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: D229 − 19´1

Standard Test Methods for

Rigid Sheet and Plate Materials Used for Electrical
Insulation1
This standard is issued under the fixed designation D229; 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.

ε1 NOTE—The title of Table 1 was editorially corrected in August 2019.

This standard has been approved for use by agencies of the U.S. Department of Defense.

1. Scope* conversions to SI units that are provided for information only

1.1 These test methods cover procedures for testing rigid and are not considered standard.
electrical insulation normally manufactured in flat sheet or 1.6 This is a fire-test-response standard. See Sections 61
plate form. They are generally used as terminal boards, spacers, through 74, which are the procedures for assessing ignitability
voltage barriers, and circuit boards. and burning time under specific test conditions
1.2 Use Test Methods D619 (withdrawn) or Specification 1.7 This standard does not purport to address all of the
D710 for tests applying to vulcanized fibre. safety concerns, if any, associated with its use. It is the
1.3 Some of the test methods contained in this standard are responsibility of the user of this standard to establish appro-
similar to those contained in IEC 60893-2, which applies to priate safety, health, and environmental practices and deter-
rigid industrial laminated sheets based on thermosetting resins mine the applicability of regulatory limitations prior to use.
for electrical purposes. Specific precautionary statements are given in 31.1 and 1.8.
1.8 This standard measures and describes the response of
1.4 The test methods appear in the following sections: materials, products, or assemblies to heat and flame under
ASTM controlled conditions, but does not by itself incorporate all
Test
Test Sections Method
factors required for fire hazard or fire risk assessment of the
Acetone extractable matter 82 to 83 D494 materials, products, or assemblies under actual fire conditions.
Arc resistance 47 D495
Ash 56 to 60 ...
1.9 Fire testing is inherently hazardous. Adequate safe-
Bonding strength 49 to 54 ... guards for personnel and property shall be employed in
Flammability methods I and II 61 to 74 ... conducting these tests.
Coefficient of linear thermal expansion 76 D696
Compressive strength 25 D695 1.10 This international standard was developed in accor-
Conditioning 4 D6054 dance with internationally recognized principles on standard-
Dissipation factor 34 to 40 D669
Dielectric strength 28 to 33 D149 ization established in the Decision on Principles for the
Expansion (linear thermal) 75 D696 Development of International Standards, Guides and Recom-
Flexural properties 12 to 24 D790 mendations issued by the World Trade Organization Technical
Hardness (Rockwell) 55 D785
Insulation resistance and resistivity 41 to 46 D257 Barriers to Trade (TBT) Committee.
Permittivity 34 to 40 D150
Resistance to impact 26 D256 2. Referenced Documents
Tensile properties 7 to 11 D638
Thickness 5 to 6 D374 2.1 ASTM Standards:2
Tracking resistance 48 D2132
Warp or twist 76 to 81 ...
D149 Test Method for Dielectric Breakdown Voltage and
Water absorption 27 D570 Dielectric Strength of Solid Electrical Insulating Materials
1.5 The values stated in inch-pound units are to be regarded at Commercial Power Frequencies
as standard. The values given in parentheses are mathematical D150 Test Methods for AC Loss Characteristics and Permit-
tivity (Dielectric Constant) of Solid Electrical Insulation
1
These test methods are under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and are the direct responsibility of
2
Subcommittee D09.07 on Electrical Insulating Materials. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved March 1, 2019. Published March 2019. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1925. Last previous edition approved in 2013 as D229 – 13. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D0229-19E01. the ASTM website.

*A Summary of Changes section appears at the end of this standard

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 D229 − 19´1
D256 Test Methods for Determining the Izod Pendulum 2.2 IEC Standard:
Impact Resistance of Plastics IEC 60893–2 Specification for Rigid Industrial Laminated
D257 Test Methods for DC Resistance or Conductance of Sheets Based on Thermosetting Resins for Electrical
Insulating Materials Purpose, Methods of Tests4
D374 Test Methods for Thickness of Solid Electrical Insu- 2.3 International Organization for Standardization (ISO)
lation (Metric) D0374_D0374M Standard:
D494 Test Method for Acetone Extraction of Phenolic ISO 13943 Fire Safety: Vocabulary5
Molded or Laminated Products
D495 Test Method for High-Voltage, Low-Current, Dry Arc 3. Terminology
Resistance of Solid Electrical Insulation 3.1 Definitions—Rigid electrical insulating materials are
D570 Test Method for Water Absorption of Plastics defined in these test methods in accordance with Terminology
D617 Test Method for Punching Quality of Phenolic Lami- D883. The terminology applied to materials in these test
nated Sheets (Withdrawn 2003)3 methods shall be in accordance with the terms appearing in
D619 Test Methods for Vulcanized Fibre Used for Electrical Terminologies D883 and D1711. Use Terminology E176 and
Insulation ISO 13943 for definitions of terms used in this test method and
D638 Test Method for Tensile Properties of Plastics associated with fire issues. Where differences exist in
D669 Test Method for Dissipation Factor and Permittivity definitions, those contained in Terminology E176 shall be used.
Parallel with Laminations of Laminated Sheet and Plate
Materials (Withdrawn 2012)3 3.2 Definitions of Terms Specific to This Standard:
D695 Test Method for Compressive Properties of Rigid 3.2.1 In referring to the cutting, application, and loading of
Plastics the specimens, the following terms apply:
D696 Test Method for Coefficient of Linear Thermal Expan- 3.2.1.1 crosswise (CW), adj—in the direction of the sheet at
sion of Plastics Between −30°C and 30°C with a Vitreous 90° to the lengthwise direction.
Silica Dilatometer 3.2.1.1.1 Discussion—This is normally the weakest direc-
D710 Specification for Vulcanized Fibre Sheets, Rods, and tion in flexure. For some materials, including the raw materials
Tubes Used for Electrical Insulation used for manufacture of materials considered herein, this
D785 Test Method for Rockwell Hardness of Plastics and direction may be designated as the cross-machine direction or
Electrical Insulating Materials the weft direction.
D790 Test Methods for Flexural Properties of Unreinforced 3.2.1.2 edgewise loading, n—mechanical force applied in
and Reinforced Plastics and Electrical Insulating Materi- the plane of the original sheet or plate.
als 3.2.1.3 flatwise loading, n—mechanical force applied nor-
D792 Test Methods for Density and Specific Gravity (Rela- mal to the surfaces of the original sheet or plate.
tive Density) of Plastics by Displacement 3.2.1.4 lengthwise (LW), adj—in the direction of the sheet
D883 Terminology Relating to Plastics which is strongest in flexure.
D1674 Test Method for Testing Polymerizable Embedding 3.2.1.4.1 Discussion—For some materials, including the
Compounds Used for Electrical Insulation (Withdrawn raw materials used for the manufacture of materials considered
1990)3 herein, this direction may be designated as the machine
D1711 Terminology Relating to Electrical Insulation direction or the warp direction.
D1825 Practice for Etching and Cleaning Copper-Clad Elec- 3.2.2 In referring to bonding strength, the following term
trical Insulating Materials and Thermosetting Laminates applies:
for Electrical Testing (Withdrawn 2012)3 3.2.2.1 bonding strength, n—the force required to split a
D2132 Test Method for Dust-and-Fog Tracking and Erosion prescribed specimen under the test conditions specified herein.
Resistance of Electrical Insulating Materials 3.2.3 In reference to ignitability and burning time, the
D2303 Test Methods for Liquid-Contaminant, Inclined- following terms apply:
Plane Tracking and Erosion of Insulating Materials 3.2.3.1 ignition time, n—the elapsed time in seconds re-
D3487 Specification for Mineral Insulating Oil Used in quired to produce ignition under conditions of this test method.
Electrical Apparatus 3.2.3.2 burning time, n—the elapsed time that the specimen
D5032 Practice for Maintaining Constant Relative Humidity burns after removal of the ignition heat source under conditions
by Means of Aqueous Glycerin Solutions of this test method.
D6054 Practice for Conditioning Electrical Insulating Mate-
4. Conditioning
rials for Testing (Withdrawn 2012)3
E176 Terminology of Fire Standards 4.1 The properties of the materials described in these test
E197 Specification for Enclosures and Servicing Units for methods are affected by the temperature and moisture exposure
Tests Above and Below Room Temperature (Withdrawn
1981)3
4
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org.
5
Available from International Organization for Standardization, P.O. Box 56,
3
The last approved version of this historical standard is referenced on CH-1211, Geneva 20, Switzerland or from American National Standards Institute
www.astm.org. (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.

