Chemical Engineering July 2021 - 33

Understanding NFPA standards
In response to the 2008 fatal explosion
of an Imperial sugar refinery,
OSHA created the Combustible Dust
National Emphasis directive, which
outlines policies and procedures that
create or handle combustible dusts.
Violations to the OSHA NEP result
in fines. States may provide and administer
their own programs, which,
if not identical to the federal requirements,
must be at least as effective.
No state is exempt from compliance
with the intent of the OSHA NEP.
The directive states that " NFPA
standards should be consulted to
obtain evidence of hazard recognition
and feasible abatement methods. "
Therefore, NFPA standards
are the foundation of OSHA's enforcement
tools for managing combustible
dust hazards. OSHA hasn't
created its own combustible dust
standards, which is why the NFPA
standards remain the basis for managing
combustible dust hazards.
The relevant NFPA standards are
described below.
NFPA 652. NFPA 652 provides
a framework for the minimum requirements
to be met for protecting
against dust explosions and includes
the requirement for a DHA. NFPA
654 provides prescriptive solutions
for dust explosion protection without
being specific to a particular
commodity or industry. All industries
with combustible dust hazards are
required to comply with this standard.
The reasoning leading to the
development NFPA 652 standard
came from users trying to follow the
standards for combustible dust hazards
but finding discrepancies and
conflicting, inadequate explanations.
NFPA 652 provides the minimum
requirements that must be met for
managing combustible dust hazards.
This does not eliminate the need to
meet the requirements of industry or
commodity specific standards.
NFPA 654. NFPA 654 is the Standard
for the Manufacturing, Processing
and Handling of Combustible
Particulate Solids. This standard
provides safety measures to prevent
and mitigate fires and dust explosions
in facilities that handle combustible
particulate solids. It includes
prescriptive measures to protect a
range of process equipment such as
dust collectors, conveyors and dryers.
It is not industry- or commodityspecific,
and is therefore applicable
to a range of industries and commodities
not covered by other specific
standards.
NFPA 68. NFPA 68 is the Standard
on Explosion Protection by Deflagration
Venting Standard on Explosion
Protection by Deflagration Venting.
This document focuses on explosion
venting, that is, devices and
systems that vent combustion gases
and pressures resulting from a deflagration
within an enclosure, for the
purpose of minimizing structural and
mechanical damage.
NFPA 69. NFPA 69 is the Standard
on Explosion Prevention Systems,
which covers the following methods
for prevention of deflagration explosions:
control of oxidant concentration,
control of combustible conCO2
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Chemical Engineering July 2021

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