ASTM F1959/F1959M-24a

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: F1959/F1959M − 24a
Standard Test Method for
Determining the Arc Rating of Materials for Clothing
This standard is issued under the fixed designation F1959/F1959M; 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 responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
1.1 This test method is used to determine the arc rating of
mine the applicability of regulatory limitations prior to use.
materials intended for use as flame resistant clothing for
For specific precautions, see Section 7.
workers exposed to electric arcs that would generate heat flux
2 2 1.9 This international standard was developed in accor-
rates of approximately 2100 kW/m [50 cal/cm s] using an
dance with internationally recognized principles on standard-
open air arc.
ization established in the Decision on Principles for the
1.2 This test method will determine the arc rating of
Development of International Standards, Guides and Recom-
materials which meet the following requirements: less than
mendations issued by the World Trade Organization Technical
150 mm [6 in.] char length and less than 2 s afterflame when
Barriers to Trade (TBT) Committee.
tested in accordance with Test Method D6413.
1.2.1 It is not the intent of this test method to evaluate non 2. Referenced Documents
flame-resistant materials.
2.1 ASTM Standards:
1.3 The materials used in this test method are in the form of D123 Terminology Relating to Textiles
flat specimens.
D1776/D1776M Practice for Conditioning and Testing Tex-
tiles
1.4 This test method shall be used to measure and describe
D3776/D3776M Test Methods for Mass Per Unit Area
the properties of materials, products, or assemblies in response
(Weight) of Fabric
to convective and radiant energy generated by an electric arc
D4391 Terminology Relating to The Burning Behavior of
under controlled laboratory conditions.
Textiles
1.5 The values stated in SI units shall be regarded as
D6413 Test Method for Flame Resistance of Textiles (Ver-
standard except as noted. Within the text, alternate units are
tical Test)
shown in brackets. The values stated in each system may not be
E457 Test Method for Measuring Heat-Transfer Rate Using
exact equivalents therefore alternate systems must be used
a Thermal Capacitance (Slug) Calorimeter
independently of the other. Combining values from the systems
F1494 Terminology Relating to Protective Clothing
described in the text may result in nonconformance with the
F1506 Performance Specification for Flame Resistant and
method.
Electric Arc Rated Protective Clothing Worn by Workers
1.6 This test method does not apply to electrical contact or Exposed to Flames and Electric Arcs
electrical shock hazards.
2.2 ANSI/IEEE Standard:
Standard Dictionary of Electrical and Electronics Terms
1.7 This standard shall not be used to describe or appraise
2.3 AATCC Standard:
the fire hazard or fire risk of materials, products, or assemblies
AATCC Laboratory Procedure 1-2021 Home Laundering:
under actual fire conditions. However, results of this test may
Machine Washing
be used as elements of a fire assessment which takes into
account all of the factors which are pertinent to an assessment
3. Terminology
of the fire hazard of a particular end use.
3.1 Definitions:
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
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
This test method is under the jurisdiction of ASTM Committee F18 on Standards volume information, refer to the standard’s Document Summary page on
Electrical Protective Equipment for Workers and is the direct responsibility of the ASTM website.
Subcommittee F18.65 on Wearing Apparel. Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
Current edition approved March 1, 2024. Published March 2024. Originally 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331.
approved in 1997. Last previous edition approved in 2024 as F1959/F1959M – 24. Technical Manual of the American Association of Textile Chemists and
DOI: 10.1520/F1959_F1959M-24A. Colorists.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1959/F1959M − 24a
3.1.1 ablation, n—in electrical arc testing, a physical re- through the tested specimen is predicted to cause the onset of
sponse evidenced by significant erosion or the formation of one a second-degree skin burn injury based on the Stoll curve,
2 2
or more large holes in a layer of a multilayer system. kJ/m [cal/cm ].
2 2
3.1.8.1 Discussion—This is the value in kJ/m [cal ⁄cm ]
3.1.1.1 Discussion—Any layer in a specimen (other than the
determined by use of logistic regression analysis representing
innermost layer) is considered to exhibit ablation when the
2 2
the energy at which breakopen of the layer occurred.
material removal or any hole is at least 16 cm [2.5 in. ] in area
or at least 8 cm [3.1 in.] in length in any dimension. Single 3.1.9 arc voltage, n—voltage across the gap caused by the
threads across the opening or hole do not reduce the size of the
current flowing through the resistance created by the arc gap,
hole for the purposes of this test method. Ablation in one or V.
more layers of material in a mulitlayer system may remove
3.1.10 asymmetrical arc current, n—the total arc current
energy from the specimen (see 11.3.7).
produced during closure; it includes a direct component and a
symmetrical component, A.
3.1.2 ablation response energy (E ), n—the incident energy
ab
on a multilayer system that results in a 50 % probability of the
3.1.11 blowout, n—the extinguishing of the arc caused by a
physical response of ablation. magnetic field.
3.1.12 breakopen, n—in electric arc testing, a material
3.1.3 arc duration, n—time duration of the arc, s.
response evidenced by the formation of one or more holes in
3.1.4 arc energy, vi dt, n—sum of the instantaneous arc
the material which may allow thermal energy to pass through
voltage values multiplied by the instantaneous arc current
the material.
values multiplied by the incremental time values during the
3.1.12.1 Discussion—The specimen is considered to exhibit
arc, J.