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 D229 − 19´1
of the materials to a greater or lesser extent, depending on the devices, indicate that the trade is able to measure sheets 1⁄32 and
particular material and the specific property. Control of tem- ⁄ in. (1 and 3 mm) in thickness to accuracy of 0.0015 in.
18

perature and humidity exposure is undertaken to: (1) obtain (0.0381 mm). (In the tests, σ, of 0.0005 in. (0.0127 mm) was
satisfactory test precision, or (2) study the behavior of the obtained.)
material as influenced by specific temperature and humidity 6.2 This test method has no bias because the value for
conditions. breaking strength is determined solely in terms of this test
4.2 Unless otherwise specified in these test methods or by a method itself.
specific ASTM material specification, or unless material be-
havior at a specific exposure is desired, condition test speci- TENSILE PROPERTIES
mens in accordance with Procedure A of Practice D6054 and 7. Test Specimens
test in the Standard Laboratory Atmosphere (23 6 1.1°C, 50 6
2 % relative humidity). 7.1 Machine the test specimens from sample material to
conform to the dimensions of sheet and plate materials in Fig.
THICKNESS 1.
5. Apparatus and Procedure 7.2 Prepare four LW and four CW specimens.
5.1 Measure thickness in accordance with Test Methods 8. Rate of Loading
D374. 8.1 The materials covered by these test methods generally
5.2 On test specimens, the use of a machinist’s micrometer exhibit high elastic modulus. Use any crosshead speed pro-
as specified in Method B is satisfactory for the determination of vided that the load and strain indicators are capable of accurate
thickness for all of the test methods that follow. Where it is measurement at the speed used, except use 0.05 in./min (1
convenient, use the deadweight dial micrometer, Method C. mm/min) in matters of dispute.
5.3 On large sheets, use Method B. Choose a micrometer 9. Procedure
with a yoke of sufficient size and rigidity to permit accurate
measurements in the center of the sheet. 9.1 Measure the tensile strength and elastic modulus in
accordance with Test Method D638 except as modified in the
6. Precision and Bias following paragraphs.
6.1 Results of comparative tests in several factories, mea- 9.2 Measure the width and thickness of the specimen to the
suring 36-in. (914-mm) square sheets by a variety of such nearest 0.001 in. (0.025 mm) at several points along the length

Nominal Thickness, T
Over 1⁄4 in. (6 mm) to 1⁄2 in. Over 1⁄2 in. (13 mm) to 1
14 ⁄ in. (6 mm) or Under Tolerance
Dimension (13 mm), incl in. (25 mm), inclA
Type I Type IIB Type I Type IIB Type I
mm in. mm in. mm in. mm in. mm in. mm in.
C—Width over-all 19.05 0.750 19.05 0.750 28.57 1.125 28.57 1.125 38.10 1.500 ±0.40 + 0.016
−0.00 −0.000
W—Width of flat section 12.70 0.500 6.35 0.250 19.05 0.750 9.52 0.375 25.40 1.000 + 0.12 + 0.005
F—Length of flat section 57.1 2.25 57.1 2.250 57.1 2.25 57.1 2.25 57.1 2.25 ±0.40 ±0.016
G—Gauge lengthC 50.8 2.00 50.8 2.00 50.8 2.00 50.8 2.00 50.8 2.00 ±0.40 ±0.016
D—Distance between grips 114 41⁄2 133 51⁄4 114 41⁄ 2 133 51⁄4 133 51 ⁄ 4 ±3 ± 1⁄8
L—Length over-all 216 81⁄2 238 93⁄8 248 93⁄ 4 257 101⁄8 305 12 min min
Rad.—Radius of fillet 76 3 76 3 76 3 76 3 76 3 min min
A
For sheets of a nominal thickness over 1 in. (25.4 mm) machine the specimens to 1 in. (25.4 mm) ± 0.010 in. (0.25 mm) in thickness. For thickness between 1 in. (25.4
mm) and 2 in. (51 mm), machine approximately equal amounts from each surface. For thicker sheets, machine both surfaces and note the location of the specimen with
reference to the original thickness.
B
Use the type II specimen for material from which the Type I specimen does not give satisfactory failures in the gauge length, such as for resin-impregnated compressed
laminated wood.
C
Test marks only.

FIG. 1 Tension Test Specimen for Sheet and Plate Insulating Materials

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 D229 − 19´1
of the flat section, which is indicated as Dimension F in Fig. 1. 13. Rate of Loading
Record the minimum values of cross-sectional area so deter- 13.1 The materials covered by these test methods generally
mined. rupture during flexural testing at small deflections. Therefore,
9.3 Place the specimen in the grips of the testing machine, Procedure A (strain rate of 0.01/min) is specified whenever it is
taking care to align the long axis of the specimen and the grips desired to obtain the modulus of elasticity. Use any crosshead
with an imaginary line joining the points of attachment of the speed that produces failure in no less than 1 min when flexural
grips to the machine. Allow 0.25 in. (6.3 mm) between the ends strength only is desired, provided that the load indicator is
of the gripping surfaces and the shoulders of the fillet of the flat capable of accurately indicating the load at the speed used, and
test specimen; thus, it is important that the ends of the gripping except that in all matters of dispute, a crosshead speed that
surfaces be the indicated distance apart, as shown in Fig. 1, at produces the strain rate specified in Procedure A shall be
the start of the test. Tighten the grips evenly and firmly to the considered to be the referee speed.
degree necessary to prevent slippage of the specimen during
the test, but not to the point where the specimen would be 14. Procedure
crushed. 14.1 Measure the flexural strength and modulus of elasticity
in accordance with Procedure A of Test Methods D790, except
9.4 Tensile Strength—Set the rate of loading. Load the
that where modulus of elasticity is desired use a load-deflection
specimen at the indicated rate until the specimen ruptures.
recorder with appropriate deflection transmitter.
Record the maximum load (usually the load at rupture).
9.5 Elastic Modulus—When elastic modulus is desired, use 15. Report
a load-extension recorder with appropriate extension transmit- 15.1 Report the following information:
ter and proceed as in 9.3. Attach the extension transmitter, and 15.1.1 Complete identification of the material tested,
proceed as in 9.4. 15.1.2 Conditioning if other than specified,
15.1.3 Speed of testing if other than Procedure A speed,
10. Report 15.1.4 Calculated flexural strength, average, maximum, and
10.1 Report the following information: minimum in lb/in.2 (MPa), for LW and CW specimens,
10.1.1 Complete identification of the material tested, respectively,
15.1.5 Calculated tangent modulus of elasticity when
10.1.2 Type of test specimen (I or II),
applicable, average, maximum, and minimum, for LW and CW
10.1.3 Conditioning if other than specified,
specimens, respectively, and
10.1.4 Speed of testing, 15.1.6 Any other flexural property calculated from the
10.1.5 Calculated tensile strength, average, maximum, and measurements obtained.
minimum in lb/in.2 (MPa), for LW and CW specimens,
respectively, 16. Precision and Bias
10.1.6 Calculated elastic modulus when applicable, 16.1 This test method has been in use for many years, but no
average, maximum, and minimum in lb/in.2 (MPa), for LW and statement for precision has been made and no activity is
CW specimens, respectively, and planned to develop such a statement.
10.1.7 Any other tensile property calculated from the mea-
16.2 This test method has no bias because the value for
surements obtained.
breaking strength is determined solely in terms of this test
method itself. See Test Methods D790 for a discussion of
11. Precision and Bias
precision and bias for testing of flexural properties of plastics.
11.1 This test method has been in use for many years, but no
statement for precision has been made and no activity is FLEXURAL PROPERTIES AT ELEVATED
planned to develop such a statement. TEMPERATURE
11.2 This test method has no bias because the value for 17. Scope
breaking strength is determined solely in terms of this test 17.1 This test method covers the determination of flexural
method itself. See Test Method D638 for a discussion of properties at elevated temperature, and as a function of time of
precision and bias for tensile testing of plastics. exposure to elevated temperature.
FLEXURAL PROPERTIES 17.2 This international standard was developed in accor-
dance with internationally recognized principles on standard-
12. Test Specimens ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
12.1 Test four LW and four CW specimens machined from mendations issued by the World Trade Organization Technical
sample material in accordance with Test Methods D790. Barriers to Trade (TBT) Committee.
12.2 Do not use conventional flexure tests in a flatwise
direction for materials thinner than 1/32 in. (1 mm). Do not use 18. Significance and Use
conventional flexure tests in an edgewise direction for materi- 18.1 This test method provides useful engineering informa-
als thinner than ¼ in. (6 mm). tion for evaluating the mechanical behavior of rigid electrical

