ASTM E1591-00
(Guide)Standard Guide for Obtaining Data for Deterministic Fire Models
Standard Guide for Obtaining Data for Deterministic Fire Models
SCOPE
1.1 This guide describes data required as input for mathematical fire models.
1.2 Guidelines are presented on how the data can be obtained.
1.3 The emphasis in this guide is on compartment zone fire models.
1.4 The values stated in SI units are to be regarded as the standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation: E 1591 – 00
Standard Guide for
Obtaining Data for Deterministic Fire Models
This standard is issued under the fixed designation E 1591; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 472 Practice for Reporting Thermoanalytical Data
E 473 Terminology Relating to Thermal Analysis
1.1 This guide describes data required as input for math-
E 537 Test Method for Assessing the Thermal Stability of
ematical fire models.
Chemicals by Methods of Differential Thermal Analysis
1.2 Guidelines are presented on how the data can be
E 603 Guide for Room Fire Experiments
obtained.
E 793 Test Method for Heats of Fusion and Crystallization
1.3 The emphasis in this guide is on compartment zone fire
by Differential Scanning Calorimetry
models.
E 906 Test Method for Heat and Visible Smoke Release
1.4 The values stated in SI units are to be regarded as the
Rates for Materials and Products
standard.
E 967 Practice for Temperature Calibration of Differential
1.5 This standard does not purport to address all of the
Scanning Calorimeters and Differential Thermal Analyz-
safety concerns, if any, associated with its use. It is the
ers
responsibility of the user of this standard to establish appro-
E 968 Practice for Heat Flow Calibration of Differential
priate safety and health practices and determine the applica-
Scanning Calorimeters
bility of regulatory limitations prior to use.
E 1142 Terminology Relating to Thermophysical Proper-
2. Referenced Documents ties
E 1321 Test Method for Determining Material Ignition and
2.1 ASTM Standards:
Flame Spread Properties
C 177 Test Method for Steady-State Heat Flux Measure-
E 1354 Test Method for Heat and Visible Smoke Release
ments and Thermal Transmission Properties by Means of
Rates for Materials and Products Using an Oxygen Con-
the Guarded-Hot-Plate Apparatus
sumption Calorimeter
C 518 Test Method for Steady-State Heat Flux Measure-
E 1623 Test Method for Determination of Fire and Thermal
ments and Thermal Transmisson Properties by Means of
Parameters of Materials, Products, and Systems Using an
the Heat Flow Meter Apparatus
Intermediate Scale Calorimeter (ICAL)
C 835 Test Method for Total Hemispherical Emittance of
Surfaces from 20 to 1400°C
3. Terminology
D 2395 Test Methods for Specific Gravity of Wood and
3.1 Definitions—For definitions of terms appearing in this
Wood-Base Materials
guide, refer to Terminology E 176.
D 3286 Test Method for Gross Calorific Value of Coal and
Coke by the Isoperibol Bomb Calorimeter
4. Significance and Use
D 3417 Test Method for Heats of Fusion and Crystallization
5 4.1 This guide is intended primarily for users and develop-
of Polymers by Thermal Analysis
6 ers of mathematical fire models. It is also useful for people
E 176 Terminology of Fire Standards
conducting fire tests, making them aware of some important
E 408 Test Methods for Total Normal Emittance of Surfaces
7 applications and uses for small-scale fire test results. The guide
Using Inspection-Meter Techniques
thus contributes to increased accuracy in fire model calcula-
tions, which depend greatly on the quality of the input data.
4.2 The emphasis of this guide is on zone models of
This guide is under the jurisdiction of ASTM Committee E-5 on Fire Standards
compartment fires. However, other types of mathematical fire
and is the direct responsibility of Subcommittee E05.33 on Fire Safety Engineering.
models need many of the same input variables.
Current edition approved April 10, 2000. Published May 2000. Originally
published as E 1591–94. Last previous edition E 1591–94.
NOTE 1—Mathematical fire models in this guide are referred to by their
Annual Book of ASTM Standards, Vol 04.06.
acronyms (see 5.4).
Annual Book of ASTM Standards, Vol 04.10.
Annual Book of ASTM Standards, Vol 05.05.
Annual Book of ASTM Standards, Vol 08.02.
6 8
Annual Book of ASTM Standards, Vol 04.07. Discontinued; see 1995 Annual Book of ASTM Standards, Vol 14.02.
7 9
Annual Book of ASTM Standards, Vol 15.03. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1591
5. Summary of Guide Here, air is described simply as containing oxygen and
nitrogen.
5.1 This guide provides a compilation of material properties
and other data that are needed as input for mathematical fire air
C H 1 5~O 1 3.76N ! → 3 CO 1 4H O 1 18.8N
models. For every input variable, the guide includes a detailed
3 8 2 2 2 2 2
reactants products (1)
description and information on how it can be obtained.