2 2
breakopen when any hole is at least 1.6 cm [0.5 in. ] in area
3.1.5 arc gap, n—distance between the arc electrodes, mm
or at least 2.5 cm [1.0 in.] in any dimension. Single threads
[in.]. across the opening or hole do not reduce the size of the hole for
the purposes of this test method. In multiple layer specimens of
3.1.6 arc rating, n—value attributed to materials that de-
flame resistant material, all the layers must breakopen to meet
scribes their performance to exposure to an electrical arc
the definition. In multiple layer specimens, if some of the
discharge.
layers are ignitable, breakopen occurs when these layers are
3.1.6.1 Discussion—The arc rating is expressed in kJ/m
exposed.
[cal/cm ] and is derived from the determined value of ATPV or
3.1.13 breakopen threshold energy (E ), n—the incident
BT
E (should a material system exhibit a breakopen response
BT
energy on a material or material system that results in a 50 %
below the ATPV value) or the arc rating limit. It can be
probability of breakopen.
expressed in short form as either ATPV, E or AR .
BT Lim
2 2
3.1.13.1 Discussion—This is the value in J/cm [cal ⁄cm ]
3.1.7 Arc Rating Limit (AR ), n—the maximum arc ther-
Lim
determined by use of logistic regression analysis representing
mal energy protection that has been assigned to the product
the energy at which breakopen of the layer occurred.
based on the manufacturer’s specifications after verification
3.1.14 charring, n—the formation of carbonaceous residue
with testing or limits of detection of the test method.
as the result of pyrolysis or incomplete combustion.
3.1.7.1 Discussion—In electrical arc panel testing of fabrics,
3.1.15 dimensional change, n—in testing flame resistant
the AR may be used when the practical limit of the
Lim
clothing, a material response evidenced by change in specimen
equipment has been reached and the distribution of the data
size, this may be positive or negative.
does not fulfill the data point distribution requirements for
3.1.15.1 Discussion—In arc testing, dimensional change is
completion of the logistic regression analysis. The numerical
typically described in relative terms by observation after the
value of AR assigned from the data set in this case is the
Lim
arc test exposure (for example, “moderate shrinkage” or “slight
value where all specimen responses are below the Stoll curve
expansion”).
and without breakopen.
3.1.16 dripping, n—in testing flame-resistant clothing, a
3.1.7.2 Discussion—This rating may also be set to any value
material response evidenced by flowing of a specimen’s
less than the ATPV/EBT to allow for variation in design,
material of composition.
manufacture, or test laboratory results. For example, if a fabric
is tested multiple times, the lowest ATPV/EBT or a lower 3.1.17 embrittlement, n—the formation of a brittle residue
as the result of pyrolysis or incomplete combustion.
rating to account for variability may be assigned as agreed
upon by the manufacturer and the lab, which is less than the arc
rating determined in testing. 5
Derived from: Stoll, A. M. and Chianta, M. A., “Method and Rating System for
Evaluations of Thermal Protection,” Aerospace Medicine, Vol 40, 1969, pp.
3.1.8 arc thermal performance value (ATPV), n—the inci-
1232-1238 and Stoll, A. M. and Chianta, M. A., “Heat Transfer through Fabrics as
dent energy on a material or a multilayer system of materials
Related to Thermal Injury,” Transactions—New York Academy of Sciences, Vol 33
that results in a 50 % probability that sufficient heat transfer (7), Nov. 1971, pp. 649-670.
F1959/F1959M − 24a
3.1.18 fabric weight, n—in arc testing, the measured value highest incident energy with a negative result is greater than
of a specific sample of the fabric mass per unit area expressed the lowest incident energy with a positive result.
in grams per square meter (ounces per square yard), that is used
3.1.29 peak arc current, n—maximum value of the AC arc
to generate the fabric’s arc rating.
current, A.
3.1.19 fabric weight, actual, n—the measured value of a
3.1.30 RMS arc current, n—root mean square of the AC arc
sample of fabric mass per unit area expressed in grams per
current, A.
square meter (ounces per square yard), from a lot of fabric as
3.1.31 shrinkage, n—in testing flame resistant clothing, a
produced by the fabric manufacturer; this measurement is done
material response evidenced by reduction in specimen size.
in accordance with Test Methods D3776/D3776M before
washing and after conditioning in accordance with Test
3.1.32 Stoll curve , n—an empirical predicted second-
Method D1776/D1776M.
degree skin burn injury model, also commonly referred to as
3.1.20 fabric weight, arc test, n—the measured value of a the Stoll Response.
specific sample of the fabric mass per unit area expressed in
3.1.33 X/R ratio—the ratio of system inductive reactance to
grams per square meter (ounces per square yard), that is used
resistance. It is proportional to the L/R ratio of time constant,
to generate the fabric’s arc rating according to Test Method
and is, therefore, indicative of the rate of decay of any DC
F1959/F1959M.
offset. A large X/R ratio corresponds to a large time constant
3.1.20.1 Discussion—This weight is sometimes referred to
and a slow rate of decay.
as "AAD" or "Average Areal Density" on arc test reports.
