ASTM D1048-14(2019)
(Specification)Standard Specification for Rubber Insulating Blankets
Standard Specification for Rubber Insulating Blankets
ABSTRACT
This specification covers the acceptance testing of insulating rubber blankets that are used for the personal protection of workers from accidental contact with live electrical conductors, apparatus, or circuits. Two types of blankets, differing in chemical and physical characteristics, are provided and are designated as: Type I, made from properly vulcanized high-grade cis-1,4-polyisoprene rubber compound of natural or synthetic origin that is non-resistant to ozone; and Type II, made of any elastomer or combination of elastomeric compounds that is resistant to ozone. Five classes of blankets, designated as Classes 0, 1, 2, 3, and 4, are assigned according to electrical protection characteristics. Styles of blankets are designated in accordance to construction characteristics, namely: Style A, blankets free of any reinforcements; and Style B, blankets incorporated with reinforcement(s). When evaluated in accordance with the test procedures detailed herein, the blankets shall adhere to the following property requirements: electrical properties such as phase-phase maximum use voltage, AC and DC proof-test voltages, AC and DC dielectric breakdown test voltages, and AC and DC clearances; and physical and chemical properties such as ozone resistance, moisture absorption, tensile strength, tension set, elongation, drape stiffness, flex stiffness, tear resistance, resistance to accelerated heat aging, and puncture resistance.
SCOPE
1.1 This specification covers acceptance testing of rubber insulating blankets for protection of workers from accidental contact with live electrical conductors, apparatus, or circuits.
1.2 Two types of blankets are provided and are designated as Type I, not resistant to ozone, and Type II, resistant to ozone.
1.3 Five classes of blankets, differing in electrical characteristics, are provided and are designated as Class 0, Class 1, Class 2, Class 3, and Class 4.
1.4 Two styles of blankets, differing in construction characteristics, are provided and are designated as Style A and Style B.
1.5 The following safety hazards caveat pertains only to the test method portion, Sections 16 – 19, of this specification: This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.6 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.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D1048 −14 (Reapproved 2019)
Standard Specification for
Rubber Insulating Blankets
This standard is issued under the fixed designation D1048; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope D297Test Methods for Rubber Products—ChemicalAnaly-
sis
1.1 This specification covers acceptance testing of rubber
D412TestMethodsforVulcanizedRubberandThermoplas-
insulating blankets for protection of workers from accidental
tic Elastomers—Tension
contact with live electrical conductors, apparatus, or circuits.
D518 Test Method for Rubber Deterioration—Surface
1.2 Two types of blankets are provided and are designated
Cracking (Withdrawn 2007)
asTypeI,notresistanttoozone,andTypeII,resistanttoozone.
D570Test Method for Water Absorption of Plastics
D573Test Method for Rubber—Deterioration in an Air
1.3 Five classes of blankets, differing in electrical
characteristics, are provided and are designated as Class 0, Oven
D624Test Method for Tear Strength of Conventional Vul-
Class 1, Class 2, Class 3, and Class 4.
canized Rubber and Thermoplastic Elastomers
1.4 Two styles of blankets, differing in construction
D1388Test Method for Stiffness of Fabrics
characteristics, are provided and are designated as StyleAand
D2865Practice for Calibration of Standards and Equipment
Style B.
for Electrical Insulating Materials Testing
1.5 The following safety hazards caveat pertains only to the
F819Terminology Relating to Electrical Protective Equip-
testmethodportion,Sections16–19,ofthisspecification: This
ment for Workers
standard does not purport to address all of the safety concerns,
2.2 American National Standards:
if any, associated with its use. It is the responsibility of the user
ANSI/IEEE C 2National Electrical Safety Code
of this standard to establish appropriate safety, health, and
C84.1Electric Power Systems and Equipment—Voltage
environmental practices and determine the applicability of
Ratings (60 Hz)
regulatory limitations prior to use.
1.6 This international standard was developed in accor-
3. Terminology
dance with internationally recognized principles on standard-
3.1 beaded edge—a narrow border of thicker rubber which
ization established in the Decision on Principles for the
extends completely around the outer edges of the blanket.
