ASTM F3538-22

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: F3538 − 22
Standard Test Method for
Measuring Heat Transmission Through Flame-Resistant
Materials for Clothing in Flame Exposure Using a
Cylindrical Specimen Holder
This standard is issued under the fixed designation F3538; 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 1.5 The values stated in SI units are to be regarded as
standard. The values given in parentheses are mathematical
1.1 This test method measures the thermal response of a
conversions to inch-pound units or other units commonly used
material or combination of materials using a combined
for thermal testing. If appropriate, round the non-SI units for
convective/radiant heat transmission apparatus consisting of an
convenience.
eccentric cylindrical test sensor. It can be used to estimate the
1.6 This standard does not purport to address all of the
non-steady state thermal transfer through flame-resistant ma-
safety concerns, if any, associated with its use. Fire testing is
terials used in clothing when subjected to a continuous,
inherently hazardous. Adequate safeguards for personnel and
combined convective and radiant heat exposure. The average
2 2
property shall be employed in conducting these tests. It is the
incident heat flux is 84 kW/m (2 cal/cm ·s), with durations up
responsibility of the user of this standard to establish appro-
to 30 s.
priate safety, health, and environmental practices and deter-
1.1.1 This test method is not applicable to materials that
mine the applicability of regulatory limitations prior to use.
melt, drip, or cause falling debris during the test.
1.7 This international standard was developed in accor-
NOTE 1—Because of the arrangement of the equipment, if materials
dance with internationally recognized principles on standard-
melt, drip, or cause falling debris during the test, the test result is invalid.
ization established in the Decision on Principles for the
1.2 Heat transmission through clothing is largely deter-
Development of International Standards, Guides and Recom-
minedbyitsthickness,includinganyairgaps.Theairgapscan
mendations issued by the World Trade Organization Technical
vary considerably in different areas of the human body. This
Barriers to Trade (TBT) Committee.
method provides a means of grading materials when tested
understandardtestconditionsandanairgapexistsbetweenthe
2. Referenced Documents
fabric and the sensor. During the exposure, fabric temperatures
2.1 ASTM Standards:
can exceed 400 °C.At these temperatures some fabrics are not
D123 Terminology Relating to Textiles
dimensionally stable and can shrink or stretch. The cylindrical
E457 Test Method for Measuring Heat-Transfer Rate Using
geometry used in this test method allows such motion to occur,
a Thermal Capacitance (Slug) Calorimeter
which will affect the time to achieve the end point of the test.
F1494 Terminology Relating to Protective Clothing
These effects are not demonstrated in planar geometry test
F2700 Test Method for Unsteady-State HeatTransfer Evalu-
methods such as Test Method F2700.
ation of Flame-Resistant Materials for Clothing with
1.3 This test method is used to measure and describe the
Continuous Heating
response of materials, products, or assemblies to heat under
2.2 AATCC Standard:
controlled conditions, but does not by itself incorporate all
AATCC LP1 Laboratory Procedure for Home Laundering:
factors required for fire hazard or fire risk assessment of the
Machine Washing
materials, products, or assemblies under actual fire conditions.
3. Terminology
1.4 The measurements obtained and observations noted
3.1 Definitions:
only apply to the particular material(s) tested using the
specified heat flux, flame distribution, and duration.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
ThistestmethodisunderthejurisdictionofASTMCommitteeF23onPersonal Standards volume information, refer to the standard’s Document Summary page on
Protective Clothing and Equipment and is the direct responsibility of Subcommittee the ASTM website.
F23.80 on Flame and Thermal. Available from American Association of Textile Chemists and Colorists
Current edition approved July 1, 2022. Published July 2022. DOI: 10.1520/ (AATCC), P.O. Box 12215, Research Triangle Park, NC 27709-2215, http://
F3538-22. www.aatcc.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F3538 − 22
3.1.1 breakopen, n—in testing thermal protective materials, along with the known thermophysical properties of copper, to
a material response evidenced by the formation of a hole in the determinetherespectivethermalenergypassedthroughthetest
test specimen during the thermal exposure that may result in specimen.
the exposure energy in direct contact with the heat sensor. 4.1.2 Acylinder heat transfer performance value (CHTP) of
the test specimen is calculated based on measurements from
3.1.2 charring, n—the formation of a carbonaceous residue
the calorimeter.
as the result of pyrolysis or incomplete combustion.
