ASTM D5424-23a

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D5424 − 23a
Standard Test Method for
Smoke Obscuration of Insulating Materials Contained in
Electrical or Optical Fiber Cables When Burning in a Vertical
Cable Tray Configuration
This standard is issued under the fixed designation D5424; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope* 1.10 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
1.1 This is a fire-test-response standard.
standard. (See IEEE/ASTM SI 10.)
1.2 This test method provides a means to measure the
1.11 This standard does not purport to address all of the
smoke obscuration resulting from burning electrical insulating
safety concerns, if any, associated with its use. It is the
materials contained in electrical or optical fiber cables when
responsibility of the user of this standard to establish appro-
the cable specimens, excluding accessories, are subjected to a
priate safety, health, and environmental practices and deter-
specified flaming ignition source and burn freely under well
mine the applicability of regulatory limitations prior to use.
ventilated conditions.
1.12 Fire testing is inherently hazardous. Adequate safe-
1.3 This test method provides two different protocols for
guards for personnel and property shall be employed in
exposing the materials, when made into cable specimens, to an
conducting these tests.
ignition source (approximately 20 kW), for a 20 min test
1.13 This standard is used to measure and describe the
duration. Use it to determine the flame propagation and smoke
response of materials, products, or assemblies to heat and
release characteristics of the materials contained in single and
flame under controlled conditions, but does not by itself
multiconductor electrical or optical fiber cables designed for
incorporate all factors required for fire hazard or fire risk
use in cable trays.
assessment of the materials, products, or assemblies under
1.4 This test method does not provide information on the
actual fire conditions.
fire performance of electrical or optical fiber cables in fire
1.14 This international standard was developed in accor-
conditions other than the ones specifically used in this test
dance with internationally recognized principles on standard-
method, nor does it measure the contribution of the cables to a
ization established in the Decision on Principles for the
developing fire condition.
Development of International Standards, Guides and Recom-
1.5 Data describing the burning behavior from ignition to
mendations issued by the World Trade Organization Technical
the end of the test are obtained.
Barriers to Trade (TBT) Committee.
1.6 The production of light obscuring smoke is measured.
2. Referenced Documents
1.7 The burning behavior is documented visually, by pho- 2
2.1 ASTM Standards:
tographic or video recordings, or both.
D1711 Terminology Relating to Electrical Insulation
1.8 The test equipment is suitable for making other, D5537 Test Method for Heat Release, Flame Spread, Smoke
optional, measurements, including the rate of heat release of
Obscuration, and Mass Loss Testing of Insulating Mate-
the burning specimen, by an oxygen consumption technique rials Contained in Electrical or Optical Fiber Cables When
and weight loss. Burning in a Vertical Cable Tray Configuration
E84 Test Method for Surface Burning Characteristics of
1.9 Another set of optional measurements are the concen-
Building Materials
trations of certain toxic gas species in the combustion gases.
E176 Terminology of Fire Standards
E800 Guide for Measurement of Gases Present or Generated
During Fires
This test method is under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.17 on Fire and Thermal Properties. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved May 1, 2023. Published May 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1993. Last previous edition approved in 2023 as D5424 – 23. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D5424-23A. the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5424 − 23a
E1354 Test Method for Heat and Visible Smoke Release 4. Summary of Test Method
Rates for Materials and Products Using an Oxygen Con-
4.1 This fire-test-response standard determines a number of
sumption Calorimeter
fire-test-response characteristics associated with smoke obscu-
IEEE/ASTM SI 10 Standard for Use of the International
ration resulting from burning the materials insulating full-scale
System of Units (SI): The Modern Metric System
specimens of electrical or optical fiber cables located in a
2.2 NFPA Standards:
vertical cable tray and ignited with a propane gas burner. This
NFPA 70 National Electrical Code
test method is also suitable for making other, optional
NFPA 289 Standard Method of Fire Test for Individual Fuel
measurements, including rates of heat release, total amounts of
Packages
heat released, rates and concentrations of carbon oxides
2.3 Underwriters Laboratories Standards: released, and rates and amounts of mass of the specimen lost
(see Appendix X2). Further optional measurements are also
UL 1581 Reference Standard for Electrical Wires, Cables,
and Flexible Cords possible.
UL 1685 Vertical Tray Fire Propagation and Smoke Release
4.2 The vertical cable tray that holds the specimen is located
Test for Electrical and Optical Fiber Cables
in an enclosure of specified dimensions.
UL 2556 Wire and Cable Test Methods
4.3 A hood, connected to a duct, is located above the fire
2.4 Canadian Standards Association Standards:
enclosure. Smoke release instrumentation is placed in the duct.
CSA Standard FT-4 Vertical Flame Tests: Cables in Cable
Heat and gas analysis release instrumentation (optional) is also
Trays, Section 4.11.4 in C22.2 No. 0.3, Test Methods for
placed in the duct.
Electrical Wires and Cables
4.4 Two different test procedures are specified (Protocol A
2.5 IEEE Standards:
and Protocol B), which differ in the burner used and in the
IEEE 1202 Standard for Flame Testing of Cables for Use in
electrical or optical fiber cable loading. These reflect details of
Cable Tray in Industrial and Commercial Occupancies
three existing test methods: UL 1581 (vertical tray flammabil-
2.6 Other Standards:
ity test, now transferred to UL 2556; corresponding to Protocol
CA Technical Bulletin 133 Flammability Test Procedure for
A) and CSA Standard C 22.2 No. 0.3 (FT4 vertical tray
Seating Furniture for Use in Public Occupancies, January,
flammability test), or IEEE 1202 (both corresponding to
protocol B) and UL 1685 (corresponding to both protocols).