3.2 For definitions of other textile terms used in this test
Before recording this weight, fabric is prepared in accordance
method, refer to Terminologies D123, D4391, and F1494.
with the preparation instructions of Test Method F1959/
F1959M without conditioning in accordance with Test Method
4. Summary of Test Method
D1776/D1776M. Weight of the prepared fabric is required to
be recorded prior to arc testing.
4.1 This test method determines the heat transport response
3.1.21 fabric weight, nominal, n—the target mass per unit through a material, fabric, or fabric system when exposed to
area expressed in grams per square meter (ounces per square
the heat energy from an electric arc. This heat transport
yard), for all production fabrics. response is assessed versus the Stoll curve.
3.1.21.1 Discussion—This is the official published weight
4.1.1 During this procedure, the amount of heat energy
and should not change once established for each unique fabric
transferred by the tested material is measured during and after
identifier. Manufacturers may have different acceptable vari-
exposure to an electric arc.
ances to the published weights.
4.1.1.1 The thermal energy exposure and heat transport
response of test specimens are measured with copper slug
3.1.22 heatflux, n—the thermal intensity indicated by the
calorimeters. The change in temperature versus time is used,
amount of energy transmitted divided by area and time
2 2
along with the known thermo-physical properties of copper to
kW/m [cal ⁄cm s].
determine the respective heat energies delivered to and through
3.1.23 ignition, n—the initiation of flaming and combustion.
the specimens.
3.1.24 incident energy monitoring sensors, n—sensors
4.2 Material performance for this procedure is determined
mounted on each side of the panel, using the calorimeters
from the amount of heat transferred by and through the tested
described in 6.5, not covered by test material, used to measure
material.
incident energy.
4.3 Heat transfer data determined by this test method is the
3.1.25 incident energy (E ), n—the total heat energy re-
i
basis of the arc rating for the material.
ceived at the surface of the panel as a direct result of an electric
arc.
4.3.1 The arc rating determined by this test method is the
amount of energy that predicts a 50 % probability of second-
3.1.26 material response, n—material response to an elec-
degree burn as determined by the Stoll Curve or breakopen
tric arc is indicated by the following terms: breakopen, melting,
(should the specimen exhibit breakopen before the skin burn
dripping, charring, embrittlement, shrinkage, dimensional
injury prediction is reached. The arc rating may also be
change, and ignition.
expressed as an arc rating limit (AR ) based on limits of the
Lim
3.1.27 melting, n—in testing flame resistant clothing, a
test apparatus or material performance. The AR is allowed
Lim
material response evidenced by softening of the material.
to be a derated limit set by the manufacturer.
3.1.28 mix zone, n—in arc testing, the range of incident
4.4 Material response shall be further described by record-
energies, which can result in either a positive or negative
ing the observed effects of the electric arc exposure on the
outcome for predicted second-degree burn injury or breakopen;
specimens using the terms in 11.1.8.
the low value of the range begins with the lowest incident
energy indicating a positive result, and the high value of the
5. Significance and Use
range is the highest incident energy indicating a negative
result.
5.1 This test method is intended for the determination of the
3.1.28.1 Discussion—A mix zone is established when the arc rating of a material, or a combination of materials.
F1959/F1959M − 24a
5.1.1 Because of the variability of the arc exposure, differ- and a diameter to accommodate the bare thermocouple tip. The
ent heat transmission values may be observed at individual tip of the thermocouple shall be bare for the full length inside
sensors. Evaluate the results of each sensor in accordance with the copper disc. Copper filler material may be used to mechani-
Section 12. cally secure the thermocouple tip in place, soldering of the
thermocouple is not permitted. The thermocouple wires shall
5.2 This test method maintains the specimen in a static,
be separated immediately upon exiting the copper disc. (See
vertical position and does not involve movement except that
Test Method E457 for information regarding slug calorim-
resulting from the exposure.
eters.)
5.3 This test method specifies a standard set of arc expo-
6.2.3 The insulating material in which the calorimeter disc
sures performed under controlled laboratory conditions. Dif-
is inserted shall have a thermal conductivity not exceeding
ferent exposure conditions have the potential to produce
0.23 W ⁄mK at temperatures up to 500 °C (1). Due to the
different results. In addition to the standard set of exposure
mechanical properties of the material, the board shall be 1.3 cm
conditions, other conditions representative of the expected
[0.5 in.] or greater in thickness. The shape of the surrounding
hazard may be used and shall be documented in the reporting
board may be circular or rectangular of any practical size but
of the testing results.
shall extend a minimum of 5 mm past the edge of the copper
disk.