4.1.3 Observations of the thermal response of the specimen
3.1.3 cylinder heat transfer performance value (CHTP),
resulting from the exposure are optionally noted.
n—in testing of thermal protective materials with the use of a
5. Significance and Use
cylindrical specimen holder, the cumulative amount of thermal
energy identified by the intersection of the measured time-
5.1 This test method is intended for the determination of the
dependent heat transfer response through the subject material
cylinder heat transfer performance value of a flame-resistant
to a time-dependent, empirical performance curve, expressed
material or combination of materials when exposed to a
2 2
as a rating or value; J/cm (cal/cm ).
continuous and constant heat source. This is used to compare
materials used in flame-resistant clothing for workers when
3.1.4 embrittlement, n—the formation of a brittle residue as
exposed to combined convective and radiant thermal hazards.
a result of pyrolysis or incomplete combustion.
NOTE 3—Air movement at the face of the specimen and around the
3.1.5 heat flux, n—the thermal intensity indicated by the
calorimeter can affect the measured heat transferred due to forced
amountofenergytransmitteddividedbyareaandtime;kW/m
convective heat losses. Minimizing air movement around the specimen
(cal/cm ·s).
and test apparatus will aid in the repeatability of the results.
3.1.6 ignition, n—the initiation of combustion.
5.2 This test method maintains the specimen with and
without air gaps in a static, horizontal position and does not
3.1.7 melting, n—a material response evidenced by soften-
involve movement unless the test specimen naturally changes
ing of the polymer.
due to the thermal exposure.
3.1.8 response to heat exposure, n—in testing the thermal
5.3 This test method specifies a standardized 84 62kW/m
resistance of thermal protective materials, the observable
(2 6 0.05 cal/cm ·s) exposure condition. Different exposure
response of the material to the energy exposure as indicated by
conditions have the potential to produce different results. Use
breakopen, melting, dripping, charring, embrittlement,
of other exposure conditions that are representative of the
shrinkage, sticking, and ignition.
expected hazard are allowed but shall be reported with the
3.1.9 shrinkage,n—adecreaseinoneormoredimensionsof
results,alongwithadeterminationoftheexposureenergylevel
an object or material.
stability.
3.1.10 sticking, n—a material response evidenced by soft-
5.4 This test method does not predict skin burn injury from
ening and adherence of the material to the surface of itself or
the heat exposure.
another material.
5.5 This test method is similar toTest Method F2700 in that
3.1.11 unsteady-state heat transfer value, n—in testing of
it uses the same energy heat source, water-cooled shutter, data
thermal protective materials, a quantity expressed as the
acquisition, and measures the heat transfer through protective
time-dependent difference between the incident and exiting
clothing materials using a copper calorimeter.This test method
thermal energy values normal to and across two defined
differs from Test Method F2700 in the usage of an eccentric
parallel surfaces of an exposed thermal insulative material.
instrumented cylinder mounted horizontally that allows for the
thermal shrinkage of materials when tested.
3.2 For the definitions of protective clothing terms used in
this test method, refer to Terminology F1494, and for other
6. Apparatus and Materials
textile terms used in this test method, refer to Terminology
6.1 General Arrangement—The measurement apparatus
D123.
configuration consists of a combined convective and radiant
energy heat source, a water-cooled shutter for exposure
4. Summary of Test Method
control, a specimen and sensor support structure, a specimen
4.1 Atest specimen is wrapped around an instrumented test
holder assembly, a copper calorimeter sensor assembly, and a
cylinder that is horizontally positioned and exposed to a
data acquisition/analysis system. Automation of the apparatus
combined convective and radiant heat source with an exposure
for execution of the measurement procedure is allowed. The
2 2
heat flux of 84 62kW/m (2 6 0.05 cal/cm ·s).
general arrangement of the test apparatus configuration is
shown in Fig. 1.