5.2 The following input variables are discussed: 6.1, air/fuel
The mass ratio of air to fuel is found to be 686.4/44 5 15.6.
ratio; 6.2, combustion efficiency; 6.3, convective heat transfer Thus, the stoichiometric air to fuel ratio, g , for propane is
s
coefficient; 6.4, density; 6.5, emissivity; 6.6, entrainment found to be 15.6.
coefficient; 6.7, flame extinction coefficient; 6.8, flame spread 6.1.2.2 Some models use an “effective” air/fuel ratio; for
parameter; 6.9, heat of combustion; 6.10, heat of gasification; example, see Ref (1). The main purpose of using an effective
6.11, heat of pyrolysis; 6.12, rate of heat release; 6.13, ignition
ratio different from the stoichiometric ratio is to prevent full
temperature; 6.14, mass loss rate; 6.15, production rate of utilization of oxygen entrained from the lower layer. However,
species; 6.16, pyrolysis temperature; 6.17, specific heat; 6.18,
this ad hoc approach is not generally accepted and validated. A
thermal conductivity; and 6.19, thermal inertia. physically correct method of preventing full utilization of the
5.3 Some guidance is also provided on where to find values entrained oxygen requires the inclusion of an oxygen mass
for the various input variables. balance in the set of model conservation equations. Only the
5.4 A general commentary on zone models for compartment stoichiometric air/fuel ratio is needed in this case, while the
fires and a list of acronyms and data requirements for some combustion submodel accounts for the effects of vitiation and
models are included in Appendix X1. oxygen starvation.
6.1.3 Apparatus to Be Used—There is no direct need for an
6. Data for Zone Fire Models apparatus to determine the stoichiometric air/fuel ratio. The
ratio can be calculated from the stoichiometry of the combus-
6.1 Air/Fuel Ratio:
tion reactions, but this is often not possible since the elemental
6.1.1 Introduction:
composition of the fuel is seldom known. The most common
6.1.1.1 Flames can be characterized as being either pre-
way of determining the stoichiometric air/fuel ratio in actual
mixed or diffusion. Premixed flames can be defined as those
fires or experiments is by calculating the ratio between the
flames that result from the ignition of intimately mixed fuels
amount of energy released by combustion per mass unit of air
and oxidizers. Diffusion flames can be defined as those flames
fully depleted of its oxygen and the heat of combustion. The
that result from the ignition of the fuel within the region in
former is nearly identical for a wide range of materials and
which the originally separate fuel and oxidizer meet and mix.
equal to 3 MJ/kg of air 6 5 %. Methods of determining the
Diffusion flames are by far the more common type of flame to
latter are discussed in 6.9.
be encountered in hostile fire situations. A burning upholstered
6.2 Combustion Effıciency:
furniture item is an example of diffusion flame burning.
6.2.1 Introduction—The effective heat of combustion in
6.1.1.2 The source of the oxidizer in most fires is the oxygen
fires is smaller than the net heat of combustion because of the
contained in normal air. If a flame receives insufficient oxygen
incomplete combustion of fuel vapors. The combustion effi-
to burn all of the fuel vapors present completely, the flame is
ciency, x, accounts for incomplete combustion.
considered to be “oxygen limited” or “oxygen starved.” Sto-
6.2.2 Procedures to Obtain Combustion Effıciency—The
ichiometric burning refers to conditions in which the amount of
ratio between the effective heat of combustion and net heat of
oxygen available in the combustion region exactly equals the
combustion is the combustion efficiency. Thus,
amount required for complete combustion. A fuel-limited flame
Dh
is one for which the amount of oxygen available is greater than
c,eff
x5 (2)
Dh
net
that required for complete combustion of the available fuel
vapors. Fuel-limited flame is sometimes also referred to as
where:
“free burn fire.”
Dh 5 effective heat of combustion, kJ/kg, and
c,eff
6.1.1.3 The air/fuel ratio, g, of a fuel is a measure of the
Dh 5 net heat of combustion, kJ/kg.
c,net
mass of air required per unit mass of fuel being burned. The
The combustion efficiency for most hydrocarbons ranges
effective air/fuel ratio required in some mathematical fire
from 0.4 to 0.9.
models is greater than or equal to the stoichiometric air/fuel
6.2.3 Apparatus to Be Used:
ratio since it reflects the excessive air entrainment associated
6.2.3.1 Test Method D 3286 for Dh (with adjustment for
c,net
with free burning fires.
water vapor; see 6.9); and
6.1.1.4 The air/fuel ratio is used in the fire models to
6.2.3.2 Cone Calorimeter (Test Method E 1354), ICAL
calculate mass burning rates and hence heat release rate. The
Apparatus (Test Method E 1623), or the Factory Mutual Small
air/fuel ratio is unique to each fuel and is dimensionless [that
Scale Flammability Apparatus (2) for Dh (see 6.9).
c,eff
is, mass/mass].