6. Apparatus
6.2.4 A circular cavity is machined in the front of the
6.1 Test Apparatus for Determining Arc Rating Using Three
insulating material to accommodate the copper disc so that the
Two-Sensor Panels and Monitor Sensors—The test apparatus
surface of the copper disc will be flush with the surface of the
shall consist of three two-sensor panels, monitor sensors,
surrounding surface. The supporting shoulder shall be equal to
supply bus and electrodes, electrical supply, test controller, and
or greater than 1.0 mm, but not be more than 1.6 mm, that is,
data acquisition system.
the inner diameter shall be not less than 36 mm and not greater
6.2 Calorimeter (Sensor) Construction:
than 38 mm. See Fig. 2 and Notes 3-8. The cavity, when new,
6.2.1 The calorimeter shall be constructed from electrical
shall have a diameter which provides friction fit of the copper
grade copper with purity greater than 99.9 %, UNS C11000.
disc. Additional support shall be provided by four stainless
The copper disc shall have a thickness of 1.6 mm 6 0.1 mm,
steel shirt pins with a flat stainless steel head, cut to a practical
a diameter of 40 mm 6 0.1 mm, and a mass of 18 g 6 1 g. The
length (for example, 5 mm) and hammered straight or slightly
thickness, diameter, and mass of each copper disc shall be
inclined into the board, sitting half on the disc and half on the
measured to determine the actual response coefficient for each
board.
calorimeter that is used in heat capacity calculations. In the
6.3 Two-Sensor Panel Test Assembly—Each two-sensor
case of a group of copper discs having an average mass/area
panel shall consist of two sensors, an insulating board, a
ratio within 60.008 g/cm , the average value for the group of
support frame for the fabric, a fabric clamping system and two
calorimeters may be used.
monitor sensors.
6.2.2 A welded tip type K (NiCr-NiAl) thermocouple hav-
ing a cross-sectional area of 0.05 mm (No. 30 AWG) or 6.3.1 The insulating board shall be 20 cm × 55 cm 6 1.3 cm
equivalent, but not larger, shall be used to construct the [8 in. × 21.5 in. 6 0.5 in.] made of electrical and heat-resistant
calorimeter. The thermocouple shall be installed inside the hole material having a thermal conductivity not exceeding
of the copper disc as shown in Fig. 1. The hole shall be drilled 0.30 W ⁄mK at temperatures up to 200 °C. The front edges of
at the center of the copper disc to a depth of 1.3 mm 6 0.1 mm the board shall be rounded to have a smooth edge as to allow
Item:
1 Copper disc, diameter: 40 mm ± 0.1 mm, thickness: 1.6 mm ± 0.1 mm, weight: 18 g ± 1 g
2 Hole for thermocouple, diameter to fit thermocouple tip, depth: 1.3 mm ± 0.1 mm
3 Type K thermocouple wire, welded tip fully inserted in the hole
4 Copper filler material peened to secure and maintain full contact of thermocouple wire to disc
FIG. 1 Example of Calorimeter Construction
F1959/F1959M − 24a
Item:
1 Calcium silicate insulating material, minimum 1.3 cm thick
2 40 mm Copper disc as assembled in Fig. 1
3 Type K thermocouple, 30 AWG
4 Supporting shoulder for disc, 1 mm to 1.6 mm wide, depth of 1.6 mm for disc
5 Copper disc fully inserted into the insulating board
6 High temperature insulating board as protective heat shield for monitor sensors ONLY, 40.5 mm to 42 mm hole, 3 mm thick
7 Stainless steel pins (3-5 may be used to secure the disc in place)
FIG. 2 Calorimeter and Thermocouple Installation Detail
the fabric to slide. Two sensors (see Fig. 2) shall be inserted the insulating board. In this case, the insulating board shall
into the front board placed on the vertical center line of the meet the material property requirements of 6.2.3 and the
insulated board, as shown in Fig. 3, and flush with the surface. copper discs shall be mounted and fitted into the insulating
Alternatively, two copper discs can be mounted directly into board according to the requirements of 6.2.4. The two-sensor
Item:
1 Calorimeter
2 Two sensor panel
FIG. 3 Two Sensor Panel
F1959/F1959M − 24a
panel shall be constructed to protect the two thermocouple 6.3.4 Emissivity Primer—The exposed surface of the copper
wires fully from the side and back from the influence (for calorimeters shall be painted with a thin coating of a flat black,
example, heat, contamination) of and eventual damage caused high temperature spray paint with an emissivity of >0.9. The
by the arc event. painted sensor shall be dried before use and present a uni-
6.3.2 A support frame shall be used to hold the panel formly applied coating (no visual thick spots or surface
perpendicular to the electrodes and maintain the test specimen irregularities).
at the correct distance and height. An example of a support
6.3.4.1 An external heat source such as an external heat
frame is shown in Fig. 4. Alternate insulating material may be lamp or heat gun may be used to dry the freshly painted
used for the panel construction not in contact with the
surface.
calorimeter. The material for the support frame may be any
6.3.4.2 An evaluation of the emissivity of the painted
suitable, structurally-stable and flame-resistant material.
calorimeters used in this test method is available from ASTM;
6.3.3 Monitor Sensors—Monitor sensors are located on
“ASTM Research Program on Electric Arc Test Method
each side of the two-sensor panel to measure the incident
Development to Evaluate Protective Clothing Fabric; ASTM
energy. The size and support for the monitor sensor can be
F18.65.01 Testing Group Report on Arc Testing Analysis of the
arranged to fit the panel construction but shall be constructed to
F1959 Standard Test Method—Phase 1.”
protect the copper disc fully, from the side and back, from the
6.3.5 Clamping Mechanism—Each two-sensor panel shall
influence (for example, heat, contamination) of and eventual
have four clamps (one on each side) which hold the specimen
damage caused by the arc event.
in place, an example of a system is shown in Fig. 4 and Fig. 5.