Nordtest Method NT Fire 032 Upholstered Furniture: Burn-
Both test procedures described in detail in this test method are
ing Behavior—Full Scale Test
also identified in UL 2556.
ISO 13943 Fire Safety–Vocabulary
5. Significance and Use
3. Terminology
5.1 This test method provides a means to measure a variety
3.1 Definitions—For definitions of terms used in this test
of fire-test-response characteristics associated with smoke
method and associated with fire issues, refer to Terminology
obscuration and resulting from burning the electrical insulating
E176 and ISO 13943. In case of conflict, the definitions given
materials contained in electrical or optical fiber cables. The
in Terminology E176 shall prevail. For definitions of terms
specimens are allowed to burn freely under well ventilated
used in this test method and associated with electrical insula-
conditions after ignition by means of a propane gas burner.
tion issues, refer to Terminology D1711.
5.2 Smoke obscuration quantifies the visibility in fires.
3.2 Definitions of Terms Specific to This Standard:
5.3 This test method is also suitable for measuring the rate
3.2.1 sample, n—an amount of the cable type and construc-
of heat release as an optional measurement. The rate of heat
tion to be tested, which is representative of the product for test.
release often serves as an indication of the intensity of the fire
3.2.2 specimen, n—the individual length of cable, or cable
generated. Test Method D5537 provides means for measuring
bundle, to be placed in the cable tray, which is representative
heat release with the equipment used in this test method.
of the product to be tested.
5.4 Other optional fire-test-response characteristics that are
measurable by this test method are useful to make decisions on
fire safety. The most important gaseous components of smoke
Available from National Fire Protection Association (NFPA), 1 Batterymarch
are the carbon oxides, present in all fires. They are major
Park, Quincy, MA 02169-7471, http://www.nfpa.org.
Available from Underwriters Laboratories (UL), 333 Pfingsten Rd.,
indicators of the toxicity of the atmosphere and of the
Northbrook, IL 60062-2096, http://www.ul.com.
completeness of combustion, and are often used as part of fire
Available from Canadian Standards Association (CSA), 5060 Spectrum Way,
hazard assessment calculations and to improve the accuracy of
Mississauga, ON L4W 5N6, Canada, http://www.csa.ca.
heat release measurements. Other toxic gases, which are
Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org.
specific to certain materials, are less crucial for determining
Available from Bureau of Home Furnishings and Thermal Insulation, State of
combustion completeness.
California, Department of Consumer Affairs, 3485 Orange Grove Ave., North
Highlands, CA 95660-5595.
5.5 Test Limitations:
Available from Nordtest, P.O. Box 22, SF-00341, Helsingfore, Finland, 1987.
5.5.1 The fire-test-response characteristics measured in this
Available from International Organization for Standardization (ISO), 1, ch. de
test method are a representation of the manner in which the
la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
www.iso.ch. specimens tested behave under certain specific conditions. Do
D5424 − 23a
FIG. 1 Cable Test Enclosure
not assume they are representative of a generic fire perfor- 6.1.2.2 In case of disputes, the referee method are the tests
mance of the materials tested when made into cables of the conducted using the enclosure in 6.1.2.
construction under consideration.
6.1.3 Walls—The maximum conductive heat flux loss of the
2 2
5.5.2 In particular, it is unlikely that this test method is an
walls of the structure is 6.8 W/(m K) (30 Btu/h-ft ), based
adequate representation of the fire behavior of cables in
upon an inside wall temperature of 38 °C (100 °F) and an
confined spaces, without abundant circulation of air.
outside air temperature of 24 °C (75 °F). Paint the interior
5.5.3 This is an intermediate-scale test, and the predictabil-
surface of the walls flat black. Any materials of construction
ity of its results to large scale fires has not been determined.
that meet the preceding requirements are acceptable. Two
Some information exists to suggest that it has been validated
examples of acceptable construction materials are nominally
against some large-scale scenarios.
152 mm (6 in.) thick concrete masonry blocks (density:
−3 −3
1700 kg ⁄m (106 lb/ft ) and thermal conductivity nominally
6. Apparatus
k = 1.75 W/(m K), at 21 °C; 12.13 Btu in./ft h °F, at 70 °F),
6.1 Enclosure:
or nominally 13 mm (0.5 in.) gypsum board, with 89 mm 6
6.1.1 The enclosure in which the specimen is tested is
6 mm (3.5 in. 6 0.25 in.) of standard fiberglass insulation, with
shown in Fig. 1.
an R value of 1.94 m K/W (which corresponds in practical
6.1.2 The enclosure has a floor area of 2.44 m 6 25 mm by
units to an R value of 11 h ft °F/Btu). Windows for observation
2.44 m 6 25 mm, with a height of 3.35 m 6 25 mm (8 ft 6
of the fire test are allowed in the walls; ensure that the total area
1 in. by 8 ft 6 1 in. by 11 ft 6 1 in. high). On top of the walls
2 2
of the windows does not exceed 1.86 m (20 ft ).
there is a pyramidal collection hood with a collection box.