6.3 Convective Heat Transfer Coeffıcient:
6.1.2 Procedures to Obtain Air/Fuel Ratios:
6.3.1 Introduction:
6.1.2.1 As mentioned above, the stoichiometric air/fuel ratio
is derived easily from the chemical balance equation describing
the complete combustion of the fuel in normal air. For
The boldface numbers in parentheses refer to the list of references at the end
example, consider the burning of propane (C H ) gas in air. of this standard.
3 g
E 1591
6.3.1.1 Convective heat transfer refers to the movement of
T 5 wall temperature, K.
w
heat (energy) between a solid surface and a contacting fluid due
(3) Finally, some models (6,7) use an even more complex
to a temperature difference between the two. The modeling of
approach in which the heat transfer coefficient is calculated
convective heat transfer requires the use of a convective heat
from the Nusselt Number (Nu), which is a function of the
transfer coefficient, commonly referred to as h, which can be
Grashof Number (Gr) and the Prandtl number (Pr) in the
defined as follows:
familiar form:
q˙9
hl
y
h [ (3)
Nu [ 5 C ~GrPr! (6)
DT 1
k
where:
where:
q˙9 5 energy transferred per unit area, W/m , and
h 5 convective heat transfer coefficient, W/m ·K,
DT 5 temperature difference between the surface and mov-
l 5 characteristic length of surface, m,
ing fluid, K.
k 5 thermal conductivity of the fluid, W/m·K,
6.3.1.2 The convective heat transfer coefficient commonly C 5 a constant, and
y 5 a constant.
has SI units of W/m ·K; it is a function of the fluid properties
(thermal conductivity, density, and viscosity), nature of the (4) The equation implies that heat transfer is dominated by
fluid flow (velocity and turbulence), and geometry of the solid natural convection. This is not always true and not everywhere
surface. the case in room fires. For example, plume and vent flows
generate significant velocities that drive heat transfer. Since the
6.3.2 Procedures to Obtain the Convective Heat Transfer
velocity is generated external to the heat transfer process, the
Coeffıcient:
convection heat transfer between walls or objects and these
6.3.2.1 General Method:
flows is forced rather than natural. For forced convection, the
(1) The selection of a proper heat transfer coefficient can be
following equation for the Nusselt Number as a function of the
difficult due to the extremely large number of variables that
Reynolds Number (Re) and the Prandtl number shall be used:
must be included in its derivation, even for the relatively small
number of practical situations encountered in mathematical fire hl
x y
Nu [ 5 C Re Pr (7)
k
modeling.
(2) One wishing to obtain values for heat transfer coefficients
where:
generally searches compilations of previously derived values
C 5 a constant, and
for those that best apply to a problem or situation. Examples of
x 5 a constant.
these sources include heat transfer texts (for example, see Ref
6.3.3 Apparatus to Be Used—Unless there is a need (and
(3)). The situation can be further simplified when the fluid is
availability) of a heat transfer coefficient for a specific situa-
air, which of course is the situation generally encountered in
tion, sufficient accuracy should be provided by selecting a
fire modeling. Most fire models assume that smoke behaves
value (or deriving one) judiciously from tabular data (and
like and has physical characteristics similar to those of air.
formulas). If experimental data are desired, the apparatus
(3) For example, the convective heat transfer coefficient for
required may vary depending on the problem being explored.
exchange between a turbulent air flow and a vertical plane can
6.4 Density:
be approximated as follows:
6.4.1 Introduction:
1/3
h 5 0.95~DT! (4) 6.4.1.1 The density of a material is the mass of material per
unit volume. In fire models, density is usually expressed as
where:
kg/m .
h 5 W/m ·K, and
6.4.1.2 There are two reasons for density to change as a
DT 5 temperature difference between the vertical surface
material is heated: volatile (flammable or nonflammable, or
and the air, K.
both) may be lost and dimensional changes (expansion or
6.3.2.2 Default Values in Some Existing Fire Models:
contraction) may occur. Although corrections for temperature
(1) Some models currently have fixed heat transfer coeffi-
dependence can be made (8), many models use constant (room)
cients. Regardless of the conditions within the hot layer, the
temperature values.
coefficient is set at a constant value of approximately 10
6.4.2 Procedures to Obtain Density:
W/m ·K.
6.4.2.1 The density of a material is determined by measur-
(2) Other models, such as CFC V (4) and FIRST (5) use a
ing the mass and physical dimensions (volume) of a sample of
slightly more complex approach wherein the heat transfer
the material. There are detailed ASTM guidelines for certain
coefficient is expressed as a function of the
...
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