6.3.3.1 To prevent damage of the insulating material sur-
The clamp system shall cover the full perimeter of the panel
rounding the copper disc from the intense heat of the arc, an
and allow the material to shrink during arc exposure. Each
additional thin heat shield (refractory sheet) may be used to
clamp shall apply between 4.4 N and 6.7 N [1 lbf and 1.5 lbf]
protect the insulating material of the sensor. This sheet shall be
to secure the material to the edges of the two-sensor panel.
electrically insulating and not exceed 3 mm [ ⁄8 in.] thickness.
Other means of mounting, which meet the above objectives,
may also be employed.
NOTE 1—The use of a heat shield helps to minimize damage to the
surface of the insulating material. Calcium silicate insulating material is
NOTE 2—A spring scale has been found to be a satisfactory way to
used in the sensor construction because it has low thermal conductivity,
measure the clamping force. The clamp force is measured just at the
has a lower melting temperature, and may be damaged when directly
instant the mechanism starts to move from the panel.
exposed to the arc.
NOTE 3—An example of an insulating board material for mount of
calorimeters is a calcium silicate insulating material. Other materials
6.3.3.2 The heat shield covering the insulating material of
meeting the criteria may be used.
the sensor shall have a hole slightly larger in diameter (not
NOTE 4—An example of insulating board material for panel construc-
more than 2 mm larger) than the calorimeter and shall be
tion and clamps is a calcium silicate insulating material. Other materials
centered over the calorimeter as shown in Fig. 2. The thin
meeting the criteria may be used.
shield may be fixed by screws onto the surface of the sensor, no
NOTE 5—“Friction fit” means that when the disc has been put in place
closer than 1.5 cm from the copper disc. and then the front board turned upside down, the disc will not fall out.
Item:
1 Panel structural support frame, see 6.3
2 Support table or base, adjustable to allow fine adjustment of front panel
3 Clamping Mechanism, see 6.3.5, 4 sides
4 Incident energy monitors (two each for each panel, see Fig. 6 for positioning)
5 Two sensors mounted in the panel
6 Stainless steel electrodes
FIG. 4 Example of Two Sensor Panel Positioning with Stainless Steel Electrodes
F1959/F1959M − 24a
Item:
1 Support frame
2 Hinged fabric clamping mechanism
3 Typical spring clamp arrangement, springs in compression or
tension, alternate methods which meet the above objectives,
may also be employed
4 Springs to provide 4.4 N to 6.7 N of force
5 Rounded edges on clamp piece, r = 12 mm
6 Two-sensor panel, rounded edges, r = 12 mm
7 Calorimeter
FIG. 5 Two Sensor Panel Clamping Mechanism
NOTE 6—A friction fit of the copper disc into the insulating board is to
6.4.1 One monitor sensor shall be positioned on each side of
prevent hot gases from heating up the side or entering behind the disc and
a two-sensor panel. The monitor sensor shall be positioned
deteriorating the sides of the cavity
perpendicular to radius drawn from the center line of the
NOTE 7—To minimize the contact area between the shoulder of the
electrodes to the center of the monitor sensor. The angle α
ledge and the backside of the copper disc, the shoulder of the ledge can be
machined slightly angled inwards (for example, by a few degrees), that is,
between the radius drawn to the center of the monitor sensors
away from the backside of the copper disc.
and the radius drawn to the center line of the panel surface shall
NOTE 8—After having verified that the disc has been mounted flush
adjust to the range, as indicated in Table 1, from the center line
with the surface of the surrounding insulating board and has the required
of the arc electrodes (see Fig. 6). Distances r and r have been
friction fit to the insulating board, the disc can be secured in place by pins
1 2
(for example, at least 3 pins) equally spaced around the circumference of
found to be practical, thus shall be selected for different
the disc.
incident energy exposures (see Table 1).
NOTE 9—A high temperature refractory sheet should be 3 mm or ⁄8 in.
6.4.2 The actual distance of the monitor sensors and two-
thick.
sensor panels (r , r ) shall be measured and the value used to
6.4 Arrangement of the Two-Sensor Panels and Monitor 1 2
determine the multiplier for the incident energy calculation in
Sensors—The configuration of three panels shall be used for
12.3.1. The actual distance of each panel and monitor sensor
each test and the panels shall be spaced at 120°, having a
shall be measured to a precision of 62 mm. The multiplier
distance as indicated in Table 1 and shown in Fig. 6.