6.1.3.1 Select materials of construction which can withstand
6.1.2.1 Other enclosure sizes, such as 2.4 m by 2.4 m by
the high temperatures and presence of open flame within the
2.4 m (8 ft by 8 ft by 8 ft) or the 3 m cube are permitted,
test enclosure and duct.
provided that the internal volume of the enclosure, exclusive of
3 3
6.1.4 Provide air intakes at the base of two opposite walls,
the pyramidal hood, ranges between 14.5 m and 36 m
3 3 2
one of which contains the access door. Ensure that the total
(512 ft and 1272 ft ), the floor area ranges between 6 m and
2 2 2 4 4
9 m (97 ft and 64 ft ), and the maximum air movement cross sectional area of the air intakes is 1.45 m 6 0.03 m
2 2
within the enclosure complies with 6.1.10 (Note 1). (2250 in. 6 50 in. ), and that the intake areas are divided
approximately equally. Fig. 1 shows dimensions for the air
NOTE 1—There is, as yet, not enough information as to the equivalence
intakes installed in the walls. Air intakes are not permitted in
on smoke release between the various facilities. Further work needs to be
done to confirm this. either of the other two walls.
D5424 − 23a
6.1.5 Construct a door with wired glass and locate it as
shown in Fig. 1. The door is 900 mm 6 25 mm wide and
2100 mm 6 25 mm high (35 in. 6 1 in. by 83 in. 6 1 in.), with
an overall conductive heat flux loss no greater than that of the
2 2
walls, that is, 6.8 W ⁄(m K) (30 Btu/h-ft ). A steel framed wired
glass door will meet these requirements. Adequately seal the
sides and the top of the door to prevent drafts.
6.1.6 Construct a truncated pyramid stainless steel hood,
formed as shown in Fig. 1, and locate it on top of the enclosure
walls. Make the slope on each side of the hood 40°. Form a seal
between the hood and the walls; a compressible inorganic
batting as gasket is suitable.
6.1.7 Insulate the exterior of the hood to make an overall
conductive heat loss no greater than that of the walls.
FIG. 2 Bidirectional Probe
6.1.8 Locate a cubical stainless steel collection box
(914 mm 6 25 mm (36 in. 6 1 in.) per side) on top of the
exhaust hood, with a nominal 406 mm 6 25 mm (16 in. 6
6.2.3 Place probes for sampling of combustion gas and for
1 in.) diameter stainless steel pipe exhaust duct centered in one
measurement of volume flow rate in the exhaust duct leading
side.
from the hood.
6.1.9 Install the exhaust duct horizontally and connect it to
6.3 Instrumentation in the Exhaust Duct:
the plenum of the hood.
6.3.1 The following specifications are minimum require-
6.1.10 Ensure that the maximum air movement within the
ments for exhaust duct instrumentation. Additional information
enclosure, with only the intake and exhaust openings open, the
is found in Annex A3.
exhaust fan on, and the burner off, does not exceed 1 m/s
6.3.2 Flow Rate Measurement—Measure the flow rate in the
(3.3 ft ⁄s), as measured by a vane-type anemometer in the
exhaust duct by means of a bidirectional probe, or an equiva-
following areas: (1) at the floor level where the burner is
lent measuring system, with an accuracy of at least 66 % (see
positioned during the test, and (2) at 1.50 m 6 0.05 m (4.9 ft
Annex A3 for further details). The response time to a stepwise
6 2 in.) above the enclosure floor, where the cable tray is
change of the duct flow rate shall not exceed 5 s to reach 90 %
positioned during the test.
of the final value.
6.3.3 Use a bidirectional probe or an equivalent measuring
6.1.11 Construct a square 610 mm 6 25 mm (24-in. 6
1-in.) baffle, centered over the cable tray. An acceptable height system to measure pressure in the duct. Locate the probe
shown in Fig. 2 in the exhaust duct, at least 4.6 m (15 ft) but
is 300 mm to 400 mm (12 in. to 15 in.) above the tray.
no more than 13.7 m (45 ft) from the centerline of the
6.1.12 Construct a collection-exhaust system consisting of a
collection box. Ensure that the minimum length between any
blower, steel hood, duct, bidirectional probe, thermocouple(s),
bend and the probe is at least eight times the inside diameter of
oxygen measurement system (optional), smoke obscuration
the duct. If the system is positioned at a different location,
measurement system, and gas analysis system (optional).
demonstrate the achievement of equivalent results.
Ensure that the system for collecting the combustion products
6.3.4 Build the probe of a short stainless steel cylinder
has the capacity and is designed in such a way that all of the
44 mm (1.75-in.) long and 22 mm (0.875-in.) inside diameter
combustion products leaving the burning specimen are col-
3 −1 with a solid diaphragm in the center. The pressure taps on
lected. Make the exhaust system capacity at least 2.7 m s at
either side of the diaphragm are also the support for the probe.
normal pressure and at a temperature of 25 °C 6 2 °C.
Position the axis of the probe along the centerline of the duct.
Construct the collection-exhaust system as explained in Annex
Connect the taps to a pressure transducer able to resolve
A2 and Annex A3.
pressure differences of 0.25 Pa (0.001 in. of water).