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3.2 breakdown—the electrical discharge or arc occurring
Barriers to Trade (TBT) Committee.
betweentheelectrodesandthroughtheequipmentbeingtested.
3.3 designated person—an individual who is qualified by
2. Referenced Documents
experience or training to perform an assigned task.
2.1 ASTM Standards:
3.4 electrical testing facility—a location with qualified
D149Test Method for Dielectric Breakdown Voltage and
personnel,testingequipment,andproceduresfortheinspection
DielectricStrengthofSolidElectricalInsulatingMaterials
and electrical testing of electrical insulating protective equip-
at Commercial Power Frequencies
ment.
1 3.5 electrode clearance—the shortest path from the ener-
This specification is under the jurisdiction of ASTM Committee F18 on
Electrical Protective Equipment for Workers and is the direct responsibility of gized electrode to the ground electrode.
Subcommittee F18.25 on Insulating Cover-Up Equipment. This standard replaces
ANSI Standard J6.4, which is no longer available.
Current edition approved April 1, 2019. Published April 2019. Originally
approved in 1949 as D1048–49 T. Last previous edition approved in 2014 as The last approved version of this historical standard is referenced on
D1048-14. DOI: 10.1520/D1048-14R19. www.astm.org.
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE),
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org.
Standards volume information, refer to the standard’s Document Summary page on Available from National Electrical Manufacturers Association (NEMA), 1300
the ASTM website. N. 17th St., Suite 900, Arlington, VA 22209, http://www.nema.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1048−14 (2019)
3.6 flashover—the electrical discharge or arc occurring be- turer and the detailed procedures by which such properties are
tween electrodes and over or around, but not through, the to be determined.The purchaser may, at his option, perform or
equipment being tested. have performed any of these tests in order to verify the
guarantee. Claims for failure to meet the specification are
3.7 insulated—separated from other conducting surfaces by
subject to verification by the manufacturer.
a dielectric substance (including air space) offering a high
resistance to the passage of current. 4.2 Blankets are used for personal protection; therefore,
3.7.1 Discussion—Whenanyobjectissaidtobeinsulated,it whenauthorizingtheiruse,amarginofsafetyshallbeprovided
is understood to be insulated in a suitable manner for the
between the maximum voltage at which they are used and the
conditions to which it is subjected. Otherwise, it is, within the proof-test voltage at which they are tested. The relationship
purpose of this definition, uninsulated. Insulating covering of
between proof-test voltage and the nominal maximum voltage
conductors is one means of making this conductor insulated. at which blankets shall be used is shown in Table 1.
3.8 ozone—a very active form of oxygen that may be
4.3 Work practices vary from user to user depending upon
produced by corona, arcing, or ultra-violet rays. manyfactors.Thesefactorsmayinclude,butarenotlimitedto,
operating system voltages, construction design, work proce-
3.9 ozone cutting and checking —cracksproducedbyozone
dures and techniques, weather conditions, etc. Therefore,
in a material under mechanical stress.
exceptfortherestrictionssetforthinthisspecificationbecause
3.10 rubber—a generic term that includes elastomers and
of design limitations, the use and maintenance of this equip-
elastomer compounds regardless of origin.
ment is beyond the scope of this specification.
3.11 user—theemployerorentitypurchasingtheequipment
4.3.1 Itiscommonpracticeandtheresponsibilityoftheuser
to be utilized by workers for their protection; in the absence of
of this type of protective equipment to prepare complete
such an employer or entity, the individual purchasing or
instructions and regulations to govern the correct and safe use
utilizing the protective equipment.
of such equipment.