TABLE 1 Positioning of Two-sensor Panels and Monitor Sensors depending on Incident Energy Exposure
2 2 2
0 kJ ⁄m to 2300 kJ ⁄m >1675 kJ/m
Target incident energy
2 2 2
0 cal ⁄cm to 55 cal/cm >40 cal/cm
Position of two-sensor panels 305 mm ± 5 mm 305 mm ± 5 mm
Monitor sensors: Position 1 Position 2
Distance between vertical centre line of electrodes and r r
1 2
centre of monitor sensor surface 340 mm ± 5 mm 410 mm ± 5 mm
Angle between perpendicular line to panel surface and
35° -0°/+5° 35° -0°/+5°
perpendicular line to monitor sensor surface
F1959/F1959M − 24a
NOTE 1—Drawing showing alternate positions of incident energy monitor sensors; see Table 1 for distance of r and r based on range on incident
1 2
energy.
FIG. 6 Arrangement of Three Two-Sensor Panels with Monitor Sensors
factor shall be the square of the ratio of the actual distance of 6.6 Electric Supply—The electric supply should be suffi-
the monitor sensor divided by the actual distance of the cient to allow for the discharge of an electric arc with a gap of
two-sensor panel to which the monitor is positioned. Example:
up to 305 mm [12 in.] with alternating arc current of 8 kA 6
When having the two-sensor panel at 305 mm and the incident
0.5 kA, and with arc duration of 1 s from a 60 Hz or 50 Hz
energy monitors at 340 mm, the incident correction factor is
supply. The X/R ratio of the test circuit shall be such that the
(340/305) = 1.24.
test current contains a DC component resulting in the first peak
of the test current having a magnitude of 2.3 times the
6.5 Supply Bus and Electrodes—The supply bus and arc
symmetrical RMS value.
electrodes shall be part of structural arrangement, which is
designed to reduce the electromagnetic forces on the arc and
6.6.1 The voltage shall be sufficient to maintain the arc for
thus centers the rotation of the arc along the center line
the whole duration of the test. An open circuit voltage of at
between the electrodes. A typical structural arrangement that
least 2000 V has proven to be sufficient.
includes a cage with six conductive tubes and arc electrodes is
6.6.2 In order to be able to test materials with arc ratings up
shown in Fig. 7. The arc shall be in a vertical position as 2 2
to 4200 kJ/m [100 cal/cm ], the electric supply shall be
shown. Power to the cage may be from the top or the bottom
sufficient to allow for arc duration of over 2 s. If the electric
depending on the design adopted by the laboratory.
supply is only capable of generating arcs of shorter periods,
6.5.1 Structural Cage Arrangement—The structural cage
testing will be limited to only materials with lower arc rating.
arrangement shall be made of conductive tubes (for example,
metallic tubes, such as aluminum or steel tubes). The diameter 6.7 Test Circuit Control—The make switch shall be capable
of the cage shall be between 2.0 m and 2.5 m. The height of the of point on wave closing within 60.5 ms from test to test such
cage shall be at least 3 m.
that the closing angle will produce maximum asymmetrical
current with an X/R ratio of the test circuit as stated in 6.6.
NOTE 10—Based on modelling, the best performance of the cage to
keep the arc in the centerline of the arc gap may be obtained by the
6.8 Data Acquisition System—The system shall be capable
following conditions: (1) the greater the ratio between the height and the
of recording voltage, current, and sufficient calorimeter outputs
diameter of the cage and (2) having the mid-point of the electrode gap in
as required by the test.
the middle of the height of the cage.
6.8.1 The temperature waveform data (calorimeter outputs)
6.5.2 Electrodes—The electrodes shall be stainless steel
shall be acquired at a minimum sampling rate of 100 samples
(Alloy Type 303 or Type 304) rod of 19 mm [0.75 in.]
per second per calorimeter. The acquisition system shall be
diameter.
able to record temperatures up to 500 °C with an accuracy of at
6.5.3 Fuse Wire—A fuse wire, connecting the ends of
opposing electrode tips, is used to initiate the arc. This wire is least 62 % (This does not include the accuracy of the
calorimeter). The temperature shall be recorded with a resolu-
consumed during the test. The fuse wire shall be a copper wire
with a diameter not greater than 0.5 mm [0.02 in.]. tion of 0.1 °C for calculation of the energy.
F1959/F1959M − 24a
7. Precautions
7.1 The test apparatus discharges large amounts of energy.
In addition, the electric arc produces very intense light. Care
should be taken to protect personnel working in the area.
Workers should be behind protective barriers or at a safe
distance to prevent electrocution and contact with molten
metal. Workers wishing to directly view the test should use
very heavily tinted glasses such as ANSI/ASC Filter Shade 12
welding glasses. If the test is conducted indoors there shall be
a means to ventilate the area to carry away combustion
products, smoke, and fumes. Air currents can disturb the arc
reducing the heat flux at the surface of any of the calorimeters.
Non-combustible materials suitable for the test area should
shield the test apparatus. Outdoor tests shall be conducted in a
manner appropriate to prevent exposure of the test specimen to
moisture and wind (the elements). The leads to the test
apparatus should be positioned to prevent blowout of the
electric arc. The test apparatus should be insulated from the
ground for the appropriate test voltage.
7.2 The test apparatus, electrodes, and calorimeter assem-
blies become hot during testing. Use protective gloves and
sleeves when handling these hot objects.
