Site Visits Related to Combustible Dust:

Facility T–Pharmaceutical Manufacturer

	Prepared for:

U.S. Department of Labor

	Occupational Safety and Health 

Administration

	Directorate of Standards and Guidance

	

	Prepared by:

	Eastern Research Group, Inc.

Lexington, MA 02421

(March 22, 2011)

Table of Contents

  TOC \o "1-5" \h \z \u    HYPERLINK \l "_Toc288561583"  1	Project
Overview	  PAGEREF _Toc288561583 \h  1  

  HYPERLINK \l "_Toc288561584"  2	Facility Description	  PAGEREF
_Toc288561584 \h  2  

  HYPERLINK \l "_Toc288561585"  3	Process and Activity Descriptions	 
PAGEREF _Toc288561585 \h  4  

  HYPERLINK \l "_Toc288561586"  3.1	Manual Charging of Powders to
Vessels	  PAGEREF _Toc288561586 \h  5  

  HYPERLINK \l "_Toc288561587"  3.2	Milling	  PAGEREF _Toc288561587 \h 
6  

  HYPERLINK \l "_Toc288561588"  3.3	Drying	  PAGEREF _Toc288561588 \h  6
 

  HYPERLINK \l "_Toc288561589"  3.4	Dust Accumulations	  PAGEREF
_Toc288561589 \h  6  

  HYPERLINK \l "_Toc288561590"  3.5	Equipment Cleaning and Housekeeping	
 PAGEREF _Toc288561590 \h  7  

  HYPERLINK \l "_Toc288561591"  3.6	Dust Collectors	  PAGEREF
_Toc288561591 \h  8  

  HYPERLINK \l "_Toc288561592"  3.7	Nitrogen Inerting Systems	  PAGEREF
_Toc288561592 \h  10  

  HYPERLINK \l "_Toc288561593"  3.8	Other	  PAGEREF _Toc288561593 \h  11
 

  HYPERLINK \l "_Toc288561594"  4	Document Review	  PAGEREF
_Toc288561594 \h  12  

  HYPERLINK \l "_Toc288561595"  4.1	Testing Data	  PAGEREF _Toc288561595
\h  12  

  HYPERLINK \l "_Toc288561596"  4.1.1	Facility T’s Testing Data	 
PAGEREF _Toc288561596 \h  12  

  HYPERLINK \l "_Toc288561597"  4.1.2	OSHA’s Analyses of Samples
Collected during the Site Visit	  PAGEREF _Toc288561597 \h  13  

  HYPERLINK \l "_Toc288561598"  4.2	Material Safety Data Sheets (MSDSs)	
 PAGEREF _Toc288561598 \h  14  

  HYPERLINK \l "_Toc288561599"  4.3	Process Safety Guideline on
Combustible Dust	  PAGEREF _Toc288561599 \h  16  

  HYPERLINK \l "_Toc288561600"  4.4	Process Safety Guideline on Solids
Charging	  PAGEREF _Toc288561600 \h  17  

  HYPERLINK \l "_Toc288561601"  4.5	Process Safety Guideline on Control
of Electrostatic Hazards	  PAGEREF _Toc288561601 \h  18  

  HYPERLINK \l "_Toc288561602"  4.6	Process Hazard Analyses	  PAGEREF
_Toc288561602 \h  18  

  HYPERLINK \l "_Toc288561603"  5	Training	  PAGEREF _Toc288561603 \h 
19  

  HYPERLINK \l "_Toc288561604"  6	Main Findings	  PAGEREF _Toc288561604
\h  19  

  HYPERLINK \l "_Toc288561605"  7	Feedback to OSHA	  PAGEREF
_Toc288561605 \h  22  

  HYPERLINK \l "_Toc288561606"  8	References	  PAGEREF _Toc288561606 \h 
23  

 

Table 1	 		Testing Data Provided by Facility T

Table 2			Testing Results for Samples Collected During the Site Visit

Table 3 	Comparison of Combustible Dust Hazard Information Presented on
MSDSs to Facility T Testing Data for Selected Materials

Attachment 1	Testing Results Provided by OSHA’s Analytical Laboratory

Acronyms and Abbreviations

EHS		environmental, health and safety

ERG		Eastern Research Group, Inc.