3.12 voltage, maximum retest—voltage, either ac rms or dc
5. Classification
avg, that is equal to the proof-test voltage for new protective
5.1 Blankets covered under this specification shall be des-
equipment.
ignated asType I orType II; Class 0, Class 1, Class 2, Class 3,
3.13 voltage, retest—voltage, either ac rms or dc avg, that
or Class 4; Style A or Style B.
usedprotectiveequipmentmustbecapableofwithstandingfor
5.1.1 Type I,non-resistanttoozone,madefromahigh-grade
a specified test period without breakdown.
cis-1,4-polyisoprene rubber compound of natural or synthetic
3.14 voltage, nominal design—a nominal value consistent
origin, properly vulcanized.
with the latest revision ofANSI C84.1, assigned to the circuit
5.1.2 Type II, ozone resistant, made of any elastomer or
or system for the purpose of conveniently designating its
combination of elastomeric compounds.
voltage class.
5.1.3 The class designation shall be based on the electrical
3.15 voltage, maximum use—the ac voltage, (rms), classifi- properties as shown in Table 1 and Table 2.
5.1.4 Style A, constructed of the elastomers indicated under
cation of the protective equipment that designates the maxi-
mum nominal design voltage of the energized system that may Type I or Type II, shall be free of any reinforcement.
5.1.5 Style B, constructed of the elastomers indicated under
be safely worked. The nominal design voltage is equal to
phase-to-phase voltage on multiphase circuits. Type I or Type II, shall incorporate a reinforcement; this
reinforcement shall not adversely affect the dielectric charac-
3.15.1 If there is no multiphase exposure in a system area,
and the voltage exposure is limited to phase (polarity on dc teristics of the blankets.
systems) to ground potential, the phase (polarity on dc sys-
6. Ordering Information
tems)togroundpotentialshallbeconsideredtobethenominal
design voltage.
6.1 Orders for blankets under this specification should
3.15.2 If electrical equipment and devices are insulated or
include the following information:
isolated, or both, such that the multiphase exposure on a
grounded wye circuit is removed, then the nominal design
TABLE 1 Proof-Test/Use Voltage Relationship
voltage may be considered as the phase-to-ground voltage on
Nominal Maximum
that circuit.
A
Class of Insu- AC Proof-Test DC Proof-Test
Use Voltage
lating Blankets Phase-Phase, ac, Voltage, rms V Voltage, avg, V
NOTE 1—The work practices and methods associated with removing
rms, max
multiphase exposures at any given work site are not addressed in this
0 1 000 5 000 20 000
specification. Users should refer to ANSI C2, National Electrical Safety
1 7 500 10 000 40 000
Code, Section 44, for proper work practices.
2 17 000 20 000 50 000
3.16 For definitions of other terms, refer to Terminology 3 26 500 30 000 60 000
4 36 000 40 000 70 000
F819.
A
Except for Class O equipment, the maximum use voltage is based on the
4. Significance and Use
following formula:
Maximum use voltage (maximum nominal design voltage) 0.95 ac proof-test
4.1 This specification covers the minimum electrical,
voltage − 2000
chemical, and physical properties guaranteed by the manufac-
D1048−14 (2019)
TABLE 2 Electrical Proof-Tests
AC DC
Nominal Electrode Nominal Electrode
Proof-Test Voltage,
B
Class
A A
Proof-Test Voltages,
Clearances Clearances
rms,
avg, V
V
mm in. mm in.
0 5 000 76 3 20 000 76 3
1 10 000 76 3 40 000 76 3
2 20 000 127 5 50 000 152 6
3 30 000 178 7 60 000 203 8
4 40 000 254 10 70 000 305 12
A
These nominal clearances are intended to avoid flashover and may be increased by no more than 51 mm (2 in.) when required by a change in atmospheric conditions
from the standard of 100 kPa (1 atm) barometric pressure and average humidity conditions. These clearances may be decreased if atmospheric conditions permit.
B
DC proof-test voltages were determined using negative polarity.
