

Enc losure*

(closed space)

Volume of Enclosure

m Ventilatic Condition

SW21 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheet & feather pillow

Room 38.0

SW23 10 Chair/cushion:

polyu. /fabric : ny. Room 38.0

SW25 10 Chair/cushion

:

rubber /fabric : ny. Room 38.0

SW24 10 Chair/cushion

:

polyu./ fabric: cot. Room 38.0

SW26 10 Chair/cushion:

polyu. /fabric : ny. Room 38.0

SW27 10 Chair/cushion:

polyu. /fabric: acetate

Room 38.0

SW28 10 Chair/cushion:

polyu . /fabric : polypropylene

Room 38.0

Can2 11 Cot. inner-spring

mattress, 1/2 Room 14. 5 None

Can3 11 Cot. inner-spring

mattress, 1/2 Room 14.5 " "

MH03 12 Chair: cot., polyu. Mobile home:

L£. , Kit. , hall. BR, 134.4 ii II

MHO 5 12 Chair: cot., polyu. Mobile home:

LR. , Kit. , hall

99.1 M II

FMl 13 Sofa cushion:

polyu. Apartment 170. Heat

FM2 13 Sofa cushion:

polyu. Apartment 170.

T18 15 Polyu. (two blocks,

15cm thk.) Room 21.5

T22 15 Cot. (10-15 cm thk.) Room 21.5 None

15 Chair: cot,, polyu. Room 21.5 None

*First room listed contains smoldering material; underlined room is measurement location

Note Abbreviations:

A.C.

BRLR

Bsmt

.

kit. cot,

ray.

ny. aery.

polyc'S. polvu.

air conditioning

bedroom

living room basement

kitchen cotton

rayon nylon

acrylic

polyester polyurethane

41
SUMMARY OF EXPERIMENTAL RESULTS FOR SMOLDERING IN A NEARLY CLOSED SPACE TABLE Ib

Test

No.

Max. CO

% TimeMin.

Min. Time

Min.

Max. CO

% TimeMin.

Max. AT

°C Time

Min.

^ Max

/ [C0]dt

° - rain Time

Min.

Critical

Dose Time

Min.

Flaming

Time

Min.

JR4 0.39 93. - - 1.32 92. 27. 93. 11.0 93. 65. 94.5

JR5 0.20 51. - - 0.8 51. 29. 51. 2.2 51. » 51.

JR6 0.095 73. - - 0.45 73. 15. 73. 2.9 73. 00

JRIO 0.23 137. - - 1.25 137. 5. 118. 7.0 140. 125.

JR12 0.16 140. - - 1.05 140. 14. 140. 4.5 140. 140. 00

JRll 0.11 130. - - 0.33 130. 11. 130. 4.0 130. 130.

JR] 4 0.02 100. - - 0.1 100. 13. 100. < 1.0 100. »

JR15 0.03 80. - - 0.06 80. 0. 80. < 1.0 80.

JR17 0.10 70. - - 0.55 70. 11. 70. 2.3 70. o> CO

JR18 0.08 63. - - 0.34 63. 9. 63. 2.2 63. a= »

JR19 0.55 100. - - 2.5 100. 24. 100. 18.0 100. 65. »

JR22 'x. 0 27. - - n. 0 27. 0. 27. < 1.0 27. 27.

JR24 0.01 107. - - 0.11 107. -2. 107. < 1.0 107. 107.

JR26 0.02 84. - - 0.15 84. 3. 85. < 1.0 86. a, 86.

SWl 0.2 121. 20.5 121. 0.5 121. 22. 121. 3.9 121. a. 121.

SW4 0.4 135. 18. 135. 0.3 135. 45. 155. 29.4 200. 110. CO

SW5 0.2 162. 20. 160. 1.0 160. 15. 160. 8.6 160. 130. 162.

SW6 0.15 118. 18.5 118. 1.5 118. 60. 118. 4.0 118. 118.

SW9 0.1 91. 20. 91. 0.5 91. 8. 91. 4.3 91. » 97.

SWIO 0.15 100. 20. 100. 1.0 100. 0. 100. 6.5 100. 85. 100.

SWll 0.15 175. 20. 175. 2.0 175. 15. 175. 5.3 175. 165. 175.

