1、Designation: F3272 17Standard Guide forSelection, Care, and Use of Arc Protective Blankets1This standard is issued under the fixed designation F3272; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A numb
2、er in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides information for the selection, care,and use of arc protective blankets for personnel protection.1.2 This guide covers p
3、ositioning, and securing, arc protec-tive blankets (tested to Test Method F2676) and channeling thethermal, ballistic, and concussive forces generated by an arcflash event using arc protective blankets.1.3 This guide defines the use of the arc protective blanketto maximize its protective effectivene
4、ss to workers exposed toenergized electrical equipment where complete de-energizingof the work zone cannot be achieved or for low-risk exposureswith sufficient arc flash incident energy to warrant secondaryprotective means in the event of an arc flash.1.4 The values stated in SI units are to be rega
5、rded as thestandard. See IEEE/ASTM SI-10.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicabili
6、ty of regulatory limitations prior to use.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the Wor
7、ld Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D4391 Terminology Relating to The Burning Behavior ofTextilesF819 Terminology Relating to Electrical Protective Equip-ment for WorkersF2676 Test Method for Determining the Protective Perfor-ma
8、nce of an Arc Protective Blanket for Electric ArcHazards2.2 IEEE/ASTM Standard:2IEEE/ASTM SI-10 American National Standard for MetricPractice2.3 NFPA Standard:3NFPA 70E Standard for Electrical Safety in the Workplace2.4 CSA Standard:4CSA Z462 Workplace electrical safety2.5 OSHA Standards:529 CFR 191
9、0.269 Occupational Safety and Health Stan-dards: Special Industries29 CFR 1926.950-969 Safety and Health Regulations forConstruction3. Terminology3.1 Definitions:3.1.1 For definitions relating to the burning behavior oftextiles, see Terminology D4391 and for definitions relating toelectrical protect
10、ive equipment for workers, see TerminologyF819.3.1.2 abnormal condition, nabnormalities such as but notlimited to, oil or compound leaking from cable or joints,broken cable sheaths or joint sleeves, hot localized surfacetemperatures of cables or joints, or joints that are swollenbeyond normal tolera
11、nce are presumed to lead to or be anindication of an impending fault. Note: this term does notappear in the standard.3.1.3 anchoring, vmethod of physical attachment for se-curing the blanket and all attached components (straps,stanchions, other hardware, etc.) in place for the duration of theprotect
12、ion level for which the blanket is rated.3.1.4 blistered insulation, na condition in which electricalinsulation exhibits visible signs of thermal deformation usuallyexhibited as a bubble on the insulation.1This guide is under the jurisdiction of ASTM Committee F18 on ElectricalProtective Equipment f
13、or Workers and is the direct responsibility of SubcommitteeF18.65 on Wearing Apparel.Current edition approved Nov. 15, 2017. Published December 2017. DOI:10.1520/F3272-17.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Ann
14、ual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from National Fire Protection Association (NFPA), 1 BatterymarchPark, Quincy, MA 02169-7471, http:/www.nfpa.org.4Available from Canadian Standards Association (CSA), 178 Rexdale B
15、lvd.,Toronto, ON M9W 1R3, Canada, http:/www.csagroup.org.5Available from Occupational Safety and Health Administration (OSHA), 200Constitution Ave., NW, Washington, DC 20210, http:/www.osha.gov.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United
16、 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers t
17、o Trade (TBT) Committee.13.1.5 conduit channel type construction, nthis is a com-mon choice by many utilities because it is already widely usedin their systems and they are typically stock and coded itemsthat can be easily issued from company stores.3.1.5.1 DiscussionThe sizing and types of strut va
18、ry, buttypically it is 14-gauge with half-inch hardware construction orequivalent for concrete construction. Rated blanket attachmentstraps with rated carabineers are used to hold the blankets inplace. This construction method is also widely used when theintegrity of the vault wall is questionable a
19、nd the need tospread the load is necessary. So, longer pieces of strut are usedand more anchor bolts are used to attach it, thus spreading theload.3.1.6 fixed mechanical concrete anchor, nthis type ofanchor is produced in a variety of styles that includes standardfastening hardware and rated hardwar