TABLE 3 Physical Requirements
6.1.1 Type,
Type I Type II
6.1.2 Class,
Style A Style B Style A
6.1.3 Style,
Blanket Blanket Blanket
6.1.4 Size,
Tensile strength, min, Die C, 17.2 (2500) 17.2 (2500) 10.3 (1500)
6.1.5 Eyelets, and
MPa (psi)
Elongation, min, % 500 500 500
6.1.6 Color.
Tension set, max, mm (in.) 6.4 (0.25) 6.4 (0.25) 6.4 (0.25)
6.2 The listing of types, classes, styles, sizes, and eyelets is Tear resistance, min, kN/m 21 (120) 26 (150) 16 (90)
(lbf/in.)
notintendedtomeanthatallshallnecessarilybeavailablefrom
Puncture resistance, min, 18 (100) 26 (150) 18 (100)
manufacturers; it signifies only that, if made, they shall
kN/m (lbf/in.)
conform to the details of this specification. Drape stiffness, max at 89 (3.5) 89 (3.5) 89 (3.5)
25°C (77°F), mm (in.)
Drape stiffness, max at 110 (4.5) 110 (4.5) 110 (4.5)
7. Manufacture and Marking
−10°C (14°F), mm (in.)
Flex stiffness, max at 25°C 0.028 (0.25) 0.028 (0.25) 0.028 (0.25)
7.1 The blankets shall be produced by a seamless vulcaniz-
(77°F), N·m (in.·lbf)
ing process.
Flex stiffness, max at − 10°C 0.034 (0.30) 0.034 (0.30) 0.034 (0.30)
(14°F), N·m (in.·lbf)
7.2 Where eyelets are specified, each blanket shall be
Moisture absorption, max, % 1.5 3.0 2.0
equipped with nonmetallic eyelets.
7.3 Each blanket shall be marked clearly and permanently
with the name of the manufacturer or supplier,ASTM D1048,
9. Electrical Requirements
type, class, and style.
9.1 Each blanket shall be given a proof test and shall
7.3.1 Blankets may be marked by either molding the infor-
withstandthe60-Hzacproof-testvoltage(rmsvalue)orthedc
mation directly into the blanket or by use of a label; either
proof-test voltage (average value) specified in Table 2. The
method is equally acceptable. The method shall be at the
proof test shall be performed in accordance with Section 18
discretion of the manufacturer. If a label is used the color shall
and shall be conducted continuously for at least 3 min.
be that specified for each voltage class; Class 0—red, Class
1—white, Class 2—yellow, Class 3—green, and Class
9.2 The blanket material shall show a 60-Hz dielectric
4—orange.
strength of not less than 14.8 MV/m (375 V-rms/mil) of
specimen thickness for each individual test, when tested in
7.4 Blankets shall have a smooth, flat finish and beaded
accordance with 18.5.
edges.
10. Dimensions and Permissible Variations
8. Chemical and Physical Requirements
10.1 Length and Width—The length and width of the blan-
8.1 The blanket material shall conform to the physical
kets shall be specified on the purchase order. Some standard
requirements in Table 3 and the accelerated aging in 19.2.7.
8.2 For Type I blankets, the rubber polymer may be deter-
mined in accordance with 19.1.1. This shall be the referee test TABLE 4 Standard Blanket Sizes—Length and Width
if a dispute exists between the manufacturer and purchaser
Without Slot mm (in.)
457 by 910 (18 by 36)
regarding the elastomer content of Type I blankets.
560 by 560 (22 by 22)
8.3 The Type II blanket material shall show no visible 690 by 910 (27 by 36)
910 by 910 (36 by 36)
effects from ozone when tested in accordance with 18.6. Any
910 by 2128 (36 by 84)
visible signs of ozone deterioration, such as checking,
1160 by 1160 (45.5 by 45.5)
cracking, breaks, pitting, etc., shall be considered as evidence With Slot mm (in.)
560 by 560 (22 by 22)
of failure to meet the requirements ofType II blankets. In case
910 by 910 (36 by 36)
of dispute, Method A of the ozone resistance test shall be the
1160 by 1160 (45.5 by 45.5)
referee test.
