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Dust Explosion Hazard Awareness
Guest article by David E. Kaelin Sr., Chilworth Technology Inc.
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Introduction
 There
is an old chestnut that says “Let Sleeping Dogs Lie”. This is a
mindset we can never use in the management of hazardous materials,
including combustible particulate solids (explosible dusts).
The recent report from the US
Chemical Safety and Hazard Investigation Board (CSB) states
“…combustible dust explosions are a serious hazard in American
industry, and … existing efforts inadequately address this hazard.”
The CSB study examined the record and
literature to assess the magnitude of the dust explosion hazard and
found that 281 combustible dust incidents were reported in the 25
year period ending in 2005. These incidents were responsible for 119
fatalities, 718 injuries and millions of dollars in lost facilities
and productivity.
Many serious incidents were caused by
explosions of what might be normally thought of as benign materials
such as plastics, rubber, foodstuffs and wood dust. Companies
processing and handling finely divided particulate solids need to be
aware of the potential for fire and explosion events and how
industry best practice and existing Codes and Standards can manage
the risk.
Dust Management Deficiencies
Three dust management “efforts” were
stressed by the CSB as requiring new emphasis:
- Existing codes and standards,
although comprehensive, are inconsistently applied and, as a
result ineffective
- Material Safety Data Sheets
(MSDS) are less than adequate regarding combustible powder
properties, and
- Awareness and training is needed
to ensure that operating personnel and those responsible for
safety and fire prevention oversight are knowledgeable in the
subject of dust explosion hazards and can apply existing codes
and standards to prevent dust explosions.
In addition, a common thread in many
of the most serious of the incidents was less than adequate
housekeeping practices resulting in the ignition of secondary
explosions that caused massive damage.
Codes And Standards
OSHA does not currently have a
comprehensive dust hazard standard that can be applied to general
industry, and as a result most often uses the “general duty” clause
when citing employers, usually after an event. This is a less than
effective preventive technique.
One of a half dozen important codes
for safe management of combustible dusts is the National Fire
Protection Association (NFPA), “Standard for the Prevention of Fire
and Dust Explosions, from the Manufacturing, Processing and Handling
of Combustible Particulate Solids”, NFPA 654. This and other
applicable best practices are not universally required by fire and
building codes, nor are they fully understood or applied by most
inspection authorities. i.e., just because you’ve been inspected by
an authority doesn’t mean your dust explosion hazard management is
appropriate or in keeping with current industry practice.
When conducting a preliminary hazard
evaluation of a process or operation, it should be considered best
practice in U.S. industry to review all applicable codes and
standards to ensure compliance as a minimum effort. Such an effort
can be challenging, especially if in-house technical experts are
unavailable to interpret the applicability as well as the code and
standard specifics.
MSDS - Material Safety Data Sheets
Quantitative combustible dust fire
and explosion properties are not specifically and clearly required
to be included on Material Safety Data Sheets by the existing OSHA
Hazard Communication Standard (HCS) or the American National
Standards Institute consensus standard for MSDS format and
preparation, ANSI Z400.1. As a result, when explosivity data is
included, it is often in the form of less than adequate qualitative
statements such as “Powder may form Explosive Dust/Air Mixtures”.
A similar statement could be made for
all flammable liquids, although flash point data is the most basic
data reported on MSDS to communicate the degree of ignition
sensitivity for a liquid. Why should ignition sensitivity and
explosion severity not be quantified in a similar fashion for
explosible dusts? Qualitative statements give no hint as to the
conditions required to create an explosion hazard, or the relative
violence of the resulting deflagration.
Good information on the hazardous
properties of materials is critical to the Process Hazards Analysis
(PHA) effort required by the Occupational Safety and Health
Administration’s (OSHA) Process Safety Management (PSM) standard as
well as the Environmental Protection Agency (EPA) Risk Management
Plan (RMP) rule. But, what is good information and what level of
depth is required in order to adequately understand and therefore
control the hazards associated with combustible dusts?
Many companies count on the
information in the manufacturer’s Material Safety Data Sheet, for
input to their PHA effort. Less than adequate information can be a
dangerous situation. Chilworth Technology Inc. has fully equipped
laboratories to conduct all pertinent fire and explosion,
electrostatic, and thermal instability property tests for inclusion
in risk assessment and MSDS's. Chilworth testing is conducted per
applicable national and/or international standards, and we are ISO
17025 accredited.
Training
Chilworth Technology Inc. is a
leading company in providing dust and powder hazard management
training courses, which can be tailored to your needs. We have
provided dust explosivity hazard safety training to fire marshals,
EPA inspectors, and OSHA inspectors as well as industry operating,
maintenance and design personnel. Our Process Safety Specialists are
experts in the application of best methods for the understanding and
control of fire and explosion hazards associated with powder
processing.
For more information contact:
Mr. David E. Kaelin Sr.
Senior Process Safety Specialist
Chilworth Technology, Inc.
250 Plainsboro Rd, Bldg #7
Plainsboro, NJ 08536
Tel: 609-799-4449
Fax: 609-799-5559
Email:
safety@chilworth.com
Web site:
http://www.chilworth.com/
Help others by posting your comments, suggestions and
experiences with bulk solids feeding or any other materials handling concerns you may have
on our On-Line Help Forum.
For
past Ask Joe ! Articles, visit the Ask Joe! Archived Articles.
Guest articles for the Ask Joe! Column are always welcome,
for more information please contact Joe Marinelli directly at his email address:
joe@solidshandlingtech.com.
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