20、e and may come withtorque indicators (shear bolts) notifying the user the anchor hasbeen installed properly.3.1.7 inverse square distance formula, nheat and concus-sive energy/force decreases generally as the square of thedistance.3.1.8 removable concrete anchor, nthis type of anchor isproduced in a
21、 variety of styles that include, but are not limitedto, D-ring anchors with and without friction sleeve boltattachments and are typically rated at 5000- and 10 000-lbs.(2268- and 4536-kg) maximum capacity.3.1.8.1 DiscussionThis type of anchor is quick and easy toinstall and can be reused, thus holdi
22、ng down hardware costs.4. Summary of Guide4.1 This guide provides background understanding forselection, care and use of arc protective blankets as tested byTest Method F2676. The guide is not a work practice and doesnot require blankets be used in the conditions described.4.2 The guide provides gui
23、dance users can use to informwork practices, development of blanket use schemes, and ideasfor testing efficacy of blanket configurations and practices.4.3 The guide is based on the collective knowledge of thecommittee, published practices of committee members, testing,and OSHA testimony in 29 CFR 19
24、10.269.5. Significance and Use5.1 This guide provides positioning, installation, and an-choring techniques that may be used to arrange arc protectiveblankets to confine or divert the energies found from a faultthat may include plasma arcing, pressure wave, and projectiles.5.2 Arc protective blankets
25、 may be used in any electricalapplication to confine or divert energy away from a work zonefor electrical or other workers who may be exposed to anelectric arc in the event of an equipment or conductor failure.5.3 Cables, splices, and any equipment components whichhave historical failures deemed to
26、require additional protectionor engineering controls which could benefit from added pro-tection provided by an arc protective blanket.5.4 This guide is designed for electrical engineers andqualified installers of arc protective blankets.5.5 The practice is limited by the blanket protective value,the
27、 sturdiness of the installation, and the engineering assump-tions of the hazard assessment.5.6 These blankets do not typically provide dielectric pro-tection.5.7 They do not eliminate the need for arc-rated PPE butmay reduce the level of the hazard in some installations.6. How Blankets Work to Help
28、Protect from Arc Flash6.1 An arc protective blanket is designed to direct heat,gases, and projectiles away from the worker. While the arcprotective blanket is tested to confine or divert an ejected arcup to the arc protective blanket breakopen threshold perfor-mance (BTP) level in the rating. It is
29、always safer to channelenergy away from the workers rather than challenge the energy.For example, putting slack in the center at the top of theblanket to allow the energy to be directed above the blanketmay be more protective in some scenarios.6.2 Tension in testing ensures full, worst case exposure
30、 toarc (The blanket is installed like a trampoline). This installationmethod is typically used only when installing the blanket likea wall. Installing blankets with other methods typically willallow better performance of the blanket but may compromisethe area protected by the blanket by diverting th
31、e energy.Energy diversion away from workers is a key method to use inblanket installation. Some allowance for blanket movementaway from arc can allow for greater protection.6.3 Some blankets have a sidedness and the marked sideshould always be installed as recommended by the manufac-turer.7. Install
32、ation Practices7.1 General:7.1.1 Choose a blanket with a maximum rating greater thanthe predicted fault current at the location. Exceeding theblanket rating or failure to secure the blanket by the method astested may result in failure to completely protect or providelimited or no protection.7.1.2 Us
33、e the largest blanket that will fit into the availablespace.7.1.3 Use the attachments provided by or required by themanufacturer which are typically flame resistant. If connectingmeans do not use manufacturers connecting means, ensure theefficacy of the connecting means. This is typically donethroug
34、h testing.7.1.4 Install the top of blankets at a height ideally above theworkers head in a work situation to allow energy to bediverted above the workers head. Secure the blanket at the topto prevent energy diverting into the area of the face.NOTE 1Typically, a workers head may not be as well protec