FDA		U.S. Food and Drug Administration

FM			Factory Mutual

GMP		good manufacturing practice

MIE		minimum ignition energy

mJ			millijoule

MSDS		Material Safety Data Sheet

NFPA		National Fire Protection Association

OSHA		Occupational Safety and Health Administration

PHA	
牰捯獥⁳慨慺摲愠慮祬楳൳桐䵒⁁倉慨浲捡略楴慣⁬敒
敳牡档愠摮䴠湡晵捡畴敲獲漠⁦流牥捩ൡ卐्瀉潲散獳
猠晡瑥⁹慭慮敧敭瑮

μm			micron (or micrometer) 

Project Overview 

On November 11–13, 2009, Eastern Research Group, Inc. (ERG) conducted
a three-day site visit to a pharmaceutical manufacturing facility
(hereafter referred to as “Facility T”). The site visit was
conducted by an ERG employee and a consultant. The purpose of this site
visit was to obtain facility-specific information on combustible dust
recognition, prevention, and protection programs, and to relay notable
findings and other facility feedback to the Occupational Safety and
Health Administration (OSHA). Site visit activities included touring
facility operations, reviewing relevant documentation, collecting
samples for analysis by OSHA’s analytical laboratory, and interviewing
employees who work in areas with combustible dust. 

The purpose of this report is strictly to document observations made
during the site visit, which may not reflect facility conditions at
other times. The site visit was not designed to assess Facility T’s
compliance with OSHA regulations or adherence to National Fire
Protection Association (NFPA) consensus standards and therefore, should
not be used to make such assessments. The site visit focused on safety
issues pertaining to combustible dust and was not intended to be a
facility-wide evaluation of all OSHA regulations (e.g., means of egress,
fire protection, powered platforms). This report should not be viewed as
a comprehensive review of Facility T’s operations, because site
visitors toured only a subset of the facility’s processes, and not all
of the site visitors’ observations are documented in this report. The
remainder of this report is organized into the following sections:

Organization of Report

Section	Title	Contents

2	Facility Description	General information about Facility T, such as its
main products, operational history, and number of employees.

3	Process and Activity Descriptions	Descriptions of the production
processes that ERG toured, with a focus on combustible dust safety
issues; section includes information on process-specific controls,
housekeeping practices, and equipment cleaning procedures. 

4	Document Review	Summary of various facility documents pertaining to
combustible dust safety issues.

5	Training	Review of Facility T’s training programs.

6	Main Findings	Key observations made by the site visit team. 

7	Feedback to OSHA	Feedback that Facility T representatives wished to
communicate to OSHA as it decides how to pursue combustible dust issues.

8	References	Full references for documents cited throughout the report. 

 

Facility Description

Facility T is a pharmaceutical manufacturing facility that makes
multiple drug products. The tablet products contain active
pharmaceutical ingredients and various inactive additives, known as
excipients. Facility T operates numerous batch manufacturing processes,
and site visitors toured two main production areas located in two
different buildings. 

The unit operations observed were primarily mixing, drying, blending,
and milling of active ingredients and excipients and compressing the
finished powdered products into tablets, which had images printed on
them before being packaged for distribution. Facility T’s various
production operations were constructed in different time frames. The
production lines that site visitors toured were constructed in 1992 and
2004, but some production processes at Facility T date back to 1969.

Facility T representatives indicated that the basic production equipment
and processes that were observed during the site visit are expected to
be fairly standard in the pharmaceutical manufacturing industry. Thus,
the potential combustible dust hazards observed during the site visit
are likely reasonably representative of those experienced by other
companies that manufacture similar pharmaceutical products.

Approximately 2,200 full-time employees work at Facility T. Two facility
employees who work full-time on safety issues participated in the site
visit, as did the facility’s Environmental, Health and Safety Manager.
The two safety personnel are responsible for a wide range of safety
programs, which include complying with process safety management (PSM)
requirements and identifying and addressing potential combustible dust
safety hazards. 