D1048−14 (2019)
sizes are as shown in Table 4. Permissible variations from the binding on the manufacturer or supplier only if the blankets
specified length and width shall be 613 mm (60.5 in.) except havebeenproperlystoredandhavenotbee
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D1048 − 14 D1048 − 14 (Reapproved 2019)
Standard Specification for
Rubber Insulating Blankets
This standard is issued under the fixed designation D1048; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This specification covers acceptance testing of rubber insulating blankets for protection of workers from accidental contact
with live electrical conductors, apparatus, or circuits.
1.2 Two types of blankets are provided and are designated as Type I, not resistant to ozone, and Type II, resistant to ozone.
1.3 Five classes of blankets, differing in electrical characteristics, are provided and are designated as Class 0, Class 1, Class 2,
Class 3, and Class 4.
1.4 Two styles of blankets, differing in construction characteristics, are provided and are designated as Style A and Style B.
1.5 The following safety hazards caveat pertains only to the test method portion, Sections 16 – 19, of this specification: This
standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user
of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine the applicability
of regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
D149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at
Commercial Power Frequencies
D297 Test Methods for Rubber Products—Chemical Analysis
D412 Test Methods for Vulcanized Rubber and Thermoplastic Elastomers—Tension
D518 Test Method for Rubber Deterioration—Surface Cracking (Withdrawn 2007)
D570 Test Method for Water Absorption of Plastics
D573 Test Method for Rubber—Deterioration in an Air Oven
D624 Test Method for Tear Strength of Conventional Vulcanized Rubber and Thermoplastic Elastomers
D1388 Test Method for Stiffness of Fabrics
D2865 Practice for Calibration of Standards and Equipment for Electrical Insulating Materials Testing
F819 Terminology Relating to Electrical Protective Equipment for Workers
2.2 American National Standards:
ANSI/IEEE C 2 National Electrical Safety Code
C84.1 Electric Power Systems and Equipment—Voltage Ratings (60 Hz)
This specification is under the jurisdiction of ASTM Committee F18 on Electrical Protective Equipment for Workers and is the direct responsibility of Subcommittee
F18.25 on Insulating Cover-Up Equipment. This standard replaces ANSI Standard J 6.4, which is no longer available.
Current edition approved Nov. 1, 2014April 1, 2019. Published December 2014April 2019. Originally approved in 1949 as D1048 – 49 T. Last previous edition approved
in 20122014 as D1048-12.-14. DOI: 10.1520/D1048-14.10.1520/D1048-14R19.
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 Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE), 445 Hoes Ln., P.O. Box 1331, Piscataway, NJ 08854-1331, http://www.ieee.org.
Available from National Electrical Manufacturers Association, Association (NEMA), 1300 North 17th Street, Rosslyn, VA 22209.N. 17th St., Suite 900, Arlington, VA
22209, http://www.nema.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1048 − 14 (2019)
3. Terminology
3.1 beaded edge—a narrow border of thicker rubber which extends completely around the outer edges of the blanket.
3.2 breakdown—the electrical discharge or arc occurring between the electrodes and through the equipment being tested.
3.3 designated person—an individual who is qualified by experience or training to perform an assigned task.
3.4 electrical testing facility—a location with qualified personnel, testing equipment, and procedures for the inspection and
electrical testing of electrical insulating protective equipment.
3.5 electrode clearance—the shortest path from the energized electrode to the ground electrode.
3.6 flashover—the electrical discharge or arc occurring between electrodes and over or around, but not through, the equipment
being tested.
3.7 insulated—separated from other conducting surfaces by a dielectric substance (including air space) offering a high resistance
to the passage of current.
3.7.1 Discussion—When any object is said to be insulated, it is understood to be insulated in a suitable manner for the conditions
to which it is subjected. Otherwise, it is, within the purpose of this definition, uninsulated. Insulating covering of conductors is one
means of making this conductor insulated.
3.8 ozone—a very active form of oxygen that may be produced by corona, arcing, or ultra-violet rays.
3.9 ozone cutting and checking —cracks produced by ozone in a material under mechanical stress.
3.10 rubber—a generic term that includes elastomers and elastomer compounds regardless of origin.