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 D229 − 19´1
insulation at elevated temperature. When the proper exposure 21. Conditioning
and test temperatures are chosen, depending on the material 21.1 No special conditioning is required for specimens that
and end-use operating temperature, use the test method as one are to be tested after more than 1-h exposure at elevated
means of indicating relative thermal degradation of rigid temperature.
insulating materials.
22. Procedure
19. Apparatus
22.1 Adjust the rate of loading in accordance with Section
19.1 Testing Machine—A universal testing machine and 13 and test the specimen in accordance with Section 14.
accessory equipment in accordance with Test Methods D790.
Apparatus that is exposed to elevated temperature during the 22.2 Age in the flexural test enclosure the specimens that
test shall be adjusted to function normally at the elevated are to be tested 1 h or less after exposure to elevated
temperature and, where necessary, accuracy shall be verified by temperature.
calibration at the test temperature. 22.3 Exposures at elevated temperature for 15 min or less
shall not include the time (previously determined from the
19.2 Test Enclosure—A test enclosure conforming to the
specimen with the thermocouple) that is required for the
Type I, Grade B, temperature requirements of Specification
specimen to reach the specified temperature. Rather, begin
E197. The test enclosure shall be permitted to rest on the
exposures for intervals of 15 min or less when the specimen
testing machine table, in which case the top shall have a hole reaches the specified temperature and end when the specified
of sufficient size so that adequate clearance is provided for the exposure period has expired.
loading nose, or the test enclosure shall be permitted to rest on
a dolly and contain a cradle which is supported by the loading 22.4 Age in the heat-aging oven the specimens that are
members of the machine. exposed to elevated temperature for more than 1 h. Do not
allow the specimens to cool when removed from the heat-aging
19.3 Heat Aging Oven—A heat aging oven for conditioning oven, but rather transfer them in the mobile-transfer oven or
specimens at the test temperature for periods of more than 1 h. wrap them in previously heated thick pad of heat resistant
The oven shall conform to the requirements for Type I, Grade material. Place them in the flexural test chamber which has
A, units of Specification E197, except with respect to the time been previously heated to the specified temperature.
constant.
22.5 Consider the flexural test enclosure and accessory
19.4 Specimen Transfer Device—A means of transferring equipment inside at equilibrium when a dummy specimen
the test specimens from the heat-aging oven to the test fitted with an internal thermocouple, and placed on the
enclosure when testing specimens exposed to elevated tem- supports, has reached the specified temperature, as determined
perature for periods of more than 1 h. Transfer the specimens by the thermocouple measurement. Place test specimens in the
without cooling either in a small mobile transfer oven or flexural test enclosure only after equilibrium has been estab-
wrapped in previously heated thick pad of heat resistant lished.
material.
23. Report
19.5 Thermocouple—Thermocouple made with No. 30 or
28 B & S gauge thermocouple calibration wires to determine 23.1 Report all applicable information plus the following:
the temperature of the specimen. Any suitable indicating or 23.1.1 Temperature at which the specimens were exposed
recording device shall be used that provides an overall (junc- and tested,
tion and instrument) accuracy of 62°C. 23.1.2 Time of exposure, and
23.1.3 Where sufficient measurements are made, a plot of
20. Test Specimen flexural strength as ordinate and time at elevated temperature
20.1 Test the specimen flatwise and lengthwise and machine as abscissa, for each temperature chosen.
from sample material in accordance with Section 12.
24. Precision and Bias
20.2 Where it is desired to evaluate relative thermal
24.1 This test method has been in use for many years, but no
degradation, specimens shall be 1⁄8 in. (3 mm) in nominal
statement for precision has been made and no activity is
thickness.
planned to develop such a statement.
20.3 Fit at least one specimen of each thickness for each
24.2 A statement of bias is not available because of the lack
sample material with a hole drilled into an edge that rests of a standard reference material for this property.
outside the support to a depth of at least 1⁄2 in. (13 mm). Insert
the thermocouple junction in this hole and cement. Use this COMPRESSIVE STRENGTH
specimen to determine the temperature of the specimen on the
support and the time required to reach the specified tempera- 25. Procedure
ture for specimens that are tested after 15-min exposure or less.
25.1 Determine the compressive strength in accordance
20.4 Test five specimens at each temperature. with Test Method D695, except test four specimens.

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 D229 − 19´1
RESISTANCE TO IMPACT length by the thickness of the material. Minimum thickness of
the material shall be 1⁄8 in. (3 mm). Using a twist drill with a
26. Procedure point angle of 60 to 90°, drill a hole in the approximate center
26.1 Determine the resistance to impact in accordance with of the 1-in. (25-mm) length in a direction parallel with the flat
Test Methods D256, using Method A or C, whichever is sides, to a depth of 7⁄16 in. (11 mm), leaving a thickness of
1⁄16 in. (1.6 mm) to be tested. Insert a snug-fitting metal pin
applicable, except test four specimens conditioned in accor-
dance with 4.2 of these test methods. electrode, with the end ground to conform with the shape of the
drill used in the hole. Place the specimen on a flat metal plate
WATER ABSORPTION that is at least 11⁄2 in. (38 mm) in diameter. This plate serves as
the lower electrode. Thus, in effect, the material is tested
27. Procedure parallel with the flat sides in a point-plane dielectric gap. The
27.1 Determine the water absorption in accordance with diameter of the hole shall be as shown in the following table:
Test Method D570, except test all sample material for water- Nominal Hole Diameter for Pin
soluble matter unless it has been previously demonstrated by Nominal Thickness of Sheets Electrode
test that there is negligible water-soluble matter in the sample. 1⁄8 to 1⁄4 in. (3 to 6 mm) ⁄ in. (1.6 mm)
1 16
Test four specimens. >1⁄4 in. (6 mm) ⁄ in. (3 mm)
18

DIELECTRIC STRENGTH 29.3 Parallel Test, Tapered-Pin Method:

29.3.1 Significance—Sheet and plate insulation, particularly
28. Surrounding Medium laminated sheets, are frequently used in service in a manner
28.1 Except as noted below, perform tests in a surrounding such that the full thickness of the insulation is exposed to a
medium of transformer oil meeting all of the requirements for voltage stress parallel to the flat sides between pin-type inserts.
Type I mineral oil of Specification D3487. Test at room This method (employing tapered-pin electrodes) is
temperature, unless otherwise specified. recommended, rather than the method in 29.2, when it is
desired to simulate the service condition described and when
NOTE 1—A liquid medium is specified to obtain breakdown of a the need for obtaining quantitative dielectric breakdown data is
reasonable size test specimen rather than flashover in the medium. Testing secondary to acceptance and quality control needs.
in a liquid medium limits the likelihood of flashover but will not always
prevent it, especially with the tapered-pin method. 29.3.2 Nature of Test—The tapered-pin electrodes extend
Transverse tests performed in an air medium will generally result in beyond the test specimen on both flat sides. Therefore, it is
lower breakdown values than transverse tests performed in the liquid possible that oil-medium flashover or oil-specimen interface
medium. This is particularly true when porous materials are tested. It is failure will obscure specimen volume dielectric breakdown.
possible that tests performed in the liquid medium on specimens that have
This method is suited, consequently, for use primarily as a
been thermally aged will produce misleading conclusions when change in
dielectric strength is utilized as a criterion of thermal degradation. proof-type test, that is, to determine only that a material will
Transverse tests in air for porous materials and thermally aged materials withstand without failure a specified minimum electric stress
are encouraged. It is possible to utilize various schemes for potting or applied in a prescribed manner under specified conditions. In
gasketing the electrodes to prevent flashover. Apparatus is being evaluated some limited cases, however, (for example, specimens condi-
for use in a standard method for transverse tests in air. See the
Surrounding Medium section of Test Method D149.
tioned in water) it is possible to employ the tapered-pin method
to obtain quantitative specimen dielectric breakdown data.
28.2 In the special case of material tests on parallel-tapered- When numerous tests are made, it is potentially difficult to
pin configuration where breakdown voltages exceed 50 kV maintain the oil-medium in such a condition as to obviate
give special attention to the cleanliness, dryness, and tempera- flashover (with specimen in place between pins spaced 1 in.
ture of the surrounding medium. The substitution of dibutyl (25 mm) apart) at voltage magnitude above 50 kV. The
phthalate for transformer oil has been found to be satisfactory. practical limit, therefore, when using an oil-medium is 50 kV.
28.3 During a parallel-tapered-pin test, the breakdown of This limit can be increased to 80 kV by the use of dibutyl
the oil above the specified value for the material is not always phthalate.
a proof that actual specimen breakdown occurred, since the 29.3.3 Test Specimens and Electrodes— The test specimen
specimen surface structure and its permittivity will influence shall be 2 by 3 in. (50 by 75 mm) by the thickness of the sheet.
the breakdown voltage of a given oil between the tapered pins The electrodes shall be USA Standard tapered pins (such as
with specimen in place. Morse, Brown & Sharpe, or Pratt & Whitney) having a taper of
1⁄4 in. ⁄ft (20 mm/m). For specimen thicknesses up to and
29. Electrodes and Test Specimens including 1⁄2 in. (13 mm), use No. 3 USA Standard tapered
29.1 Transverse Test—Use 2-in. (51-mm) diameter elec- pins6 3 in. (76 mm) long and having a diameter of 7⁄32 in.
trodes (Type 1 of Test Method D149) for voltage stress applied (5.6 mm) at the large end. For specimen thicknesses over 1⁄2 in.
perpendicular to the flat side of the specimen. The test (13 mm) up to and including 2 in. (51 mm), use No. 4 USA
specimen shall be of such size that flashover in the oil medium Standard Pins6 4 in. (102 mm) long having a diameter at the
does not occur before specimen breakdown. In general, a 4-in. large end of 1⁄4 in. (6 mm). Drill two 3⁄16-in. (5-mm) diameter
(102-mm) square will be satisfactory.
29.2 Parallel Test, Point-Plane Method— The test speci- 6
For information on tapered pins, see Kent’s Mechanical Engineers’ Handbook,
mens shall be 1⁄2 in. (13 mm) in width by 1 in. (25 mm) in 12th edition, Design and Production Volume, Section 15, p. 14.

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 D229 − 19´1
holes, centrally located, 1 in. (25 mm) apart, center to center, Breakdown Voltage by Rate of Test Voltage Rise, V/s
and perpendicular to the faces of the specimen. Ream the holes Short-Time Method, kV

to a sufficient depth to allow the pins to extend approximately 25 or less 17

1 in. (25 mm) from the small ends of the holes. Insert the Over 25 to 50, incl 33
Over 50 to 100, incl 83
electrodes from opposite sides of the specimen, after the Over 100 167
conditioning period. Metal spheres of 1⁄2 in. (13-mm) diameter
31.4 Proof-Type Test—Make the tests by either the step-by-
placed on the extremities of the tapered pins have the potential,
step or the slow-rate-of-rise method as follows:
in some cases, to decrease the tendency to flashover in the oil.
31.4.1 Step-by-Step Method—Starting at the prescribed per-
centage of the minimum failure voltage as specified in the
30. Conditioning appropriate material specification, increase the test voltage in
30.1 Condition five specimens in accordance with Section 1-min steps. Use test voltage increments of 1.0 kV for starting
4. In the case of the Parallel Test, Tapered Pin Method, tests are voltages of 12.5 kV or less, 2.0 kV for starting voltages over
usually performed on unconditioned specimens. However, in 12.5 to 25 kV, inclusive, and 5.0 kV for starting voltages over
determining the effects of exposure to moisture or water using 25 kV. Hold the test voltage for 1 min at the specified minimum
this test, Procedure E of Practice D6054 is recommended. failure voltage.
31.4.2 Slow-Rate-of-Rise Method—Starting at the pre-
31. Procedure scribed percentage of the minimum failure voltages specified in
the appropriate material specification, increase the test voltage
31.1 Warning: Lethal voltages are potentially present dur- at a uniform rate as indicated until the specified minimum
ing this test. It is essential that the test apparatus, and all failure voltage is reached. Calculate the slow rate-of-rise, in
associated equipment electrically connected to it, be properly volts per second, as follows:
designed and installed for safe operation. Solidly ground all Slow rate 2 of 2 rise, V/s 5 ~ V f 2 V s ! / ~ n 3 60! (1)
electrically conductive parts that any person might come into
contact with during the test. Provide means for use at the where:
completion of any test to ground any parts which: were at high V f = specified minimum failure voltage,
voltage during the test; have potentially acquired an induced Vs = starting voltage, and
charge during the test; potentially retain a charge even after n = total number of 1-min steps that would be obtained
disconnection of the voltage source. Thoroughly instruct all using the step-by-step method of 31.4.1.
operators in the proper way to conduct tests safely. When 32. Report
making high voltage tests, particularly in compressed gas or in
oil, the energy released at breakdown has the potential to be 32.1 Report the following information:
sufficient to result in fire, explosion, or rupture of the test 32.1.1 Material identification,
chamber. Design test equipment, test chambers, and test 32.1.2 Method used (from Section 29),
specimens so as to minimize the possibility of such occur- 32.1.3 Nature of surrounding medium,
rences and to eliminate the possibility of personal injury. 32.1.4 Temperature of the solid specimen before applying
voltage,
31.2 Determine the dielectric strength, dielectric breakdown 32.1.5 Method of voltage application (from Section 31),
voltage, and dielectric proof-type test in accordance with Test 32.1.6 Thickness of the test specimen,
Method D149, except as follows: Make the tests perpendicular 32.1.7 Individual and average dielectric strength values in
to or parallel with the flat sides, or both, depending upon volts per mil (kilovolts per millimetre) for the Transverse Test
whether the stress on the material when in use is to be and the Parallel Test, Point Plane Method, and
perpendicular to or parallel with the flat sides, or both. 32.1.8 Individual and average dielectric breakdown volt-
ages in kilovolts for the Parallel Test, Tapered Pin Method.
31.3 Make the tests by either the short-time method, the
step-by-step method, or the slow-rate-of-rise method as fol- 33. Precision and Bias
lows: 33.1 This test method has been in use for many years, but no
31.3.1 Short-Time Method—Increase the voltage at the rate statement for precision has been made and no activity is
of 0.5 kV/s. planned to develop such a statement.
31.3.2 Step-by-Step Method—Apply the voltage at each step 33.2 A statement of bias is not available because of the lack
for 1 min and increase it in the following increments: of a standard reference material for this property.
Breakdown Voltage by Increment of Increase of Test
Short-Time Method, kV Voltage, kV PERMITTIVITY AND DISSIPATION FACTOR
25 or less 1.0
34. Apparatus
Over 25 to 50, incl 2.0
Over 50 to 100, incl 5.0 34.1 Specimen Holder—A well-designed specimen holder
Over 100 10.0
to support and shield the specimen and provide for connection
31.3.3 Slow-Rate-of-Rise Method—Increase the voltage as of the electrodes to the terminals of the measuring apparatus is
follows: recommended. Two-terminal and three-terminal holders are

