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| Arc
Ratings |
| Arc
ratings are values that indicate the arc performance of a material or system
of materials and are expressed in calories per centimeter squared. This
value may be either Arc Thermal Performance Value (ATPV) or Breakopen Threshold
Energy (EBT), depending on whether or not sufficient energy was transmittied
through the material to cause a second degree burn in human tissue before
the material broke open. Arc Rating s are statistical calculations based
on evaluation of a minimum of 20 data points generated in arc testing. With
advances in test methods and testing methodology , new data is constantly
being generated. |
ASTM
F1506 Standard Performance Specification for Textile Materials for Wearing
Apparel for Use by Electrical Workers Exposed to Momentary Electric Arc
and Related Thermal Hazards
This specification provides performance requirements for clothing worn by
electric utility workers and other personnel working around energized parts.
In addition to non-thermal requirements, the standard requires the fabric
to be flame-resistant; that is, to not ignite and continue to burn after
exposure to an ignition source. Flame resistance is measured using FTM 5903.1
Vertical Flame test (max. 2 sec afterflame and 6 in. char length). The standard
is currently being revised to include the requirement of reporting an Arc
Rating. The Arc Rating is either the Arc Thermal Performance Value (ATPV)
or Arc Breakopen Value (EBT) as measured by ASTM F1959 Arc Thermal Performance
Test.
ASTM F1891 Standard Specification for Arc and Flame-Resistant
Rainwear
This standard applies to flame-resistant waterproof materials used in rainwear.
Garments can be made from coated or laminated fabrics. The fabrics must
be flame-resistant as determined by ASTM D-6413 Vertical Flame test (max.
2 sec afterflame and 6 in. char length). The standard also requires the
Arc Thermal Performance Value (ATPV) to be reported, and requires a minimum
Arc Break Open Threshold (EBT) of 5 as measured by ASTM F1959 Arc Thermal
Performance Test. The standard is currently being revised to include a fabric
flammability test more suitable to coated fabrics.
NFPA 1975 Standard for Station/Work Uniforms for Fire and Emergency
Services
This standard applies to Fire Service station uniforms made from 100% cotton
and flame-resistant fabrics. Recently revised to exclude vertical flammability
testing, this standard requires that fabrics do not shrink more than 15%
after being tested in a 500°F oven for 5 minutes. This is the only thermal
requirement of this standard. Garments are subject to 3rd party testing
and inspections. In the past, NFPA 1975 was often used by industries beyond
the Fire Service to specify industrial FR garments. However, with the elimination
of vertical flammability testing, this standard is no longer adequate for
industrial FR garments.
NFPA 1977 Standard on Protective Clothing and Equipment for Wildland
Fire Fighting
This standard is used by the Forest Service and Fire Departments involved
in forest, field and other natural fires (in contrast to structural fires).
Garments that meet this standard must pass vertical flammability tests (maximum
2 sec afterflame and 4 in. char length). Fabrics must not melt, drip, separate
or ignite, nor shrink more than 10% after being tested in a 500°F oven
for 5 minutes. Fabrics must have a minimum Radiant Protective Performance
Value of 7. Garments are subject to 3rd party testing and inspections.
NFPA 2112 Standard for Flame-Resistant Garments for Protection of Industrial
Personnel Against Flash Fire
This is the first US standard that specifically addresses the need for industrial
flame-resistant uniforms. This standard requires FR fabrics to pass a comprehensive
battery of thermal tests, including
• Vertical flammability (2 sec after flame and 4 in. char length)
• Thermal Protective Performance (TPP) test (minimum TPP of 6 acl/cm2
spaced and 3 cal/cm2 in contact)
• Thermal Stability Test (fabric must not melt or drip, separate or
ignite after 5 minutes in a 500°F oven)
• Thermal Shrinkage Test (less than 10% after 5 min in a 500°F
oven)
• ASTM F1930 Thermal Mannequin Test (maximum 50% body burn after 3
sec flash fire)
This standard is not yet finalized, and therefore the thermal performance
requirements will probably change. Once published, this standard is likely
to form the basis of future laws and regulations for FR clothing in the
petroleum, chemical and other industries with a hazard of flash fire. Third
party testing and certification is being discussed as a component of this
standard.
Proposed NFPA 2113 Selection, Care, Use and Maintenance of Flame-Resistant
Garments for Protection of Industrial Personnel Against Flash Fire
This standard, also under development, will serve as a User's Guide for
industrial flame-resistant clothing. It addresses topics such as purchasing,
cleaning, repairs, storage, decontamination, retiring garments, and proper
use procedures. This standard will require that garments be certified to
NFPA 2112. |
NFPA
70E Standard for Electrical Safety Requirements for Employee Workplaces
2000 Edition
NFPA 70E addresses electrical hazard threats that are present in the workplace.
NFPA 70E requires that the employer shall document the incident energy exposure
of the worker when it has been determined that the worker will be performing
tasks within the flash protection boundary
NFPA bases incident energy exposure levels on the working distance of the
employee's face and chest areas from a prospective arc source for the specific
task to be performed. Flame Resistant Clothing and Personal Protective Equipment
shall be used by the employee, and an adequate level of protection based
upon the incident energy exposure associated with the specific task shall
be worn. |
Jobs
Covered by 70E
• Installing conductors and other electrical
equipment on industrial substations or buildings, residential or commercial
• Connecting the installations to a supply of
electricity
• Installing other outside conductors |
Jobs
Not Covered by 70E
• Installations in ships, watercraft, railway rolling stock, aircraft,
or automotive vehicles other than mobile homes and RVs
• Installations in underground mines
• Installations of railways for operation of rolling stock
• Installations of communication equip. under control of communication
utilities
• Installations under the control of electric utilities |
Category
|
NFPA
70E Requirements |
| Movement
and Visibility |
When flame resistant,
flame retardant, or treated clothing is worn to protect an employee,
it shall cover all ignitable clothing and shall allow for movement
and visibility |
| Body
Protection |
•
Employees shall wear clothing resistant to flash flame wherever there
is possible exposure to an electric arc flash.
• Such clothing can be provided as shirt and trousers, or as
coveralls, or as a combination of jacket and trousers, or, for maximum
protection, as coveralls and jacket. |
| Outer
Layers |
Garments worn
as outer layers over FR clothing, such as jackets or rainwear, shall
also be made from flame resistant material |
| Underlayers |
Meltable synthetic
fibers shall be avoided in fabric underlayers (underwear) next to
the skin. Garments worn as underlayers that neither ignite nor melt
and drip in the course of an exposure to the electric arc and related
thermal hazard may provide additional thermal protection. |
| Coverage |
Clothing shall
cover potentially exposed areas as completely as possible |
| Care
and Maintenance |
•
All personal protective equipment shall be maintained in a sanitary
and reliable condition.
• Individual protection items will normally be used in conjunction
with one another as a system to provide appropriate |
| Layering |
•
FR and natural fiber garments shall be permitted to be used for a
layered system for added protection.
• A typical layering system may include an undershirt, a shirt
and trouser and coverall.
• Specific tasks may call for specific protection systems. |
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