SW13 0.39 220. 18.4 220. 2.8 220. 61. 220. 36.5 220. 70. CO

SVJ18 0.1 114. 20. 114. 1.0 114. 3. 114. 4.8 114. 110. 114.

SWl 9 0.05 190. 20.5 190. 0.5 190. 0. 190. < 1.0 190. » CO

SW21 0.22 180. 20.2 180. 1.2 180. 21. 180. 13.0 180. 60 CO

SV/23 0.05 144. 20. 144. 1.0 144. 17. 144. 3.8 144. 144.

SW25 0.1 65. 20. 65. 1.0 65. 6. 65. 2.5 65. 65.

SW24 0.07 77. 20.4 77. 0.8 77. 0. 77. 2.7 77. 77.

SW26 0.05 152. 20. 152. 1. 152. 4. 152. 2.3 152. CO 152.

SW27 0.15 124. 17. 124. 1.0 124. 11. 124. 6.3 124. 90. 124.

SW28 0.1 22. 20.8 22. 0.02 22. 0. 22. 1.1 22. » 22.

Can 2 0.3 117. 17.6 120. 3.0 120. 24. 118. 11.1 117. 87. CO

Can 3 0.5 108. 16.0 100. 4.8 103. 35. 105. 17.3 108. 69. CO

MH03 0.10 57. - - 0.2 57. 2. 57. 2.2 57. 57.

MH05 0.08 46. - - 0.2 46. 2. 46. 1.0 46. 46.

FMl 0.013 38. 21. 38. 0. 38. 2. 38. < 1.0 39. 39.

FM2 0.011 40. 21. 40. 0.04 40. 3. 40. < 1.0 41. <» 41

T18 0.34 79. - - 0.47 79. 13. 79. 11.5 79. 58. 98.

T22 0.3 92. - - 1.6 92. 12. 75. 11.7 83. 60. CO

- 1.8 116. - - - - - - 90. 116. 36. CO

42
SUMMARY OF EXPERIMENTAL RESULTS FOR SMOLDERING IN A NEARLY CLOSED SPACE TABLE lA

Test Number Ref erence Material

Type of Enclosure*

(closed space)

Volume of Enclosure

m VentilationCondition

JR4 9 Cot. mattress Bedroom (BR) 37.0 A.C.

JR5 9 Cot. mattress ra, hall, LR 247.1 A.C.

JR6 9 Cot. mattress BR, 1st & 2nd fir. 370.7 A.C.

JRIO 9 Cot, mattress Bsrat, 1st fir. hall & LR, 2nd fir. 413.2 A.C.

JR12 9 Cot. mattress Bsrat, 1st & 2nd fir. 566.0 A.C.

JRll 9 Cot. box spring Bsmt, 1st fir. LR

5. hall, 2nd fir. hall 413.2 A.C.

JR14 9 Chair : cot. , ray.

,

acetate

LR, 1st & 2nd fir. halls, two BR's 325.5 Heat

JR15 9 Chair: cot., ray. LR, 1st & 2nd fir, halls, BR 325.5 None

JR17 9 Cot. mattress BR, 1st & 2nd fir. 370.7 Heat

JR18 9 Cot. mattress BR, LR, 1st & 2nd fir. halls

247.1 None

JR19 9 Cot. mattress M. 37.0 Heat

JR22 9 Chair: cot., ray. Bsmt, 1st & 2nd fir. 566.0 Heat

JR24 9 Sofa: cot., ny. Bsmt. 1st & 2nd fir. 566.0 None

JR26 9 Couch: cot. , ray. , ny. Bsmt , portions of 1st & 2nd fir. 501.0 Heat

SWl 10 Cot. inner- spring mattress, ray. tick;

cot. muslin sheets

Room 38.0

two windows

5cm X 91cm

SW4 10 Cot. inner-spring

mattress, ray. tick;

cot. percale sheets

Room 38.0 It II

SW5 10 Cot. inner-spring

mattress, ray. tick;

cot. sheets

Room 38.0 M II

II II

SW6 10 Cot. inner-spring

mattress, cot. tick;

cot. muslin sheets

Room 38.0 It tl

II It

SW9 10 Cot. inner-spring

mattress, ray, tick;

cot. muslin sheets;

ray. , aery, blanket

Room 33.0 II II

II It

SWIO 10 Cot, inner-spring

mattress, ray. tick;

cot. muslin sheets;

cot. blanket

Roora 38.0

SWll 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheets; polyester blanket