7.3 Use care if the specimen ignites or releases combustible
gases. An appropriate fire extinguisher should be readily
available. Ensure all materials are fully extinguished.
7.4 Immediately after each test, the electric supply shall be
shut off from the test apparatus and all other lab equipment
used to generate the arc. The apparatus and other lab equipment
shall be isolated and grounded. After data acquisition has been
completed, appropriate methods shall be used to ventilate the
test area before personnel entry. No one should enter the test
area prior to exhausting all smoke and fumes.
8. Sampling and Specimen Preparation
FIG. 7 Supply Bus and Arc Electrodes for Panels
8.1 Test Specimens for Two-Sensor Panel Test—The post-
laundered specimen size shall be at least 61.0 cm [26 in.] long
and at least 30.5 cm [12 in.] wide. Refer to Section 11, to
determine the number of samples required for the test.
6.8.1.1 Signal conditioning (if used) to minimize the noise 8.1.1 The length direction shall be cut in the warp or wale
spikes as a result of the arc shall be adjusted or selected, as not direction of the material.
to introduce a time shift in the response of the calorimeter
8.2 Laundering of Test Specimens and Weight Determina-
waveform.
tion:
6.8.2 The recording of temperature data from the monitor
8.2.1 Condition an adequate sampling and portion of fabric
and panel sensors shall start at least 0.1 s prior to arc initiation
to perform the fabric weight per Test Methods D3776/D3776M
to establish a reliable initial temperature of the sensors and
Option C for reporting as per Performance Specification F1506
shall continue at least 30 s after arc initiation.
fabric weight, actual.
6.8.3 The waveform recorders for current and voltage data
8.2.2 Launder the required amount of test material allowing
shall be acquired at a minimum rate of 2000 samples per
for fabric shrinkage in the laundering. Follow AATCC Labo-
second. The current and voltage acquisition system shall have
ratory Procedure 1-2021, Laboratory Procedure for Home
an accuracy of at least 3 %.
Laundering: Machine Wash Cycle 3 (Permanent Press), Wash
6.8.4 The start of acquisition for all the waveform recorders
Temperature IV (Hot: 49 °C ⁄120 °F), and Drying Procedure
for measuring the arc current, voltage, and calorimeter signals
Aiii (Tumble Dry, Permanent Press).
shall be synchronized.
8.2.2.1 The material shall be laundered three times and
6.9 Data Acquisition System Protection—Due to the nature dried once after the last wash according to the manufacturer’s
of this type of testing, the use of isolating devices on the care instructions, unless the material is labeled “do not laun-
calorimeter outputs to protect the acquisition system is recom- der.” If an alternate washing method is used, this shall be
mended. documented in the report.
F1959/F1959M − 24a
8.2.2.2 Specimens may be restored to a flat condition by 9.2 Calorimeter Verification by Spot Lamp—Calorimeters
pressing. shall be checked to verify proper operation. The verification
shall be done after assembly of the calorimeters into the
8.2.2.3 If an alternative laundry procedure is employed,
insulating material.
report the procedure used (see 13.1).
9.2.1 One acceptable verification method is to proceed as
8.2.3 For those materials that require cleaning other than
follows, that is, to expose each calorimeter to a fixed radiant
laundering, follow the manufacturer’s recommended practice
energy from a high intensity quartz spot lamp (typical 1000 W)
using three cleaning cycles followed by drying and note the
for 30 s as follows:
procedure used in the test reports (see 13.1.4).
9.2.1.1 The front surface of the spotlight is placed at the
8.3 Specimen Conditioning—Before arc testing, the speci-
same distance from each calorimeter. The spotlight beam
mens shall be conditioned at a temperature of 25 °C 6 8 °C
centered on and perpendicular to the calorimeter.
and at a relative humidity of 50 % 6 20 % for 1 h prior to
9.2.1.2 Care is taken to have the same initial temperature
testing. Test the finished product specimen within 20 min of
62 °C at each calorimeter and to avoid pre-heating of neigh-
removing it from these temperature and relative humidity
boring calorimeters while checking one calorimeter.
conditions.
9.2.1.3 The slope of the temperature rise signal and tem-
perature rise at 30 s for each calorimeter are measured and
8.4 Determination of the Arc Test Fabric Weight:
graphed.
8.4.1 Following laundering, drying, and conditioning (per
9.2.1.4 The slope and final temperature (at 30 s) for each
this standard), randomly select a minimum of 3 (three) test
sensor is compared.
panels and determine the fabric weight as follows:
9.2.1.5 Any calorimeter not fitting the temperature rise
8.4.2 Die-cut a circle of 3.8 cm [1.5 in.] to 7.6 cm [3.0 in.]
profile and having a final more than 4 °C variation from the
in diameter from the lower corner of at least three different test
average is suspect of faulty connection or assembly.
specimens, randomly selected to cover the length and width of
9.2.2 Other methods to adequately verify the operation of
the test sample.
each calorimeter against the average of a group of known good
8.4.3 Weigh all specimens in grams on a scale having an
sensors are acceptable.
accuracy of at least 0.001 g.