6.2 Exhaust Collection System:
6.3.5 Measure gas temperatures in the vicinity of the probe
with Inconel sheathed Chromel-Alumel thermocouples. Ensure
6.2.1 Construct the exhaust collection system with the
that the thermocouple does not disturb the flow pattern around
following minimal requirements: a blower, steel hood, duct,
the bidirectional probe. Further details are discussed in A3.1.
bidirectional probe, thermocouple(s), and a smoke obscuration
measurement system (white light photocell lamp/detector or
6.4 Smoke Obscuration Measurements:
laser). Construct the exhaust collection system as explained in
6.4.1 Install an optical system for measurement of light
Annex A2 and Annex A3.
obscuration across the centerline of the exhaust duct. Deter-
6.2.2 Ensure that the system for collecting the combustion
mine the optical density of the smoke by measuring the light
products has sufficient exhaust capacity and is designed in such transmitted with a photometer system consisting of a white
a way that all of the combustion products leaving the burning
light source and a photocell/detector or a laser system for
specimen are collected. Design the capacity of the evacuation measurement of light obscuration across the centerline of the
system such that it will exhaust minimally all combustion gases exhaust duct. Locate the system so that it is preceded by at least
leaving the cable specimen (see Annex A2, A2.1.4). eight diameters of duct without bends, to ensure a nearly
D5424 − 23a
the load cell. The gypsum board shall be clean before the start
of a test; if the sheet used has been damaged it shall be
replaced.
NOTE 2—A square galvanized steel platform of dimensions of up to
1.22 m by 1.22 m (approximately 4 ft by 4 ft), with a raised lip, is also
acceptable.
6.6 Burner:
6.6.1 Use a 254 mm (10-in.) strip or ribbon-type propane
gas burner with an air/gas Venturi mixer.
6.6.2 The flame-producing surface of the burner consists
essentially of a flat metal plate that is 341 mm (13 ⁄16 in.) long
and 30 mm (1 ⁄32 in.) wide. The plate has an array of 242 holes
drilled in it. The holes are to be 1.35 mm (metric drill size:
1.35 mm) or 0.052 in. (No. 55 drill) in diameter, on 3.2 mm
(0.125-in.) centers in three staggered rows of 81, 80, and 81
FIG. 3 Optical System
holes each, to form an array measuring 257 mm by 5 mm
1 3
(10 ⁄8 in. by ⁄16 in.). Center the array of holes on the plate (see
Fig. 5).
uniform velocity across the duct section. If the system is
6.6.3 Protocol A:
positioned at a different location, demonstrate the achievement
of equivalent results. 6.6.3.1 Position the burner behind the cable tray containing
6.4.2 One photometer system found suitable consists of a the specimen, with the flame-producing surface (face) of the
lamp, lenses, an aperture, and a photocell (see Fig. 3 and A3.2). burner vertical and its long dimension horizontal, and with the
Construct the system so that soot deposits on the optics during 257 mm (10 ⁄8-in.) dimension of the array of holes spaced
76 mm 6 5 mm (3.0 in. 6 0.2 in.) from the specimens in the
a test do not reduce the light transmission by more than 5 %.
6.4.2.1 Alternatively, instrumentation constructed using a tray and centered midway between the side rails of the tray.
Position the centerpoint of the array of holes at 457 mm (18 in.)
0.5 mW to 2.0 mW helium-neon laser, instead of a white light
system, is also acceptable. See Fig. 4 and A3.2 for further above the bottom end of the tray and specimen and midway
between two rungs. Support the burner in a manner to enable
details. White light and laser systems give similar results
(1-4). the burner to be quickly removed and precisely returned to the
position described. The burner faces the doorway.
6.5 Cable Tray:
6.6.4 Protocol B:
6.5.1 Use a steel ladder cable tray, 300 mm 6 25 mm (12 in.
6.6.4.1 Mount the burner on a stand and place it 20° 6 2°
6 1 in.) wide, 75 mm 6 6 mm (3 in. 6 0.25 in.) deep, and
from the horizontal with the burner ports up, in front of the
2440 mm 6 25 mm (8 ft 6 1 in.) long. Arrange the tray so that
cable tray. Locate the major axis of the burner ports 305 mm 6
the burner flame will impinge on the cables midway between
25 mm (12 in. 6 1 in.) above the base of the cable tray and
rungs.
parallel to the cable tray rungs during the fire test (Fig. 6). The
6.5.1.1 Each rung in the tray is to measure 25 mm 6 6 mm
burner faces the doorway.
(1 in. 6 0.25 in.) in the direction parallel to the length of the
tray and 13 mm 6 3 mm (0.5 in. 6 0.125 in.) in the direction 6.6.4.2 Attach a guide to the burner or stand such that the
leading edge of the burner face is located quickly and accu-
parallel to the depth of the tray.
6.5.1.2 Space the rungs 230 mm 6 13 mm (9 in. 6 0.5 in.) rately 76 mm 6 5 mm (3 in. 6 0.2 in.) horizontally away from
the nearest surface of the cables during the burn period of the
apart (measured center to center).
6.5.1.3 Attach the rungs to the side rails. test.
6.5.1.4 Mount the cable tray vertically in the center of the
6.6.5 Insert a flowmeter in both the propane and the air lines
enclosure. Position the tray on a tray base (stand), which is to
feeding the burner to measure the flow rates of these gases
be no higher than 152 mm 6 25 mm (6 in. 6 1 in.).
during the test.