In addition, the company that owns Facility T has approximately 25
employees working across the corporation in its corporate process safety
practice. This includes employees at other manufacturing plants and at
the corporate level. These employees are responsible for developing
guidance and advising facilities on a wide range of environmental,
health and safety (EHS) topics, including combustible dust safety
hazards. Facility T receives input both from the corporate
environmental, health and safety practice and designated regional EHS
personnel. 

Facility T has its own fire brigade with approximately 75 volunteers.
The fire brigade responds to incidents at Facility T, and also has a
history of supporting local and regional fire fighting efforts that
occurred in the community. Facility T representatives reported that they
had no history of major fires and explosions due to combustible dusts.
Smoking is not allowed at Facility T; site visitors noticed no evidence
of smoking (e.g., discarded cigarettes) in or near the main production
areas.

ERG asked the facility’s safety personnel to comment on the roles that
outside parties play in Facility T’s combustible dust safety programs.
A summary of those responses follows: 

The local fire marshal requires Facility T to have a license to operate
and inspects Facility T annually. However, these inspections typically
focus on safe chemical storage, sprinkler systems, and other
conventional fire protection issues, and do not specifically address
combustible dust. The fire marshal does not require compliance with NFPA
combustible dust standards. 

Facility T’s insurance underwriter, Factory Mutual (FM), is actively
engaged in facility safety issues. FM representatives spend up to 8
weeks per year working on site to evaluate the facility’s various
safety and accident prevention measures. FM representatives advise
Facility T on a wide range of topics, including PSM, combustible dusts,
and natural disasters (e.g., hurricanes). Facility T representatives
noted that FM has previously provided useful information on mitigating
potential combustible dust safety hazards and that FM will be conducting
a facility-wide assessment of potential combustible dust safety hazards
during a future site visit. 

The company that owns Facility T has a large process safety practice
that is very actively engaged in researching combustible dust safety
issues, preparing company-wide policies and procedures, and implementing
hazard mitigation strategies. The corporate process safety group is
Facility T’s primary source of trusted information on combustible
dust. This company also has its own testing laboratory that conducts
explosibility and combustibility testing for samples provided by
multiple manufacturing facilities, including Facility T. 

Facility T representatives and corporate safety officials noted that
they also seek information on combustible dust from various
publications, including the Chemical Safety and Hazard Investigation
Board’s incident reports, documents issued by the Center for Chemical
Process Safety, and papers in the peer-reviewed literature. 

Facility T has hired external consultants on various issues pertaining
to combustible dust, but mostly for testing of samples (for parameters
that are not typically evaluated in the corporate testing laboratory)
and training the facility’s safety professionals. 

Facility T conducts annual site assessments of regulatory compliance
using a third-party commercial software product. The software guides
designated evaluators through applicable government safety and
environmental regulations, as well as selected corporate guidelines. 

Facility T has not consulted directly with OSHA on combustible dust
safety issues. However, facility representatives and corporate process
safety officials were generally aware of the agency’s ongoing
activities pertaining to combustible dust. For example, they had visited
OSHA’s combustible dust website, downloaded and read the Combustible
Dust National Emphasis Program, and were aware of the agency’s
Advanced Notice of Proposed Rulemaking. OSHA officials have not visited
Facility T as part of the National Emphasis Program.

The company that owns Facility T is a member of the Pharmaceutical
Research and Manufacturers of America (PhRMA) trade association.
Facility T representatives indicated that they have accessed information
on combustible dust safety issues from PhRMA, but the trade association
is not the facility’s primary source of information on combustible
dust. 

Facility T is typically inspected annually by the U.S. Food and Drug
Administration (FDA). While these inspections do not focus on
combustible dust safety hazards, they do evaluate whether the facility
uses “Current Good Manufacturing Processes” to ensure product
quality and avoid cross-contamination in products. As described later in
this report, Facility T must ensure that all production equipment is
thoroughly cleaned before switching production campaigns, and tests must
be run to validate equipment cleanliness. Therefore, even though FDA
regulations were not promulgated to protect employees from combustible
dust safety hazards, their emphasis on product purity has the secondary
benefit of minimizing combustible dust accumulations. 