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 D229 − 19´1
described in Test Methods D150. A specimen holder for use at 36.3.1 For laminated thermosetting materials, except as
elevated temperatures is described in Methods D1674. specified in 36.3.2, saw standard rectangular specimens from
34.2 Measuring Apparatus—Use a suitable bridge or sheets to the following dimensions for measurements at 1
resonant-circuit apparatus conforming to the requirements of MHz:
Test Methods D150. The choice of equipment will depend Thickness of Sheet Size of Specimen
upon the frequency at which measurements are to be made, and Up to ⁄ in. (1.2 mm), incl
3 64 2 by 2 in. (50 by 50 mm)
in certain cases upon the applied voltage gradients when such Over 3⁄64 in. (1.2 mm) to 3⁄32 in. (2.4 mm) 3 by 3 in. (75 by 75 mm)
are specified. Over 3⁄32 in. (2.4 mm) to 1⁄4 in. (6.4 mm) 4 by 4 in. (100 by 100 mm)
Over 1⁄4 in. (6.4 mm) to 2 in. (50 mm) 4 by 8 in. (100 by 200 mm)
35. Electrodes (see Note 2) 36.3.2 For ultra-thin thermosetting laminates, particularly
35.1 Apply electrodes to the specimens. Most of the elec- of the glass-base type, the specimens for measurements at 1
trode materials described in Test Methods D150 are suitable MHz shall be small disks accurately die-cut from larger 2-in.
except fired-on silver. Metal foil and conducting silver paint (50-mm) disks that have been coated previously on both sides
are generally recommended, but use the latter only for mea- with conducting silver paint first air-dried at room temperature,
surements at elevated temperatures. For laminated thermoset- then heated in a circulating-air oven at 50°C for about 30 min,
ting materials to be tested at 1 MHz, use either metal foil and finally cooled in a desiccator. The recommended specimen
attached by a thin film of petrolatum or conducting silver paint, diameters are as follows:
and the electrodes shall completely cover both sides of the Thickness of Sheet Diameter of Specimen
specimen. For testing ultra-thin, that is, up to a thickness of Up to 0.003 in. (0.07 mm), approximately 0.50 in. (12.5 mm)
about 0.03 in. (0.75 mm), glass-base laminated thermosetting Over 0.003 in. (0.07 mm) to 0.010 in. (0.25 mm) 0.75 in. (19.0 mm)
materials, use only conducting silver paint electrodes. When Over 0.010 in. (0.25 mm) to 0.030 in. (0.75 mm) 1.00 in. (25.4 mm)
the same specimen is used for Condition A and for tests after 36.4 Unless otherwise specified, clean specimens in accor-
immersion in water, always remove metal foil electrodes and dance with the manufacturer’s recommendation prior to appli-
clean off the petrolatum with a suitable solvent before immer- cation of electrodes and conditioning.
sion. Silver paint electrodes, on the other hand, are not
removed prior to immersion of specimens in water. 37. Conditioning
NOTE 2—It has been found that satisfactory permittivity and dissipation 37.1 The permittivity and loss characteristics, especially at
factor measurements can be made on many sheet materials, particularly at the lower frequencies, of the materials covered by these test
radio frequencies, by the non-contacting electrode techniques (air-gap, methods are significantly affected by conditioning.
liquid displacement, and two-fluid displacement) described in Test Meth-
ods D150 when appropriate test cells and liquids are available. Such 37.2 Unless otherwise specified, condition specimens for at
methods are permissible when agreed upon by the parties concerned. No least 40 h at 50 % relative humidity, 23°C, immediately prior to
electrodes of any kind are then applied directly to the test specimens. performance of the electrical tests.
36. Test Conditions 37.3 When water immersion conditions are specified, at the
end of the conditioning period remove each specimen
36.1 Unless otherwise specified, test two specimens of each
separately, wipe or blot with lint-free absorbent paper towels,
material.
and test within approximately 2 or 3 min after removal from
36.2 The thickness of the specimens is usually the manu- the water.
factured thickness of the sheet, but it is potentially necessary
and is permissible to machine very thick specimens down to a 38. Procedure
usable thickness. Determine the thickness in accordance with 38.1 Measure the permittivity and dissipation factor in
Section 5, except in the cases of ultra-thin thermosetting accordance with Test Methods D150, in the Standard Labora-
glass-base laminates, calculate the mean effective thicknesses tory Atmosphere of 50 6 2 % relative humidity, 23 6 1°C. Use
from the mass in grams and density in grams per cubic other temperatures and humidities to meet special require-
centimetre of accurately die-cut disks 2.00 in. (50.8 mm) in ments. Follow instructions given in manuals provided by
diameter, as follows: manufacturers of testing apparatus employed.
thickness 5 ~ 0.01942 3 mass/density! in. (2) 38.2 In the case of the small disk specimens of ultra-thin
laminates at 1 MHz, support the specimen directly on the
5 ~ 0.04933 3 mass/density! mm
high-voltage terminal of the apparatus and connect the speci-
Determine the densities of the 2.00-in. disks in accordance men to the low-voltage or ground terminal by means of a small
with Test Methods D792. spring bronze clip attached to a banana plug. Place a coin or
36.3 Generally, specimens shall be of such size as is similar metal disk, smaller than the specimen, between the free
practicable with the apparatus used. For measurements at end of the clip and the low voltage or ground electrode to
frequencies up to about 1 MHz, it is recommended that the improve contact and avoid damage to the specimen. In calcu-
specimens be of such size that the measured capacitances will lations of the permittivities of these small disk specimens,
be in the approximate range from 50 to 150 picofarads (pF). At neglect the correction for edge capacitance.
higher frequencies, smaller specimens giving capacitances of 38.3 When measurements are made at commercial power
10 to 30 pF, approximately, will be required. frequencies, it is possible that relatively high voltages will have

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 D229 − 19´1
to be used to obtain adequate sensitivity or to meet a require- 40. Precision and Bias
ment that tests be made at a specified voltage gradient on the
40.1 This test method has been in use for many years, but no
specimen. The applied voltage shall not exceed the limitations
of the instrument used, and must be below the corona starting statement for precision has been made and no activity is
voltage of the specimen-electrode system. planned to develop such a statement.
40.2 A statement of bias is not available because of the lack
39. Report of a standard reference material for this property.
39.1 Report the following information:
INSULATION RESISTANCE AND RESISTIVITY
39.1.1 Description of the material tested, including the
thickness,
41. Electrodes
39.1.2 Specimen size and type of electrodes employed,
39.1.3 Temperature and relative humidity during test, 41.1 Electrodes for Volume and Surface Resistance —Apply
39.1.4 Permittivity and dissipation factor of each specimen, air drying or baking conductive silver paint to the test
and the averages, for each test frequency and testing condition, specimen, approximately centered, in accordance with Fig. 2 of
and Test Methods D257, with the following dimensions:
39.1.5 Voltage applied to specimen during test. D1 = 2 in. (51 mm)

FIG. 2 Insulation Resistance and Resistivity Specimen Holder Brought Through Split-Type Removable Oven Door