6.5.2 Place a square galvanized steel platform under the
6.6.6 Use a propane flowmeter capable of measuring at least
3 3 3
cable tray. The platform shall be constructed of nominally
230 cm /s (29 ft /h) and an air flowmeter of at least 1330 cm /s
1.6 mm ( ⁄16 in.) thick steel, and have dimensions of no less
(170 ft /h). Flow rate measurements shall be accurate to within
than 1.0 m by 1.0 m (approximately 39 in. by 39 in.), with a
3 %. Mass flow controllers with recordable outputs are permit-
uniform raised lip 100 mm (approximately 4 in.) high, on each
ted alternatives.
side, to catch falling material. The platform shall be covered by
a tight fitting sheet of standard gypsum board, of nominally
13 mm (0.5 in.) thickness. If a load cell is placed underneath
The sole source of supply of the apparatus known to the committee at this time
the cable tray (as optionally in X2.1), the platform shall protect
is a burner supplied by American Gas Furnace Company, Inc., of Elizabeth, NJ,
Catalog No. 10 L11–55, with an air/gas Venturi mixer, Catalog No. 14–18. If you are
aware of alternative suppliers, please provide this information to ASTM Interna-
The boldface numbers in parentheses refer to the list of references at the end tional Headquarters. Your comments will receive careful consideration at a meeting
of this standard. of the responsible technical committee, which you may attend.
D5424 − 23a
FIG. 4 Laser Extinction Beam
FIG. 5 Burner Holes
6.6.7 Supply compressed air to the burner, either bottled or
from a compressed air system. Filter the air supply sufficiently
so as to eliminate any contaminants that might affect the test
results.
6.6.8 Use air with a dew point no greater than 0 °C (32 °F),
as measured by a dew point measuring device.
6.6.9 Use CP grade propane (99 % pure), having a heat
content of approximately 50.8 MJ/kg (21.7 k Btu/lb)
(93.0 MJ ⁄m at 20 °C, 101 kPa), for the burner.
3 3
6.6.10 Use a propane flow rate of 220 cm /s 6 8 cm /s
3 3
(28 ft /h 6 1 ft /h) when corrected to standard temperature and
pressure (20 °C, 101 kPa). This propane flow will provide a
theoretical heat output of 20 kW (approximately
70 000 Btu ⁄h). The actual heat output is less, due to incomplete
combustion of the propane at the burner.
6.6.11 Use an air flow rate to the burner of 1280 cm /s 6
3 3 3
80 cm /s (163 ft /h 6 10 ft /h) when corrected to standard
temperature and pressure.
FIG. 6 Protocol B Cable Tray
6.7 Cable Mounting:
6.7.1 Protocol A—Fasten 2438 mm 6 10 mm (96-in. 6
0.5-in.) specimen lengths of finished cable in a single layer in
the tray by means of steel or copper wire, not larger than lengths with each cable vertical. Install as many specimens in
2.1 mm (14 AWG gauge) in cross section, at their upper and the tray as will fit, spaced ⁄2 cable diameter apart, to fill the
lower ends and at two other equally spaced points along their center 150 mm (6 in.) of the tray width.
D5424 − 23a
TABLE 1 Tray Loading for Circular Cables Smaller than 13 mm TABLE 2 Tray Loading for Cables 13 mm (0.5 in.) in Diameter and
(0.5 in.) in Diameter Larger
Number of Number of Cable Diameter, mm
Cable Diameter, mm Number of Cables
Cables in Bundles
in Tray
From But Less Than
From But Less Than
Each Bundle in Tray
13 15 11
11 13 3 7
15 19 9
9 11 3 8
19 21 8
6 9 3 10
21 26 7
5 6 7 9
26 28 6
3 5 19 8
28 39 5
0 3 19 13
39 52 4
52 73 3
73 120 2
6.7.1.1 Determine the number of specimen lengths for test
using Eq 1:
the range of the recording instrument. Use at least two neutral
N 5 @~4 × 25.4!/D#10.33 (1)
density filters of significantly different values, and also one for
where:
100 % transmission. Ensure that the transmittance values
N = number of cables (rounded up to the nearest whole
measured by the photometer, using neutral density filters, are
number), and
within 63 % of the specified value for each filter.
D = diameter of the cable, mm.
8.2 At the end of each test, investigate and correct any
6.7.2 Protocol B—Fasten 2438 mm 6 10 mm (96 in. 6
excessive departure from the zero line.
0.5 in.) specimen lengths of finished cable in the tray. Depend-
8.3 Perform a calibration of the flow rates of propane and air
ing upon the outside diameter of the individual cables, the test
from the burner before each continuous test series.
specimen is to be either an individual length or a bundle of
individual lengths. Center the specimens or specimen bundles 8.4 The recommended procedure for calibration of the
in a single layer between the side rails of the cable tray. Ensure propane gas flow rate is by measuring the heat release rate in
that the lower end of each specimen is no more than 100 mm the duct using Eq 3. Further details are given in X2.3.
(4 in.) above the bottom end of the cable tray. Attach each 0
A A
X 2 X
~ !
Δp
O O
2 2
individual specimen or bundle of specimens separately to each
q˙ 2 E × 1.10 × C × (3)
ŒF G F G
A
T 1.084 2 1.5 × X
e O
rung of the cable tray using one wrap of a copper or steel wire 2
tie not larger than 2.1 mm (14 AWG) in diameter.
where:
6.7.2.1 For cables smaller in diameter than 13 mm (0.5 in.),
q = rate of heat release, kW,
group the specimens into untwisted bundles (nominally circu-
1 1 1
C = orifice plate coefficient, in kg ⁄2 m ⁄2 K ⁄2 ,
lar) as shown in Table 1. Space the bundles ⁄2 bundle diameter
Δp = pressure drop across the orifice plate or bidirec-
apart on the cable tray as measured at the point of attachment
tional probe,
to the cable tray.