9.3 Calorimeter Verification by Arc Exposure—Prior to each
8.4.4 Calculate the arc test fabric weight of the test speci-
verification, position the electrodes of the test apparatus to
mens in grams per square meter as follows:
produce a 305 mm 6 5 mm gap. Position each two-sensor
Mass
panel and monitor the sensors so that the surface of each panel
Arc test fabric weight 5 (1)
Diameter is parallel and normal to the centerline of the electrodes
π ×
S D
2 according to 6.6 and Position 1 in Table 2.
9.3.1 Connect the fuse wire to the end of one electrode by
where:
making several wraps and twists and then to the end of the
Fabric weight = measured in g/m ,
other electrode by the same method. The fuse wire is pulled
Mass = weight of the fabric sample circle cutout, g,
tight and the excess trimmed. The electrical supply and test
Diameter = diameter of the die-cut circle, m, and
controller shall be adjusted to produce an arc current of 8 kA
π = 3.14159.
6 0.5 kA and arc duration of 167 ms 6 2 ms (that is, nominal
The fabric weight may also be expressed in ounces per
10 cycles) from 60 Hz supply or 170 ms 6 2 ms (that is,
square yard:
nominal 8.5 cycles) from 50 Hz supply.
9.3.2 The arc shall be initiated and the temperature versus
oz
Arc test fabric weight 5 weight g/m × 0.02949 (2)
S D ~ !
2 time response curve from each sensor shall be converted into
yd
8.4.5 Report the arc test fabric weight to at least the nearest
2 2
g/m (or nearest 0.1 oz ⁄yd if desired). TABLE 2 Precision of the Test Method
NOTE 1—s = repeatability standard deviation (pooled within-laboratory
8.5 Determine and report the actual fabric weight in accor-
r
standard deviation).
dance with Performance Specification F1506.
r = repeatability = 2.80 s .
r
8.6 Report the nominal fabric weight as provided by the
Sample A Sample B
Test Number ATPV ATPV
manufacturer and required in Performance Specification
2 2
cal/cm cal/cm
F1506.
1 5.1 7.3
2 5.1 6.4
3 5.3 7.4
9. Calibration and Standardization
4 5.6 6.9
5 5.3 7.0
9.1 Data Collection System—The measuring equipment
6 5.4 7.3
shall be calibrated by an accredited body with traceability to
national standards and SI units. Calibration checks of the Average 5.3 7.0
s 0.18 0.36
r
temperature measurement system shall be made at multiple
%CV 3.4 5.1
points and at levels to 500 °C. Due to the nature of the tests,
r 0.50 0.99
frequent calibration checks are recommended.
F1959/F1959M − 24a
an incident energy versus time response curve (see 12.2 and 10.1.1.1 Care shall be taken not to moisten the insulating
12.3) . The maximum of the incident energy response curve for board surrounding the calorimeter when cooling the copper
each sensor shall be determined and considered as the incident disc.
2 2
energy (total heat) in kJ/m [cal/cm ] measured by each sensor.
10.2 Panel and Monitor Sensor Assembly Care—The insu-
Because the arc does not follow a path that is equidistant from
lating materials shall be kept dry. For outdoor storage, the
each sensor, the resulting incident energy values vary between
two-sensor panels and monitoring sensors shall be covered
sensors.
during periods between tests to prevent water ingress and
9.3.3 The average of the incident energies of all the calori-
deterioration of the quality of the insulating material resulting
metric sensors located at the height of the middle of the arc
from exposure to the rain.
gap, that is, of all the six monitor sensors and all the sensors in
the center of each panel, which is part of the test apparatus
11. Procedure to Determine the Arc Rating
2 2 2
setting, shall be 315 kJ ⁄m 6 42 kJ ⁄m [7.5 cal ⁄cm 6
11.1 General Procedure:
1.0 cal ⁄cm ] when corrected for a distance of 305 mm.
11.1.1 Testing shall be carried out in an essentially still-air
9.3.4 The highest measured incident energy of any of the six
environment. If a forced ventilation system is used to ventilate
sensors located at the height of the middle of the arc gap shall
the area to carry away combustion products, smoke, and fumes,
not be more than 30 % greater than the average of the incident
this ventilation shall not be turned on until after the exposure,
energies of these sensors, and the lowest measured incident
and only after the data acquisition is completed.
energy of any of these sensors shall not be more than 30 %
lower than the average. 11.1.2 Initial Temperature—The temperature of the sensors
before each test shot shall be between 15 °C and 35 °C. The
9.3.5 The highest measured incident energy of any of the
sensors may be cooled or heated, for example, after exposure
three sensors located at the top of the arc gap shall not be more
with a jet of air or by contact with a cold or hot surface.
than 25 % greater than the average of the incident energies of
these sensors, and the lowest measured incident energy of any
11.1.3 Test parameters shall be 8 kA 6 0.5 kA arc current,
of these sensors shall not be more than 25 % lower than the 305 mm 6 5 mm electrode gap, stainless steel electrodes,
average.
panel and monitor sensor placement according to Table 2.
9.3.6 If the above incident energy distribution requirements
11.1.4 The monitor sensors shall be adjusted to position 1
are not fulfilled, inspect the test set-up and check the verifica-
for in
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