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 D229 − 19´1
D2 = 21⁄2 in. (63.5 mm) accordance with Practice D5032. Fit the chamber containing
D3 = 3 in. (76 mm) the solution with holders to support the specimen and make
NOTE 3—Some materials are metal clad. It is potentially desirable to
electrical connection for the resistance measurement. Ther-
utilize the metal foil clad to the insulating material for electrodes. In this mally insulate the chamber to prevent sudden temperature
event, follow specifications applicable to the specific material for etching changes that can cause precipitation inside the chamber. Fit the
the clad foil into a suitable electrode pattern. chamber with a small blower or propeller to circulate the air
41.2 Electrodes for Insulation Resistance—Metal electrodes inside. Place the thermally insulated chamber inside an oven
in accordance with Fig. 3 of Test Methods D257 for materials maintained at the specified temperature. Fig. 4 illustrates a
1⁄32 in. (1 mm) or more in thickness, and in accordance with suitable humidity test enclosure.
Fig. 1 of Test Methods D257 for thinner materials, shall be 43.3 Constant-Temperature Oven—The oven used for el-
used. evated temperature resistance measurements shall conform to
the Grade B requirements of Specification E197, except for the
42. Test Specimen time constant. Fit the oven with holders to support the
42.1 The surface resistance, and therefore also insulation specimen and make electrical connection for the resistance
resistance, have the potential to be affected by the manner in measurements without introducing shunting resistances that
which the specimen is prepared, cleaned, and handled. Before interfere with the measurements. Fig. 2 and Fig. 3 illustrate a
insertion or application of the electrode, clean each specimen suitable arrangement.
to remove release agents or other surface contaminants that can
44. Conditioning
influence the measurement of resistance. Take care that the
cleaning procedure does not have a solvent or swelling action 44.1 Resistance properties of materials covered by these test
on the material itself. Handle specimens by touching the edges methods are very sensitive to moisture and temperature con-
only. Nylon, rayon, or surgical rubber gloves are recommended ditions. Controlled conditioning is required.
as a precaution against possible contamination of the speci- 44.2 Use any controlled condition to obtain the resistance
mens. information required. The resistance properties of the materials
42.2 Specimen for Volume and Surface Resistance Test— covered by these test methods are generally so high at fairly
The specimen shall be a 31⁄2-in. (89-mm) square or disk. dry and room temperature conditions that the resistance values
have little, if any, practical engineering significance other than
42.3 Specimen for Insulation Resistance Test—The speci-
to establish quickly that they are high. The standard conditions
men shall be a 3 by 2-in. (76 by 51-mm) rectangle for material
1⁄32 in. (1 mm) or more in thickness. For thinner materials, a
recommended for obtaining useful engineering information are
as follows:
21⁄2-in. (63.5-mm) wide strip, rectangular in shape, shall be
44.2.1 Procedure C of Practice D6054, resistance to be
used.
measured while the specimen is in the conditioning
42.4 Test four specimens. atmosphere, and the conditioning to be accomplished in a
forced-air circulated medium.
43. Conditioning Enclosure 44.2.2 Measure the volume resistance of the specimen at the
43.1 Use a conditioning enclosure to provide the specified hottest-spot temperature at which the specimen is expected to
conditions, to support the specimens, and facilitate electrical be used, and 15 min after the specimen has reached and been
connections for resistance measurements without introducing maintained at this temperature, as determined by means of a
shunting resistances that interfere with the measurements. thermocouple in the specimen so placed as to measure the
43.2 Humidity Test Enclosure—Obtain the specified relative temperature of the specimen without interfering with the
humidity at the specified temperature by the use of solutions in resistance measurement.
45. Procedure
45.1 Determine the insulation resistance, volume resistance
and resistivity, and surface resistance and resistivity in accor-
dance with Test Methods D257 and as further provided in the
following paragraphs.
45.2 At the end of the conditioning period, determine the
presence of shunting resistances. If these cannot be effectively
eliminated by guarding with the instrumentation used, make
proper correction by calculation.
45.3 Measure the resistance of the specimen after applying
500 V of d-c potential difference for 1 min.
46. Precision and Bias
46.1 This test method has been in use for many years, but no
FIG. 3 Test Specimen for Insulation Resistance and Resistivity statement for precision has been made and no activity is
Tests Mounted in Specimen Holder planned to develop such a statement.

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FIG. 4 Humidity Test Enclosure for Insulation Resistance and Resistivity Tests

46.2 A statement of bias is not available because of the lack 51. Test Specimen
of a standard reference material for this property.
51.1 Any specimen 3⁄16 in. (5 mm) or thicker is permitted to
ARC RESISTANCE be tested. The bonding strength is dependent on specimen
thickness, however, and therefore compare only specimens of
47. Procedure the same thickness.
47.1 Determine the arc resistance in accordance with Test
51.2 The standard specimen shall be 0.500 6 0.005 in. (12.7
Method D495.
6 0.127 mm) thick and 1 in. (25.4 mm) square. Two parallel
TRACKING RESISTANCE edges shall be smooth within 60.001 in. (60.025 mm).

48. Procedure 51.3 Test four specimens.

48.1 Determine the dust-and-fog tracking resistance in ac- 52. Procedure
cordance with Test Method D2132.
48.2 Determine inclined-plane tracking resistance in accor- 52.1 Place the specimen with smooth edge on the testing
dance with Test Method D2303 using the variable voltage machine table or a flat steel plate that rests on the testing
method. machine table. Accurately center the steel ball between the
edges and ends of the specimen.
BONDING STRENGTH
52.2 Load the specimen through the steel ball, using a
49. Significance and Use crosshead speed not exceeding 0.050 in./min (1.3 mm/min)
until the specimen splits. Record the maximum load sustained
49.1 The bonding strength is a measure of the adhesive
before or prior to failure.
strength of a heterogeneous material of the type covered by
these test methods. It is useful as a manufacturing control or 52.3 Record as the bonding strength the maximum force
acceptance test. It is useful to indicate whether or not a obtained.
thermosetting laminated plastic is properly cured.
53. Report
50. Apparatus
50.1 Use any universal testing machine, provided it is 53.1 Report the following information:
accurate to 1 % of the lowest load to be applied. The machine 53.1.1 The thickness of the material, and
shall be fitted with a head containing a 10-mm diameter steel 53.1.2 The load, expressed in pounds or kilograms, required
ball. to split the specimen.

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54. Precision and Bias to provide test methods that allow the relative comparison of
54.1 This test method has been in use for many years, but no the ignitability of materials and the extent of burning if ignition
statement for precision has been made and no activity is does occur.
planned to develop such a statement. 61.2 Two methods are provided: Method I, is a relatively
54.2 A statement of bias is not available because of the lack simple test that requires inexpensive apparatus. It is intended
of a standard reference material for this property. primarily as a control test and for screening quickly materials
that exhibit improved fire performance from a population of
ROCKWELL HARDNESS various types. Use this method to establish relative burning
characteristics of tested plastic materials on a comparative
55. Procedure basis. The equipment specified in Method II, which is rela-
55.1 Determine the cold Rockwell hardness in accordance tively complex, allows more precise control of test conditions
with Test Method D785, except that under Method A use the M than Method I.
scale provided that the total indentation does not exceed the
61.3 Neither method will directly produce information from
limits of the testing machine. If the total indentation exceeds
which the performance of the insulating material in service can
the limits, use the L scale. Test four specimens.
be quantitatively predicted, since the conditions of use in
55.2 Determine the hot Rockwell hardness in accordance electrical apparatus are likely to be different than the test
with Test Method D785 and Test Method D617. Test four conditions. In this procedure, the specimens are subjected to
specimens. one or more specific sets of laboratory test conditions. If
different test conditions are substituted or the end-use condi-
ASH tions are changed, it is not always possible by or from this test
56. Significance and Use method to predict changes in the fire-test-response character-
istics measured. Therefore, the results are valid only for the fire
56.1 The nature and amount of ash is potentially useful in test exposure conditions described in this procedure.
determining the continuity of quality and in the interpretation
of results of tests for the purposes of design. 61.4 Both methods provide for the measurement of resis-
tance to ignition and resistance to continued burning. Method
57. Test Specimen I simply distinguishes between specimens that will ignite
57.1 The test specimen shall consist of 2 to 5 g of finely (under conditions of the test) from those that will not. Resis-
divided particles, such as millings or filings, of the material. tance to burning is determined by the time the specimen burns.
In Method II, it is possible to compare materials directly for
58. Procedure resistance to ignition by determination of ignition time and for
58.1 Dry the test specimen for 2 h at 105 to 110°C, weigh, burning by the burning time. The comparison of burning, or the
then ignite to constant weight in a crucible, and weigh. tendency of the material to contribute to the spread of fire,
Calculate the percentage of ash, based on the weight of the requires interpretation regardless of which method is used.
dried specimen. Some materials continue to burn for relatively long periods of
time without the dissipation of much heat energy. Other
59. Report materials burn for relatively shorter periods; however, it is
59.1 Report the following information: possible that they will burn with potentially damaging inten-
59.1.1 The identification of the sample tested, and sity. The determination of weight loss can aid in an interpre-
59.1.2 The percentage ash based on the dry weight of the tation of burning time test results on some materials and is an
specimen. additional option by agreement between producer and con-
sumer.
60. Precision and Bias
Flammability Method I
60.1 This test method has been in use for many years, but no
statement for precision has been made and no activity is 62. Apparatus
planned to develop such a statement.
62.1 Flame Cabinet—A draft-free enclosure, test chamber,
60.2 A statement of bias is not available because of the lack or hood equipped with an exhaust fan which is controlled by a
of a standard reference material for this property. readily-accessible switch.
IGNITABILITY AND BURNING TIME 62.2 Supports—A ring stand with a clamping device for
holding test specimens.
61. Significance and Use
62.3 Burner—A Tirrill burner having a tube length of 4 in.
61.1 Rigid electrical insulation is sometimes exposed to
(100 mm) and an inside diameter of 3⁄8 in. (9.5 mm). The tube
temperature sufficiently high to indicate a danger of ignition.
shall have no end attachments such as a flame stabilizer.
Potential reasons for this are: malfunction of the apparatus of
which the insulation is a part, failure of associated equipment 62.4 Gas Supply—A methane or natural gas supply having a
in the system, or failure of the insulation to resist ignition in heat content of approximately 1000 Btu/ft 3 (30 kJ/m3) and a
normal-usage exposure to electric arcs. It is therefore desirable suitable flow regulator.