35、ted as thetorso. This is not typically true of an arc flash suit which has moreprotection on the torso than the legs.NOTE 2When wrapping or installing in a horizontal, planarinstallation, tools, equipment, or parts placed on a blanket could be ejectedin the event of a failure.7.1.5 Match the blanket
36、 to the worst case fault current andpredicted clearing time using the BTP of the blanket and theF3272 172maximum rated current of the blanket. Use of a blanket beyondits maximum fault current or its maximum BTP may haveunintended effects such as complete blanket failure or exten-sive after flame of
37、the blanket. In an enclosed area, this effectcan be dangerous. Some blankets may have deleterious effectsat higher levels but this is typically not discernable by testresults. Contact the manufacturer for guidance on blanket usein unusual conditions (oil-filled cables or breakers, higher faultcurren
38、ts, enclosed spaces, etc.)7.1.6 Disturbing energized electrical equipment, especiallycables and cable splices, can cause an arc flash. Exercise bestpractices when installing blankets for worker protection.7.1.7 Engineering a blanket installation by using distancefrom the exposure, electrode geometry
39、, the clearing time, andother applicable factors would be acceptable.7.1.8 The complexity and arrangement of cable, cablesplices, and other energized equipment; the variety of vaultspace, purpose, and configuration; the composition of eachspaces infrastructure; the wide variety of hardware used toho
40、ld and secure electrical components and devices foundtherein; and the deterioration exerted, as a result of bothelectrical and environmental stress, may require the use ofmore than one anchoring and shielding method outlined in thisguide.7.1.9 Stations, straps and buckles, carabiners, lugs, andother
41、 items which blankets are installed onto can become ahazard if they cannot withstand the pressure from the arc fault.7.2 Shielding Methods:7.2.1 “J” Type ShieldingThe “J” Type installation (Fig. 1)is so named because, upon placement of the blanket in front ofthe racks and splices, the bottom of the
42、blanket is tucked backtoward the vault wall and the top is arrayed in a “D” shape withthe middle of the blanket bowed out so that the completedarrangement looks much like a sail. The potential arc blast isnot allowed under the blanket and its energy is channeled awayfrom the worker around the sides
43、and up over the workershead IF the installation is tall enough. Other applications mayuse the “J” installation when it is desirable to shunt energyupward. The straps at the top will be looser than those on thesides in this installation.7.2.2 Clamshell “C”Individual splices may be enclosedusing a cla
44、mshell type installation to shunt energy out the endsof the blanket or individual splice and prevent exposure to theworker.7.2.2.1 This method may be used over a wrapped blanket asan additional protective layer and anchored top and bottom tothe back of the vault wall with the open end of the “C” sha
45、pepointed to the vault wall (Figs. 2-4). The intent is to channel theenergy sideways away from the worker and, since the firstwrapped blanket is lying directly on the splice, this secondblanket system is arrayed as a precaution. This also preventsthe wrapped blanket from dislodging and hitting worke
46、rs.7.2.2.2 Use extra attention when using this method to ensureno contact with energized parts and to prevent allowing metalor carabiners to contact energized parts.7.2.3 Suspended Blanket WallThis method was developedas part of the test method and used by some utilities. A devicemade of steel pipin
47、g that is assembled in the vault and attachedto screw jacks (Fig. 5). The jacks are tightened exertingpressure on the ends and, thus, holding the structure in placeand a blanket is attached to these stanchions creating a barrierwall. It can be used against the vault wall or away from it.Creating a c
48、lean and secure surface for the pressure pads is achallenge but, in testing it has performed well in the test vaultincluding the management of 40kA/10-cycle shots. However,in some applications, it has proven to be difficult to get thepiping pieces into the manhole or vault.7.2.3.1 A variation of thi
49、s may be a permanent installation(see Fig. 6).7.2.3.2 This is a variation of the “J” installation.7.2.3.3 Stanchions if not tested, installed, and designed towithstand the blast pressure of the arc can become a hazard.7.2.4 Arc Cube Method (Fig. 7)This method uses adielectric cube installed in place around the worker position toshield the worker from an arc flash while leaving all equipmentFIG. 1 “J” Type ShieldingNOTE 1Straps and anchors are not shown.FIG. 2 Clamshell with Wrapped Cable SpliceF3272 173in place. This method does not use preinstalled anchors