T = gas temperature at the orifice plate, K,
e
6.7.2.2 For cables 13 mm (0.5 in.) in diameter and larger,
E = net heat released for complete combustion, per unit
attach the individual specimens to the cable tray with spacings
of oxygen consumed, 13 100 kJ/kg O ,
A
of ⁄2 cable diameter, except do not exceed a spacing of 15 mm X = measured mole fraction of O in incoming air,
O 2
(0.6 in.). Table 2 shows the tray loading.
nondimensional, and
A
X = measured mole fraction of O in exhaust flow,
6.7.3 On flat cables, calculate the equivalent cable diameter
O 2
using Eq 2: nondimensional.
=
D 5 1.128 × ~T × W! (2)
9. Conditioning
where: 9.1 Prior to testing, condition the specimen for at least 3 h
in an atmosphere at a temperature of 23 °C 6 5 °C (73 °F) with
D = calculated equivalent cable diameter,
a relative humidity of less than 55 %. Test cables within 10 min
T = minor axis of the cable, and
of removal from such conditions if test room conditions differ
W = major axis of the cable.
from the preceding conditions.
7. Test Specimens
10. Procedure
7.1 Use multiple lengths of electrical or optical fiber cable
as test specimens.
10.1 Do not carry out the test if the wall temperature of the
chamber is below 5 °C (41 °F) or above 30 °C (86 °F).
7.2 The mounting of the specimen on the cable tray is
specified in 6.7.
10.2 Establish an initial volumetric flow rate of 0.65 m /s 6
3 3 3
0.05 m /s (23 ft /s 6 2 ft /s) through the duct. Calculate the
8. Calibration
volumetric flow rate of the gas in the duct from Eq A1.1 in
8.1 Prior to the start of each day of testing, verify the Annex A1 and reported as a function of time, starting 1 min
linearity of the photometer system by interrupting the light prior to the test. Do not change the flow rate once the initial
beam with multiple calibrated neutral density filters to cover flow rate is established.
D5424 − 23a
10.3 Position the prepared cable tray vertically inside the 10.11.4 For engineering information, record damage such as
enclosure with the open front of the cable tray facing the front blistering, or softening/melting of combustible material above
of the enclosure. Fix the cable tray firmly in position. the char.
10.12 Smoke Obscuration Measurements:
10.4 Start all recording and measuring devices before start-
10.12.1 Make continuous measurements of light obscura-
ing the ignition burner, to ensure they are stabilized.
tion by the smoke and volume flow rate in the exhaust duct.
10.5 Ignite the gas mixture in the burner and adjust the gas
10.12.2 From these measurements, and the equations in
flows to the values specified in 6.6.10 and 6.6.11. Position the
Annex A4, determine the rates and amounts of light obscuring
burner as indicated in 6.6.3 (Protocol A) or 6.6.4 (Protocol B).
smoke. These values together with the visual recordings
See Fig. 6 for the relative positions of the cable tray and burner
constitute the results from the test.
in the enclosure.
11. Calculation
10.6 Allow the burner flame to impinge on the specimen for
a continuous period of 20 min.
11.1 Equations for smoke release calculations are presented
in Annex A4. Considerations for heat release measurements
10.7 At 20 min, extinguish the burner flame, but allow the
(optional) are presented in Appendix X4, and the appropriate
cable fire (if any) to burn out.
equations for calculations are in Appendix X5. The choice of
10.8 Photograph or video record the cable tray and flame
the equations in Appendix X5 that the testing laboratory wishes
before and during the test. Include a clock, giving the time to
to use for the (optional) heat release calculations is up to the
the nearest 1 s, in all photographic records.
testing laboratory.
10.9 During the test, record the following events and the
12. Report
time when they occur:
12.1 Report the following information:
10.9.1 Ignition of the specimen,
12.1.1 Descriptive Information:
10.9.2 Position of flame front,
12.1.1.1 Name and address of the testing laboratory,
10.9.3 Melting and dripping,
12.1.1.2 Inside dimensions of the enclosure,
10.9.4 Occurrence of pool fire under the specimen,
12.1.1.3 Date and identification number of the report,
10.9.5 General description of the burning behavior,
12.1.1.4 Name and address of the test requester,
10.9.6 Time of afterburn, after extinguishing the propane,
12.1.1.5 Methods of sampling,
and
12.1.1.6 Name of product manufacturer or supplier, if
10.9.7 Any other event of special interest.
known,
12.1.1.7 Name or other identification marks and description
NOTE 3—It is possible for ignition of the cables to occur almost
of the product,
immediately after ignition of the burner. However, time to ignition of the
cables may be difficult to determine. 12.1.1.8 Density, or weight per unit surface, and total mass,
thickness of the main components in the product, and mass of
10.10 Conduct the procedure in duplicate on the number of
combustible portion of product, if known,
sets of specimens specified. Conduct each procedure (burn) on
12.1.1.9 Description of the samples,
untested cable specimens.