NOTE 2—Other exposure heat flux values are allowed, however,
different exposure conditions have the potential to produce different
6.2 Gas Supply—Propane (commercial grade or better) or
results. The test facility must verify the stability of other exposure levels
methane (technical grade or better).
over the material’s exposure time interval (used to determine the heat
transfer performance value) and include this in the test results report.
6.3 Gas Flow Meter—Any gas flow meter or rotameter with
range to give a flow equivalent of at least 6 L(0.21 ft )/min air
4.1.1 The transfer of heat through the test specimen is
at standard conditions.
measured using a copper slug calorimeter with a convex
curvature. The change in temperature versus time is used, 6.4 Thermal Energy Sources:
F3538 − 22
FIG. 1 Apparatus Used to Measure Heat Transfer Performance of Textile Materials
FIG. 2 Convex Thermal Copper Calorimeter Heat Sensor
F3538 − 22
FIG. 3 Cylindrical Sensor Mounting Block
6.4.1 Two each, Meker or Fisher burners jetted for the 6.4.2.1 Use of a water-cooled housing for the quartz infra-
selected fuel gas (propane or methane) with a 38 mm (1.5 in.) red lamp bank is suggested. This helps to avoid heating
diametertoparearrangedsothatthebodies(topsection)donot adjacent mechanical components and to shield the operator
obstruct the quartz lamps and their flame profiles overlap. from the radiant energy.
Dimension tolerances are 65%.
NOTE 4—The exposure heat source incorporates two Meker or Fisher
6.4.2 A minimum of nine 500W T3 translucent quartz
burners and nine quartz infrared lamps.
infrared lamps, connected to a variable electrical power
6.5 Cylindrical Test Assembly:
controller, arranged as a linear array with 13 6 0.5 mm
center-to-center spacing set 125 6 10 mm from the specimen
NOTE 5—Tolerances are only provided for the mass of the thermal
surface.
copper slug sensor and the cylindrical sensor mounting block; all other
measurements are construction limits. Dimension units are mm (in.).
6.5.1 Thermal Copper Slug Sensor—A cylindrical-shaped
A 500-Watt T3 120V AC quartz infrared heat lamp, product number 21651-1
from Philips Lighting Company, has been used successfully in this application. disc, as shown in Fig. 2, shall be made of copper of at least
F3538 − 22
99 % purity, having the dimensions shown and a mass of 18 6 mounting block. The sensor is held into the recess of the
0.05 gbeforedrillingthedimpleforthethermocouple.Asingle cylinder using four straight pins, trimmed to a nominal length
ANSI Type J (Fe/Cu-Ni) thermocouple wire bead (0.254 mm of 5 mm, by placing them equidistant around the edge of the
wire diameter or finer, equivalent to 30 AWG) is installed as sensor so that the heads of the pins hold the sensor flush to the
shown in Fig. 3 (see Test Method E457 for information surface. The pinheads shall be trimmed so that they are flush
regarding slug calorimeters). Only the length attached to the with the surface of the cylinder (Fig. 4).
disc shall be bare. 6.5.4.1 Paint the exposed surface of the copper slug calo-
6.5.2 The thermocouple wire bead shall be installed in the rimeter with a thin coating of a flat black, high-temperature
calorimeter as shown in Fig. 2. spray paint with an absorptivity of 0.9 or greater. The painted
6.5.2.1 The thermocouple wire bead shall be bonded to the sensorshallbedriedandcuredaccordingtothemanufacturer’s
copper disk with a suitable HMP solder with a melting instructions before use and present a uniformly applied coating
temperature >280 °C. Only enough solder to fill the dimple (no visible thick spots or surface irregularities). In the absence
shall be used so that the mass of the calorimeter will be kept of manufacturer’s instructions, an external heat source, for
within the stated limits. example, an external heat lamp, shall be used to completely
drive off any remaining organic carriers in a freshly painted
NOTE 6—HMP solders consisting of 5 %Sb-95 %Pb (~307 °C melting
surface before use.
point) and 5 %Sb-93.5 %Pb-1.5 %Ag (~300 °C melting point) have been
found to be suitable. The 280 °C temperature minimum identified above
NOTE8—AbsorptivityofpaintedcalorimetersisdiscussedintheASTM
corresponds to the point where melting of the solder bond would be
Research Report, “ASTM Research Program on ElectricArc Test Method
experienced with a ~17 s exposure of an 84 kW/m heat flux to a prepared
Development to Evaluate Protective Clothing Fabric; ASTM F18.65.01
copper calorimeter with a surface area of 12.57 cm and a mass of 18.0 g.