3.11 user—the employer or entity purchasing the equipment to be utilized by workers for their protection; in the absence of such
an employer or entity, the individual purchasing or utilizing the protective equipment.
3.12 voltage, maximum retest—voltage, either ac rms or dc avg, that is equal to the proof-test voltage for new protective
equipment.
3.13 voltage, retest—voltage, either ac rms or dc avg, that used protective equipment must be capable of withstanding for a
specified test period without breakdown.
3.14 voltage, nominal design—a nominal value consistent with the latest revision of ANSI C84.1, assigned to the circuit or
system for the purpose of conveniently designating its voltage class.
3.15 voltage, maximum use—the ac voltage, (rms), classification of the protective equipment that designates the maximum
nominal design voltage of the energized system that may be safely worked. The nominal design voltage is equal to phase-to-phase
voltage on multiphase circuits.
3.15.1 If there is no multiphase exposure in a system area, and the voltage exposure is limited to phase (polarity on dc systems)
to ground potential, the phase (polarity on dc systems) to ground potential shall be considered to be the nominal design voltage.
3.15.2 If electrical equipment and devices are insulated or isolated, or both, such that the multiphase exposure on a grounded
wye circuit is removed, then the nominal design voltage may be considered as the phase-to-ground voltage on that circuit.
NOTE 1—The work practices and methods associated with removing multiphase exposures at any given work site are not addressed in this specification.
Users should refer to ANSI C2, National Electrical Safety Code, Section 44, for proper work practices.
3.16 For definitions of other terms, refer to Terminology F819.
4. Significance and Use
4.1 This specification covers the minimum electrical, chemical, and physical properties guaranteed by the manufacturer and the
detailed procedures by which such properties are to be determined. The purchaser may, at his option, perform or have performed
any of these tests in order to verify the guarantee. Claims for failure to meet the specification are subject to verification by the
manufacturer.
4.2 Blankets are used for personal protection; therefore, when authorizing their use, a margin of safety shall be provided
between the maximum voltage at which they are used and the proof-test voltage at which they are tested. The relationship between
proof-test voltage and the nominal maximum voltage at which blankets shall be used is shown in Table 1.
4.3 Work practices vary from user to user depending upon many factors. These factors may include, but are not limited to,
operating system voltages, construction design, work procedures and techniques, weather conditions, etc. Therefore, except for the
restrictions set forth in this specification because of design limitations, the use and maintenance of this equipment is beyond the
scope of this specification.
4.3.1 It is common practice and the responsibility of the user of this type of protective equipment to prepare complete
instructions and regulations to govern the correct and safe use of such equipment.
D1048 − 14 (2019)
TABLE 1 Proof-Test/Use Voltage Relationship
Nominal Maximum
A
Class of Insu- AC Proof-Test DC Proof-Test
Use Voltage
lating Blankets Phase-Phase, ac, Voltage, rms V Voltage, avg, V
rms, max
0 1 000 5 000 20 000
1 7 500 10 000 40 000
2 17 000 20 000 50 000
3 26 500 30 000 60 000
4 36 000 40 000 70 000
A
Except for Class O equipment, the maximum use voltage is based on the
following formula:
Maximum use voltage (maximum nominal design voltage) 0.95 ac proof-test
voltage − 2000
5. Classification
5.1 Blankets covered under this specification shall be designated as Type I or Type II; Class 0, Class 1, Class 2, Class 3, or Class
4; Style A or Style B.
5.1.1 Type I, non-resistant to ozone, made from a high-grade cis-1,4-polyisoprene rubber compound of natural or synthetic
origin, properly vulcanized.
5.1.2 Type II, ozone resistant, made of any elastomer or combination of elastomeric compounds.
5.1.3 The class designation shall be based on the electrical properties as shown in Table 1 and Table 2.
5.1.4 Style A, constructed of the elastomers indicated under Type I or Type II, shall be free of any reinforcement.
5.1.5 Style B, constructed of the elastomers indicated under Type I or Type II, shall incorporate a reinforcement; this
reinforcement shall not adversely affect the dielectric characteristics of the blankets.