Room 38.0

„

SWl 3 10 Cot, inner-spring

mattress, ray. tick;

cot. muslin sheets; wool blanket

Room 38.0

„

SW18 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheets; acrylic blanket

(laundered)

Room 38.0

„

SWl 9 10 Cot. inner-spring

mattress, tick; cot. muslin sheet; wool blanket (retarded)

Room 38.0
SUMMARY OF EXPERIMENTAL RESULTS IN A NEARLY CLOSED SPACE (CONTINUED) TABLE lA

Test Number Reference Material

Type of Enclosure*

(closed space)

SViI21 10 Cot. inner-spring

mattress, ray. tick;

cot. muslin sheet & feather pillow

Room

SW23 10 Chair/cushion

polyu. /fabric : ny. Room

SW25 10 Chair /cushion: rubber/fabric: ny. Room

SW2A 10 Chair /cushion: polyu./ fabric: cot. Room

SW26 10 Chair/cushion;

polyu. /fabric ; ny. Room

SW27 10 Chair/cushion:

polyu. /fabric : acetate

Room

SW28 10 Chair/cushion

polyu . /fabric : polypropylene

Room

Can2 11 Cot. inner-spring

mattress, 1/2 Room

Can3 11 Cot. inner-spring

mattress, 1/2 Room

MH03 12 Chair: cot., polyu. Mobile home:

LR. , Kit. , hall.

MH05 12 Chair: cot., polyu. Mobile home:

LR. . Kit. , hall

FMI 13 Sofa cushion:

polyu. Apartment

FM2 13 Sofa cushion:

polyu. Apartment

T18 15 Polyu. (two blocks,

15cra thk.

)

Room

T22 15 Cot. (10-15 cm thk.) Room

- 15 Chair: cot., polyu. Room

*First room listed contains smoldering material; underlined room is measurement location

Note Abbreviations:

A.C.

BR

LR

Bsmt.

kit. cot.

ray.

ny. aery. polyes.

polyu.

air conditioning

bedroom

living room basement

kitchen cotton

rayon nylon

acrylic

polyester

polyurethane

Volume of

Encltjsure

38.0

38.0

38.0

38.0

38.0

38.0

38.0

14.5

14.5

134.4

99.1

170.

170.

21.5

21.5

21.5

Vent ilnt ion

(k>ml i t ion

None

Heat

None

None
SUMMARY OF EXPERIMENTAL RESULTS FOR SMOLDERING IN A NFARLY CLOSED SPACE TABLE Ib

Test

No.

Max. CO

% Time

Min.

Min. Time

Min.

Max, Time

Min.

Max. AT

°C Time

Min.

^ Max

/ [CO]dt

° - min Time

Min.

Critical

Dose Time

Min.

Flaming

Time

Min.

JR4 0.39 93. - - 1.32 92. 27. 93. 11.0 93. 65. 94.5

JR5 0.20 51. - - 0.8 51. 29. 51. 2.2 51. 51.

JR6 0.095 73. - - 0.45 73. 15. 73. 2.9 73. »

JRIO 0.23 137. - - 1.25 137. 5. 118. 7.0 140. 125. OO

JR12 0.16 140. - - 1.05 140. 14. 140. 4.5 140. 140.

JRll 0.11 130. - - 0.33 130. 11. 130. 4.0 130. 130.

JR14 0.02 100. - - 0.1 100. 13. 100. < 1.0 100.

JR15 0.03 80. - - 0.06 80. 0. 80. < 1.0 80. 00

JR17 0.10 70. - - 0.55 70. 11. 70. 2.3 70. »

JR18 0.08 63. - - 0.34 63. 9. 63. 2.2 63. OO

JR19 0.55 100. - - 2.5 100. 24. 100. 18.0 100. 65. „

JR22 'X/ 0 27. - - % 0 27. 0. 27. < 1.0 27. 27.

JR24 0.01 107. - - 0.11 107. -2. 107. < 1.0 107. 107.

JR26 0.02 84. - - 0.15 84. 3. 85. < 1.0 86. « 86.

SWl 0.2 121. 20.5 121. 0.5 121. 22. 121. 3.9 121. » 121.