12.1.1.10 Conditioning of the specimens,
10.11 Evaluation of Damage:
12.1.1.11 Date of test, and
10.11.1 After burning has ceased, and after the cables and
12.1.1.12 Test number, Protocol (A or B), and any special
tray have cooled to room temperature, wipe the cables clean
remarks.
with a cloth, and determine cable damage.
12.1.2 Test Results (see also Appendixes).
12.1.3 Table of Mandatory Numerical Results Containing:
10.11.1.1 Protocol A—Determine the maximum height of
charred cable damage by measuring the blistering, char, and 12.1.3.1 Maximum char damage, m,
2 −1
12.1.3.2 Peak rate of smoke release, m s , and the appro-
other damage upward from the bottom of the vertical tray.
priate time that it occurred,
10.11.1.2 Protocol B—Determine the maximum height of
12.1.3.3 Total smoke released, m , and
charred cable damage by measuring the blistering, char, and
12.1.3.4 Time of afterburn, s.
other damage upward from the lower edge of the burner face.
12.1.4 Additional Table of Mandatory Numerical Results,
10.11.2 Determine the limit of charring by pressing against
Containing:
the cable surface with a sharp object. Where the surface of the
12.1.4.1 Total smoke release data after every minute, and
cable (outer jacket, if any) changes from a resilient surface to
12.1.4.2 Rate of smoke release data after every minute.
a brittle (crumbling) surface determines the limit of charring.
12.1.5 Mandatory Graphical Results:
Include distortion of the outer surface of the cable, such as
12.1.5.1 Plot of rate of smoke release versus time, and
blistering or melting, immediately above the char, in the
12.1.5.2 Plot of total smoke released versus time.
damage measurement.
10.11.3 Record the cable damage (char) to the nearest 12.2 Descriptive Results:
25 mm (1 in.). On cable constructions that do not have 12.2.1 Photographs or videotape, if available, of the fire
charring, define the limit for the affected portion as the point development, and
where the overall diameter is visibly reduced or increased. 12.2.2 All available information listed in 10.9.
D5424 − 23a
13. Precision and Bias 14. Keywords
13.1 Precision—The precision of this test method has not
14.1 cable; cable tray; carbon dioxide; carbon monoxide;
been determined. Results of a planned interlaboratory test
char; electrical cable; fire; fire-test response; flame; heat
series will be included when available.
release; heat release rate; ignition; optical density; optical fiber
cable; oxygen consumption calorimetry; smoke obscuration;
13.2 Bias—The true value of fire performance of electrical
or optical fiber cables can only be defined in terms of a test smoke release; smoke release rate; total smoke released; toxic
method. Within this limitation, this test method has no known gases
bias and can be accepted as a reference method.
ANNEXES
(Mandatory Information)
A1. CALCULATION OF VOLUMETRIC FLOW RATE
A1.1 The volumetric flow rate in m /s in the duct under
A = cross-sectional area of the duct at the location of the
standard conditions is calculated according to Eq A1.1, as
probe, m ,
follows:
Δ = differential pressure measured with the probe, Pa,
p
ρ = density of air, kg/m , at the reference temperature T ,
o o
2Δ T Δ
p o p
K,
V 5 C k AΠ5 20.1 kAΠ(A1.1)
F G F G
s V t
ρ T T
o T = duct gas temperature, K, and
T = the reference temperature, K.
o
where:
C = a suitable calibration factor for bidirectional probes
V
based upon air velocities in excess of 3.0 m/s (10 ft/s)
in a 0.4 m (16-in.) duct, nondimensional,
k = ratio of the average duct gas mass flow per unit area, as
t
determined by measuring the velocity and temperature
profiles across the stack, to the duct mass gas flow rate
per unit area, as determined by measuring the velocity
and temperature at the centerline where the bidirec-
tional probe is located during the test,
A2. DESIGN OF EXHAUST SYSTEM
A2.1 Hood and Exhaust Duct, Recommended Design: A2.1.3 If a laser beam is used, a suitable means of mounting
the beam together with the gas sampling probes is shown in
A2.1.1 Collect the combustion gases from the burning
Fig. A2.1.
specimen by means of a hood. A system is described in A2.1.2
which was tested in practice and proven to fulfill the specifi-
A2.1.4 An exhaust duct is connected with the plenum
cations given in the test method.
chamber. The inner diameter of the exhaust duct is 406 mm 6
A2.1.2 The hood is located above the room. The bottom
25 mm (16 in. 6 1 in.). To facilitate flow measurements, guide
dimensions of the hood are 2.44 m by 2.44 m (8 ft by 8 ft) (see
vanes, if needed, are located at both ends of the exhaust duct.
Fig. 1). The hood feeds into a cubical box/plenum having
Alternatively, the rectilinear part of the exhaust duct must have
914 mm 6 13 mm (36.0 in. 6 0.5 in.) as the dimension of each
such a length that a fully-developed flow profile is established
side. A maximum height of 1.8 m 6 0.05 m (5 ft 11 in. 6 2 in.),
at the point of measurement. The exhaust duct is connected to
to satisfy building constraints, is acceptable. Underneath the
an evacuation system.
hood, two baffle plates approximately 0.61 m by 0.61 m (2 ft
A2.1.5 Design the capacity of the evacuation system so as
by 2 ft) are located (see Fig. 1), to increase mixing of the
combustion gases. Design and manufacture the hood so that no to exhaust minimally all combustion gases leaving the speci-
−1
leakage exists. men. This requires an exhaust capacity of at least 2.7 kg s
D5424 − 23a
FIG. A2.1 Means of Mounting Laser Beam and Sampling Probe
3 −1
(about 8000 m h at standard atmospheric conditions) corre- A2.1.6 An alternative exhaust system design is acceptable if
sponding to a driving under pressure of about 2 kPa at the end it is shown to produce equivalent results. Equivalency is
of the duct. Provide a means to control the exhaust flow from
demonstrated by meeting the calibration requirements of Sec-
−1
about 0.5 kg s up to maximum flow as stated above during
tion 8. Exhaust system designs based on natural convection are
the test process. Ensure that the measurement system has
unacceptable.
sufficient sensitivity for measurement of low rates of heat
release. Mixing vanes in the duct are a means of solving the
problem if concentration gradients are found to exist.