6. Ordering Information
6.1 Orders for blankets under this specification should include the following information:
6.1.1 Type,
6.1.2 Class,
6.1.3 Style,
6.1.4 Size,
6.1.5 Eyelets, and
6.1.6 Color.
6.2 The listing of types, classes, styles, sizes, and eyelets is not intended to mean that all shall necessarily be available from
manufacturers; it signifies only that, if made, they shall conform to the details of this specification.
7. Manufacture and Marking
7.1 The blankets shall be produced by a seamless vulcanizing process.
7.2 Where eyelets are specified, each blanket shall be equipped with nonmetallic eyelets.
7.3 Each blanket shall be marked clearly and permanently with the name of the manufacturer or supplier, ASTM D1048, type,
class, and style.
7.3.1 Blankets may be marked by either molding the information directly into the blanket or by use of a label; either method
is equally acceptable. The method shall be at the discretion of the manufacturer. If a label is used the color shall be that specified
for each voltage class; Class 0—red, Class 1—white, Class 2—yellow, Class 3—green, and Class 4—orange.
TABLE 2 Electrical Proof-Tests
AC DC
Nominal Electrode Nominal Electrode
Proof-Test Voltage,
Class B
A A
Proof-Test Voltages,
Clearances Clearances
rms,
avg, V
V
mm in. mm in.
0 5 000 76 3 20 000 76 3
1 10 000 76 3 40 000 76 3
2 20 000 127 5 50 000 152 6
3 30 000 178 7 60 000 203 8
4 40 000 254 10 70 000 305 12
A
These nominal clearances are intended to avoid flashover and may be increased by no more than 51 mm (2 in.) when required by a change in atmospheric conditions
from the standard of 100 kPa (1 atm) barometric pressure and average humidity conditions. These clearances may be decreased if atmospheric conditions permit.
B
DC proof-test voltages were determined using negative polarity.
D1048 − 14 (2019)
7.4 Blankets shall have a smooth, flat finish and beaded edges.
8. Chemical and Physical Requirements
8.1 The blanket material shall conform to the physical requirements in Table 3 and the accelerated aging in 19.2.7.
8.2 For Type I blankets, the rubber polymer may be determined in accordance with 19.1.1. This shall be the referee test if a
dispute exists between the manufacturer and purchaser regarding the elastomer content of Type I blankets.
8.3 The Type II blanket material shall show no visible effects from ozone when tested in accordance with 18.6. Any visible signs
of ozone deterioration, such as checking, cracking, breaks, pitting, etc., shall be considered as evidence of failure to meet the
requirements of Type II blankets. In case of dispute, Method A of the ozone resistance test shall be the referee test.
9. Electrical Requirements
9.1 Each blanket shall be given a proof test and shall withstand the 60-Hz ac proof-test voltage (rms value) or the dc proof-test
voltage (average value) specified in Table 2. The proof test shall be performed in accordance with Section 18 and shall be
conducted continuously for at least 3 min.
9.2 The blanket material shall show a 60-Hz dielectric strength of not less than 14.8 MV/m (375 V-rms/mil) of specimen
thickness for each individual test, when tested in accordance with 18.5.
10. Dimensions and Permissible Variations
10.1 Length and Width—The length and width of the blankets shall be specified on the purchase order. Some standard sizes are
as shown in Table 4. Permissible variations from the specified length and width shall be 613 mm (60.5 in.) except for the 1160
by 1160-mm (45.5 by 45.5-in.) slotted size for which the permissible variation shall be 625 mm (61.0 in.).
10.2 Thickness—See Table 5.
10.2.1 Manufacturers must meet the minimum thickness requirements for each Class of blanket as specified in Table 5. The
manufacturer may label a blanket lower than actual Class value if so specified by the purchaser.
10.3 Bead on Edge— The bead shall be not less than 8 mm (0.31 in.) wide nor less than 1.5 mm (0.06 in.) high.
10.4 Eyelets—If other than manufacturer’s standard is desired; the number, size, and type of eyelet shall be given on the
purchase order. The
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