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62.5 Timer—A timepiece or stop watch measuring seconds. TABLE 1 Laminate Method I Flammability Classes
Class 0 Class 1
62.6 Oven—A forced-ventilation oven maintained at 70 6 First application of flame:
1°C (158 6 1.8°F). Flaming time for single specimen, s 10 30
62.7 Desiccator—A desiccator containing anhydrous cal- Second application of flame:
cium chloride or equivalent desiccant. Maximum flaming time for a single specimen, s 10 30
Maximum flaming plus glowing time for a 30 60
single specimen, s
63. Test Specimens
Both applications of flame:
63.1 Dimensions of test specimens shall be 5 6 1⁄16 in. (12.7 Maximum total time of flaming combustion for five 50 250
6 1.6 mm) long by 0.56 0.02 in. (12.7 6 0.51 mm) wide by specimens in each flame application, s
the thickness of the sheet. The cut edges of the specimens shall
be smooth and free of projecting fibres.
63.2 Cut a total of 20 test specimens without regard to grain
direction (unless this is a variable being studied) and divide
into two sets of 10 specimens each. 66.1.1 Description of material tested, including thickness
and whether the sample was copper-clad, and
63.3 Test copper-clad specimens with the copper removed 66.1.2 The laminate shall be classed as Class 0 or Class 1 if
by etching in accordance with Practice D1825. the specimens for both conditioning procedures of Section 64
meet the requirements of Table 1.
64. Conditioning
64.1 Condition one set of 10 test specimens for at least 48 h Flammability Method II
at 23 6 2°C and 50 6 5 % relative humidity.
67. Apparatus
64.2 Condition the other set of 10 specimens for 168 h in an
oven at 70 6 1°C and then allow to cool for at least 4 h in a 67.1 Flame Cabinet—A metal cabinet with heater coil,
desiccator. spark gaps, specimen holder, access door, and forced-air
ventilation as illustrated in Fig. 5, or equipment that gives
65. Procedure equivalent results.
65.1 Support the test specimen with its 5-in. (128-mm) 67.2 Control Cabinet—A control assembly that provides
dimensional axis vertical and clamped within 1⁄4 in. (6.3 mm) adjustable, regulated power to the heater coils, ignition voltage
of the top at a height such that the lower free end is 3⁄8 in. (9.5 to the spark gaps, and a timer or timers to indicate the required
mm) above the top of the burner tube. time intervals as illustrated in Fig. 6.
65.2 With the burner removed from the specimen, ignite the 67.3 Pyrometer—An optical pyrometer calibrated to read
gas and adjust the flame until it is 3⁄4 in. (19.1 mm) high with directly for the emission of Nichrome V, or an optical pyrom-
a blue color and no yellow tip. eter calibrated for black-body emission to which 6°C is added
to the pyrometer reading to obtain the true temperature of the
65.3 For each conditioning procedure (see Section 64), test Nichrome V coil. The pyrometer shall include a scale for
one set of five specimens with the second set of five specimens measurement of temperature near 860°C.
held in reserve for retesting, if necessary (see 65.6).
67.4 Coil Form—A grooved mandrel on which the
65.4 Position the burner centrally below each specimen in Nichrome V resistance wire is wound into a heater coil as
the first set selected for each condition, allow to remain for 10 s illustrated in Fig. 7(a).
and then remove. Record the duration of flaming. When
flaming ceases immediately replace the burner flame under the 67.5 Coil Spacing Gauge—A spacing gauge constructed of
specimen for another 10-s interval and then remove. Again a sector of a coil form, as illustrated in Fig. 7(b) to check the
record the duration of flaming and of flaming plus glowing. coil turn-spacing.
65.5 Note if the specimen burns completely in either of the 68. Test Specimen
two flame applications. (A rating cannot be assigned to the
material in this case.) 68.1 The specimen shall be 1⁄2 6 0.036 in. (13 6 0.8 mm)
thick or nominal unmachined tolerance by 1⁄2 6 0.01 in. (13 6
65.6 If any one specimen in either set of five specimens for 0.25 mm) in width by 10 6 1⁄16 in. (254 6 1.6 mm) in length.
each condition fails to comply with the requirements given in In cases of molded products, the length of the specimen shall
Table 1, test a second set of five specimens for that condition. be permitted to be shorter.
With respect to the total number of seconds of flaming, test an
additional set of five specimens if the total is in the range from 68.2 Machine the specimens in a manner that produces a cut
51 to 55 s for Class 0 material or in the range from 251 to 255 s surface that is free of projecting fibers and ridges.
for Class 1 material. 68.3 The test sample consists of five test specimens.

66. Report 69. Calibration

66.1 Report the following information: 69.1 Place a dummy specimen in the holder.

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FIG. 5 Flame Cabinet

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FIG. 6 Electrical Diagram for Control Cabinet

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disturb test conditions when the test is performed with properly con-
structed apparatus. However, changing drafts are likely to disturb the
thermal equilibrium condition so that it is possible that the heater coil
temperature will change from the specified temperature even though
constant input power is supplied.