SW4 0.4 . 135. 18. 135. 0.3 135. 45. 155. 29.4 200. 110. «

SW5 0.2 162. 20. 160. 1.0 160. 15. 160. 8.6 160. 130. 162.

SW6 0.15 118. 18.5 118. 1.5 118. 60. 118. 4.0 118. » 118.

SW9 0.1 91. 20. 91. 0.5 91. 8. 91. 4.3 91. 00 97.

SWIO 0.15 100. 20. 100. 1.0 100. 0. 100. 6.5 100. 85. 100.

SWll 0.15 175. 20. 175. 2.0 175. 15. 175. 5.3 175. 165. 175.

SWl 3 0.39 220. 18.4 220. 2.8 220. 61. 220. 36.5 220. 70. »

SW18 0.1 114. 20. 114. 1.0 114. 3. 114. 4.8 114. 110. 114.

SWl 9 :0.05 190. 20.5 190. 0.5 190. 0. 190. < 1.0 190. „ OO

SW21 0.22 180. 20.2 180. 1.2 180. 21. 180. 13.0 180. 60 OO

SW23 0.05 144. 20. 144. 1.0 144. 17. 144. 3.8 144. 144.

SW25 0.1 65. 20. 65. 1.0 65. 6. 65. 2.5 65. 65.

SW24 0.07 77. 20.4 77. 0.8 77. 0. 77. 2.7 77. 00 77.

SW26 0.05 152. 20. 152. 1. 152. 4. 152. 2.3 152. 152.

SW27 0.15 124. 17. 124. 1.0 124. 11. 124. 6.3 124. 90. 124.

SW28 0.1 22. 20.8 22. 0.02 22. 0. 22. 1.1 22. » 22.

Can 2 0.3 117. 17.6 120. 3.0 120. 24. 118. 11.1 117. 87. CO

Can 3 0.5 108. 16.0 100. 4.8 103. 35. 105. 17.3 108. 69. OO

MH03 0.10 57. - - 0.2 57. 2. 57. 2.2 57. 00 57.

MHOS 0.08 46. - - 0.2 46. 2. 46. 1.0 46. » 46.

FMl 0.013 38. 21. 38. 0. 38. 2. 38. < 1.0 39. » 39.

FM2 0.011 40. 21. 40. 0.04 40. 3. 40. < 1.0 41. 41

T18 0.34 79. - - 0.47 79. 13. 79. 11.5 79. 58. 98.

T22 0.3 92. - - 1.6 92. 12. 75. 11.7 83. 60. OO

- 1.8 116. - - - _ _ _ 90. 116. 36. OO
NBS»]14A (REV. 2 «ec) U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See instructions)

1. PUBLICATION OP

REPORT NO.

NBSIR 82-2556

2. Performing Organ. Report No.| 3. Publication Date

July 1982

4. TITLE AND SUBTITLE

An Analysis of Smoldering Fires in Closed Compartments and Their

Hazard Due to Carbon Monoxide

5. AUTHOR(S)

J. Quintiere, M. Birky, F. McDonald, & G. Smith

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

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

10. SUPPLEMENTARY NOTES

[^21 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

bibliography or literature survey, mention it here) ^ review was made of smoldering fire experiments

conducted in closed room and buildings. The results were summarized by tabulating

maximum levels of CO, the time integral of CO concentration ("dose"), C02> temperature

rise and oxygen consumption. A hazard time based on the attainment of a CO dose equal

to 4.5% CO-minutes and the time for transition to flaming were also tabulated. The

likelihood of reaching a critical CO condition during smoldering seems to be comparable

to the likelihood of having transition to flaming occur. A theoretical model, requiring

inputs of CO production rate and energy release rate, was executed and compared with

available data. The theoretical results for CO concentration as a function of time

were in good agreement with the experimental data. The model offers a means of

extrapolating test data to compartments of various size in order to assess the general

hazard of CO due to smoldering.

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) Building fires; carbon monoxide; compartment fires; smoldering

13. AVAILABILITY

Uni imited

I I For Official Distribution, Do Not Release to NTIS

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

20402.

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

14. NO. OF

PRINTED PAGES

42

15. Price

$ 7.50

USCOMM-OC 6043-P80 Ik