Testing Group Report onArc TestingAnalysis of the F1959 Standard Test
A careful soldering technique is required to avoid “cold” solder joints
Method— Phase 1.”
(where the solder has not formed a suitable bond of the thermocouple to
6.5.5 Cylindrical Sensor and Specimen Holder—The cylin-
the copper disk).
drical sensor is mounted in an aluminum frame as shown in
6.5.3 Cylindrical Sensor Mounting Block—The calorimeter
Fig. 5. The aluminum frame has a thin aluminum rail running
is mounted in a cylindrical-shaped mounting block with the
along its length for clamping the test specimen during the
dimensions shown in Fig. 3. The thermal characteristics of the
exposure.
cylindrical sensor block shall be constructed from flame-
resistant material with a thermal conductivity value of ≤0.15 NOTE 9—The dimensions of the aluminum frame which holds the
cylindrical insulated mounting block are such that the device fits into the
W/m K, high temperature stability, and resistance to thermal
specimen holder support frame (Fig. 6) which has the same dimensions/
shockwhichwillnotcontributefueltothecombustionprocess.
specifications used in Test Method F2700 when used with the specimen
A cavity machined in the center of the cylindrical-shaped
holder gap filler (Fig. 7).
mounting block to accommodate the curved copper sensor and
6.5.6 Cylindrical Test Assembly Support Equipment (Sup-
an air gap as shown in Fig. 3. The cylindrical-shaped and
port Frame, Gap Filler, and Spacer):
insulated mounting block has an eccentric cylinder shape cut
6.5.6.1 Support Frame—A piece of steel 200 mm square,
into it to produce a 6.35 mm air gap between the back of the
3.0 mm thick, with a 100 mm square hole in its center (see Fig.
test specimen and the curved copper calorimeter.
6). Note that the overall dimensions of this will be specific to
NOTE 7—Marinite I structural insulation has been found to be a suitable
the test apparatus. The intention is to provide a repeatable
material for construction.
location for the sensor assembly placement.
6.5.4 The face of the curved copper calorimeter shall be 6.5.6.2 Gap Filler—A piece of steel 200 mm square,
flush with the surface of the cylindrical-shaped and insulated 6.4 mm thick, with a hole of the dimensions shown in Fig. 7.
FIG. 4 Cylindrical Sensor (copper disk mounted into recess of cylindrical sensor mounting block)
F3538 − 22
FIG. 5 Cylindrical Sensor and Specimen Holder
It is designed to sit inside the specimen holder support frame. 7. Hazards
Thecentercutoutissuchthatthecylinderspecimenholderwill
7.1 Perform the test in a hood to carry away combustion
fit inside.
products, smoke, and fumes. Shield the apparatus or turn off
6.5.6.3 Spacer—A piece of steel 150 mm square, 6.35 mm
the hood while running the test; turn the hood on to clear the
thick, with a 125 mm square hole in its center (see Fig. 8). The
fumes. Maintain an adequate separation between the burner
plate is used to raise the cylindrical specimen holder 6.35 mm
and combustible materials.
(0.25 in.) when testing the fabric in the spaced configuration.
7.2 The cylindrical test assembly is heated during testing.
This is done so the incident heat flux seen at the lower surface
Use protective gloves when handling these hot objects.
of the test specimen is the same as the incident heat flux set in
Section 9.
7.3 Use care when the specimen ignites or releases combus-
tible gases. Allow the sample to burn out or smother it if
6.6 Data Acquisition/Analysis System—A data acquisition/
necessary.
analysis system is required that is capable of recording the
calorimeter temperature response, calculating the resulting
7.4 Refer to Manufacturer’s Safety Data Sheets for infor-
thermal energy and ratio value, and determining the test
mation on handling, use, storage, and disposal of materials
endpoint by comparing the time-dependent thermal energy
used in this test method.
transfer reading to an empirical performance curve.