71. Procedure
71.1 After calibration is completed, use an air jet to cool the
coil to room temperature.
71.2 Insert the specimen in the holder with the cut side
facing the spark gaps. (When testing laminates, make the plane
of laminations parallel to the plane of the front of the
apparatus.) Close the peep-hole.
71.3 Move the arc electrodes to the horizontal position.
Energize the ventilating blower.
FIG. 7 Mandrel for Coil (a) and Coil Spacing Gauge (b) 71.4 Simultaneously energize the heater coil, arc gap, and
timer circuit.
69.2 Adjust the heater coil so that the bottom turn is 11⁄2 in. 71.5 Record the elapsed time in seconds when the test
(38 mm) above the top of the specimen holder, the coil is specimen ignites as ignition time, I.
symmetrical about the specimen, and the coil height is 11⁄2 in. 71.5.1 Ignition time is determined from the instant that the
(38 mm). Use the coil spacing gauge to adjust, if necessary, the specimen bursts into flame rather than from the instant of gas
individual coil turns for proper spacing. flame ignition.
69.3 Adjust the spark gap to 3⁄16 6 1⁄16 in. (5 6 1.6 mm) and 71.5.2 It is possible that gases released from the specimen
determine that the arc is in an approximate horizontal plane. will ignite before the specimen commences burning.
The total (in both electrodes) arc-current shall be 20 6 5 mA.
71.6 De-energize the heater and spark gaps 30 s after the
The electrode tips shall be approximately 1⁄8 in. (3 mm) in a
specimen ignites; move the arc electrodes away from the
horizontal plane from the specimen and 1⁄2 in. (13 mm) above
specimen.
the top turn of the heating coil.
69.4 Remove the dummy specimen. Close the door and 71.7 De-energize the timer circuit when the specimen
energize the ventilating blower. Energize the heating coil and ceases to burn (all flame has disappeared), and record the total
adjust the heater current to approximately 55 A. Allow the coil elapsed, T, in seconds.
to come to equilibrium temperature (approximately 120 s). If a 71.8 Before beginning the next test, cool the coil with an air
new coil is being used, reduce the current to 50 A and allow to jet, brush soot and contamination from the heater coil and arc
remain energized for 24 h to produce a stable oxide coating. gaps, and blow any debris from the test enclosure.
69.5 Open the peep-hole in the door; sight the optical
pyrometer on the outside of the middle turn and adjust the 72. Calculation
heater current to obtain an equilibrium temperature of 860 6 72.1 Burning Time—Calculate the burning time, B, in
5°C. Keep the peep-hole closed during test. seconds, as follows:
69.6 After the current has been adjusted, the variable-ratio B 5 T 2 I 2 30 (3)
autotransformer setting must not be disturbed during the test.
In order to maintain the temperature within 65°C, it is where:
necessary that the average rms voltage across the heater remain T = total elapsed time, and
constant within 61.0 %. I = ignition time.
Calculate the burning time by arranging the five values of
70. Conditioning burning time in increasing order of magnitude, as T1, T2, T3, T4,
70.1 Condition specimens for 168 h in the Standard Labo- and T5. Compute the following ratios:
ratory Atmosphere (23°C, 50 % relative humidity) except that ~ T 2 2 T 1! / ~ T 5 2 T 1!
when it is demonstrated that test results for the specific type
material are not significantly affected by conditioning, the use and
of unconditioned specimens is permitted.
~ T 5 2 T 4! / ~ T 5 2 T 1!
70.2 Conduct tests in a room that is controlled at the
Standard Laboratory Atmosphere (Note 4) and is free of If either of these ratios exceeds 0.642 then T1 or T5 is judged
spurious drafts (Note 5). to be abnormal and is eliminated. Report the burning time as
the average of the remaining four values.
NOTE 4—It is a well-established fact that the combustion process is
influenced by the moisture content of the oxygen-providing atmosphere. 72.2 Average Ignition Time—Calculate the average ignition
NOTE 5—Drafts, except those of unusual velocity, are not likely to time as the arithmetic mean of the five specimens.

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 D229 − 19´1
73. Report 79. Calculation
73.1 Report the following information: 79.1 Calculate the percentage warp or twist based on a
73.1.1 Nominal thickness of the test specimen, 36-in. (914-mm) length as follows:
73.1.2 Average and individual burning times and ignition W 914 5 ~ 914D/L 2 ! 3 100 (4)
times, and
or
73.1.3 Description of how the specimen burns with particu-
lar attention to the intensity of the flame. W 36 5 ~ 36D/L 2 ! 3 100 (5)
73.1.4 Burning time of each specimen and average burning where:
time. W914 = percentage warp or twist calculated to a 914-mm
73.1.5 Ignition time of each specimen and average ignition length, or
time. W36 = percentage warp or twist calculated to a 36-in.
length,
74. Precision and Bias D = maximum deviation in millimetres or inches of the
74.1 This test method has been in use for many years, but no sheet from the straight-edge, and
statement for precision has been made and no activity is L = length in millimetres or inches of the dimension
planned to develop such a statement. along which the warp or twist is measured.

74.2 A statement of bias is not available because of the lack 79.2 When it is desired to compare the actual deviation for
of a standard reference material for this property. any length with the permissible deviation for that length, use
the following equation:
COEFFICIENT OF LINEAR THERMAL EXPANSION D x ⁄ D 914 5 L x 2 ⁄ ~ 914! 2 (6)

75. Procedure or
D x ⁄ D 36 5 L x 2 ⁄ ~ 36! 2 (7)
75.1 Test a minimum of two specimens in accordance with
Test Method D696. where:
Dx = permissible deviation from straight-edge in milli-
WARP OR TWIST
metres or inches for the given length,
D914 = permissible deviation in millimetres for 914-mm
76. Significance and Use length, or
76.1 Warp and twist are expressions of deviation from D36 = permissible deviation in inches for 36-in. length, and
flatness of a material. The extent of deviation is of interest
primarily when it is intended to fabricate the sheet or plate Lx = given length in millimetres or inches.
material, but also has the potential to affect the ability to use NOTE 6—These requirements do not apply to cut pieces, but only to
sheet sizes as manufactured.
the full-size sheet in an assembly.
80. Report
77. Conditioning
80.1 Report the following information:
77.1 It is generally not necessary to condition the material. 80.1.1 The identification of the sample tested, and
Where conditions of storage have the potential to cause warp or 80.1.2 The percent warp or twist based on a 36-in. (914-
twist, condition the material in a manner agreed to by the mm) length.
purchaser and the supplier.
81. Precision and Bias
78. Procedure 81.1 This test method has been in use for many years, but no
78.1 Determine the warp or twist on the sheet in the statement for precision has been made and no activity is
as-received condition by holding a straightedge along the planned to develop such a statement.
dimension to be measured. Place the concave side of the sheet 81.2 A statement of bias is not available because of the lack
adjacent to the straightedge. Measure the greatest deviation of of a standard reference material for this property.
the concave surface from the straightedge by a metal scale.
ACETONE EXTRACTABLE MATTER
78.2 Warp—Measure the warp by suspending the sheet
freely from the center of one edge in a vertical position against 82. Procedure
a horizontal straightedge, then in succession by the other edges 82.1 Determine the acetone extractable matter in accor-
until the point of maximum warp is obtained. dance with Test Method D494.
78.3 Twist—Measure the twist by suspending the sheet in a
vertical position from adjacent corners, singly and in 83. Precision and Bias
succession, and then measuring the deviation along the diago- 83.1 It is important that duplicate determination by different
nal from the straightedge connecting the corners opposite from operators not differ by more than 6 0.5 % extractable matter
the vertical. Report the maximum twist. for values under 5.0 % and 61.0 % for values 5.0 to 12.0 %.

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 D229 − 19´1
83.2 This test method has no bias because the value for ability; impact resistance; insulation resistance; permittivity;
acetone extractable matter is determined solely in terms of this printed wiring boards; resistivity; rigid plates; rigid sheets;
test method. Rockwell hardness; solvent extractible; spacers; surface resis-
tance; surface resistivity; tensile strength; terminal boards;
84. Keywords
thermal expansion; thermosetting laminate; thickness; tracking
84.1 ac breakdown voltage; arc resistance; ash content; resistance; twist; voltage barriers; volume resistivity; warp;
bond strength; burning time; compressive strength; dissipation water absorption
factor; elastic modulus; flexural strength; hard rubber; ignit-

SUMMARY OF CHANGES

Committee D09 has identified the location of selected changes to this standard since the last issue (D229 – 13)
that may impact the use of this standard. (Approved March 1, 2019.)

(1) Revised 1.4. (5) Deleted Section 67 (and moved the definitions to Section
(2) Revised terminology section. 3). Renumbered subsequent sections accordingly.
(3) Revised 61.1 – 61.3. (6) Revised section on report of Flammability Method I.
(4) Revised titles of fire tests and of Table 1. (7) Revised keywords.

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