A3. INSTRUMENTATION IN EXHAUST DUCT
A3.1 Volume Flow: isotherms to minimize conduction errors. Use an insulation
between the Chromel and Alumel wires that is stable to at least
A3.1.1 One technique for measuring the flow is a bidirec-
1100 °C (2000 °F). Ensure that the thermocouple does not
tional probe located at the centerline of the duct. The probe
disturb the flow pattern around the bidirectional probe.
shown in Fig. 2 consists of a stainless steel cylinder, 44 mm
(1.75 in.) long and with an inner diameter of 22 mm (0.875 in.).
A3.2 Smoke Obscuration:
The cylinder has a solid diaphragm in the center, dividing it
A3.2.1 One suitable light measuring system based on white
into two chambers. The pressure difference between the two
light has the following components: a lamp, plano convex
chambers is measured by a differential pressure transducer.
lenses, an aperture, a photocell, and an appropriate power
A3.1.2 Use a differential pressure transducer with an accu-
supply. Mount lenses, lamp, and photocell inside two housings
racy of at least 60.25 Pa (0.001 in.) of water and of the
located on the exhaust duct, diametrically opposite each other.
capacitance type. A suitable range of measurement is 0 Pa to
It has been found that a system consisting solely of a white
150 Pa.
light and a photocell, along the exhaust duct, across from each
other and at an angle to the vertical, is satisfactory in some
A3.1.3 Place one thermocouple 152 mm 6 25 mm (6 in. 6
cases.
1 in.) upstream from the bidirectional probe. Use an Inconel
sheathed 24 AWG gauge (0.51 mm (0.020 in.) in diameter) A3.2.1.1 Use a lamp of the incandescent filament type,
thermocouple, type K Chromel-Alumel. Place the thermo- which operates at a color temperature of 2900 °K 6 100 °K.
couple wire, within 13 mm (0.5 in.) of the bead, along expected Supply the lamp with stabilized direct current, stable within
D5424 − 23a
60.2 % (including temperature, short term and long term (2) Lamp—Osram Halo Stars: 64410: 6 V, 10 W, or
stability). Center the resultant light beam on the photocell. equivalent,
A3.2.1.2 Select the lens system such that the lens L ,
(3) Photocell—United Detector Technology: PIN 10 AP, or
according to Fig. 3, has a diameter, d, chosen with regard to the
equivalent, and
focal length, f, of L so that d/f ≤ 0.04.
2 (4) Voltage Supply—Gresham Lion Ltd: Model G × 012, or
A3.2.1.3 Place the aperture in the focus of lens L according
2 equivalent.
to Fig. 3.
A3.2.2.1 Design a system that is easily purged against soot
A3.2.1.4 Use a detector with a spectrally distributed re-
deposits. The use of holes in the periphery of the two housings
sponse according to the CIE photopic curve and linear within
is a means of achieving this objective.
5 % over an output range of at least 3.5 decades. Check this
linearity over the entire range of the instrument periodically
A3.2.3 An acceptable alternate system for measurements of
with calibrated optical filters.
smoke obscuration uses a laser beam. A 0.5 mW to 2.0 mW
helium-neon laser beam is projected across the exhaust duct.
A3.2.2 The system described as follows is an example of a
Couple the two halves of the device rigidly together (see Fig.
light measuring system that has been found satisfactory:
(1) Lenses—Plano convex: diameter 40 mm, focal length 4).
50 mm,
A4. SMOKE MEASUREMENT EQUATIONS
40,Re,3800 (A4.1)
A4.1 Mass Flow Rate Measurements:
NOTE A4.1—Symbols are explained in A4.3.
In many full scale fire test applications, duct diameter and
A4.1.1 There are primarily two techniques used to measure
flow rate are such that the Reynolds number is:
mass flow rate in the exhaust duct of full-scale fire tests.
Re.3800 (A4.2)
A4.1.2 The first technique measures mass flow rate by
In this case f(Re) can be taken as a constant (1.08), which
means of the pressure drop across, and temperature at, an
greatly simplifies the calculations.
orifice plate. If the test is conducted within a narrow range of
conditions, the orifice plate coefficient, C, is approximately A4.1.5 Mass Flow Rate Measurement Equations:
constant. It is possible to determine its value with a gas burner
A4.1.5.1 Pressure Drop Method (Eq A4.3):
calibration. However, if flow rates are varied during a test or if
Δp
temperature changes are considerable, take into account the
m˙ 5 C ׌ (A4.3)
F G
e
T
e
effect on C of the Reynolds number and of pressure at the
downstream side of the orifice plate. Information on such
A4.
...