7.5 Refer to local codes for compliance on the installation
6.6.1 Thedataacquisitioncomponentshallhaveaminimum
and use of the selected fuel gas (propane or methane).
sampling rate of four samples per second for temperatures to
250 °C, with a minimum resolution of 0.1 °C and an accuracy
8. Sampling and Specimen Preparation
of 60.75 °C. It must be capable of making cold junction
8.1 Laboratory Sample—Select a minimum of a 1.0 m
corrections and converting the millivolt signals from the Type
sample size from the material to be tested. Individual test
J thermocouple to temperature (see NIST Monograph 175 or
specimens will be produced from this sample.
ASTM MNL 12 Manual on the Use of Thermocouples in
Temperature Measurement).
8.2 Laundering of Laboratory Sample:
8.2.1 For specimens submitted without explicit test launder-
6.7 Solvents, alcohol or petroleum solvent, for cleaning the
copper slug calorimeter. ing specifications, launder the laboratory sample for one wash
and dry cycle prior to conditioning. Use laundry conditions of
6.8 Paint,flatblackspraytype,withanabsorptivityvalueof
AATCC Laboratory Procedure 1 (1, V, A, i).
>0.90. See Note 8 for details.
8.2.1.1 Stitching the edges of the laboratory sample is
6.9 Cylindrical Test Assembly, see Figs. 9 and 10.
allowed to minimize unraveling of the sample material.
8.2.1.2 Restoring test specimens to a flat condition by
6.10 Shutter—A manual or computer-controlled shutter is
pressing is allowed.
used to block the energy from the burner (placed between the
8.2.1.3 If an alternative laundry procedure is employed,
cylindrical test assembly and the burner). Water-cooling is
recommended to minimize radiant heat transfer to other report the procedure used.
equipment components and to prevent thermal damage to the 8.2.2 For those materials that require cleaning other than
shutter itself. laundering, follow the manufacturer’s recommended practice
F3538 − 22
FIG. 5 Cylindrical Sensor and Specimen Holder (continued)
using one cleaning cycle followed by drying and note the 8.3 Test Specimens:
procedure used in the test report. 8.3.1 Spaced Configuration—Cut and identify test speci-
8.2.3 Materials designated by the manufacturer not to be mens from each swatch in the laboratory sample. Make each
laundered or cleaned shall be tested as received. test specimen 140 by 280 6 5 mm (5.5 by 11 6 ⁄8 in.). Five
F3538 − 22
angle from the horizontal so that the resulting flames converge
at a point immediately beneath the specimen.
9.2 Heat Flux Calibration—Calibrating the dual burner/
quartz lamp heat source heat flux value is an iterative process
that begins with the quartz infrared lamp assembly. After the
lamp assembly heat flux is fixed, the burners are adjusted to
2 2
obtain an 84 6 2 kW/m (2.0 6 0.05 cal/cm ·s) value for
testing. Several calibration passes of both heat source compo-
nents are typically required to establish the standard value for
testing within the specifications described below.
9.2.1 Set the output of the quartz infrared lamp assembly
afteraminimum15minwarm-upperiodto13 64kW/m (0.3
6 0.1 cal/cm ·s), as measured by an independent NIST
traceable Schmidt-Boelter or Gardon type radiant heat flux
sensor, positioned in the same geometry as the cylindrical
copper calorimeter sensor in the apparatus, using the lamp’s
variable power control.
9.2.2 Burner Gas Supply—Reduce the pressure on the gas
Overall dimensions are specific to test apparatus used. Dimensional units are
supply to about 55 kPa (8 psig) for proper flame adjustment
mm (in.).
and remove the Schmidt-Boelter or Gardon type radiant heat
FIG. 6 Support Frame
flux sensor from the specimen holder (it is used only to
calibrate the quartz lamp assembly).
9.2.3 With the quartz lamp bank on (heat flux output set to
each shall be cut with the long dimensions parallel to the warp
13 64kW/m ), start the two burners at a low gas flow rate
yarns and five wit
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