Process and Activity Descriptions

This section describes the process operations and production activities
that the site visitors viewed at Facility T. The exact sequence of unit
operations in a given process depends on the drug product being
manufactured, but processes typically involved mixing together active
ingredients with various excipients and compressing the resultant
mixtures into tablet products. Some active ingredients are synthesized
onsite in reactors, and others are purchased as raw materials. Specific
unit operations used to formulate the pharmaceutical products include
reactors, granulators, dryers, sifters, mills, and blenders. After the
final material is formulated, different finishing operations occurred
(e.g., compressing powder into tablet form, coating, and printing). 

Site visitors examined several operations and activities relevant to
combustible dust hazards, but generally focused on areas that processed
dry materials (i.e., moisture content less than 2 percent). The
remainder of this section summarizes the site visitors’ observations
of selected combustible dust safety issues. These specific issues were
selected for more detailed summaries either (1) because they demonstrate
unique challenges faced by this facility or industry, (2) because they
highlight effective engineering or administrative solutions implemented
by Facility T, or (3) because they pertain to specific safety issues
OSHA might be considering in its rule-making effort. 

Manual Charging of Powders to Vessels

Many of the active ingredients and excipients used by Facility T arrive
at the facility in dry, powdered form, and packaged in fiber-board drums
with plastic liners. These plastic-lined drums are also used to transfer
dry materials from one production area to the next. Employees at
Facility T manually poured the solid powders from drums into various
larger vessels (e.g., reactors and mixers), sometimes using funnels and
chutes to minimize spillage. The drums were also used when removing
material from process vessels. 

Facility T representatives recognized that manual charging of solids
could generate potentially explosive dust concentrations within vessels,
and near their openings. Employees typically use drum-lifting and
tipping devices during these material transfer operations, thus reducing
the likelihood of large spills and minimizing the risk of back strain
and repetitive motion injuries. For the largest reactor vessels,
employees charged approximately 60 drums of powder material into the
reactors over a short time frame, with each drum containing roughly 50
kilograms of dry ingredients.

Hazards are minimized by following the facility’s written procedures
for charging solids into vessels. These procedures outline many
requirements, such as ensuring that solids that can form combustible
dusts are charged to vessels only after interior oxygen concentrations
have been reduced safely below the limiting oxidant concentration (see
Section 3.7) and performing this operation during a continuous purge of
inert gas. Refer to Section 4.4 for further information on the written
procedures for charging vessels with solids. 

All indications were that Facility T employed extensive measures to
ensure that equipment and drums were properly grounded and bonded.
However, employees who performed material transfer operations did not
wear grounding straps and most did not wear conductive shoes (or shoe
covers). Site visitors encouraged Facility T representatives to consider
the need for such controls for employees whose job duties might cause
them to work in or near dust clouds (e.g., those who remove lids of
drums containing powder, those who manually scoop solids from drums into
vessels). Facility T representatives indicated that they have been
considering the possibility of installing “de-energizing stations”
where employees can periodically dissipate any static charges that they
have accumulated. 

Milling

All milling operations at Facility T occur in rooms equipped with
explosion panels for deflagration venting. These rooms were designated
as Class II, Division 2 locations, and the electrical fixtures in these
rooms were reportedly rated for this classification. All milling
equipment is grounded and bonded to dissipate electrostatic charges.
Most milling operations occurred in nitrogen atmospheres, and all have
fine airborne dusts exhausted to dust collectors. 

A potential ignition source identified by site visitors is tramp metal
entering the mills. While the probability of tramp metal being found in
active ingredients and other raw materials appears to be low, a more
likely scenario for tramp metal entering the process is from metal parts
within process equipment (e.g., bolts, wires from sifting screens)
becoming loose and acting as a potential ignition source. Use of
magnetic separators at locations upstream of milling devices can help
reduce the risks of tramp metal acting as an ignition source in these
operations.

Drying

Facility T operated dryers to reduce the moisture content in
intermediate mixtures, and site visitors toured one production area
equipped with a fluidized bed dryer. The dryer was in a designated Class
II, Division 2 location, and was equipped with multiple interlocks that
prevented it from operating unless several key conditions were met: the
filter gasket had to be grounded, the filter ring had to be grounded, a
safety clamp had to be engaged, and others. Further, a mechanical quick
acting valve was placed on the connection between the dryer and other
unit operations to help prevent fires from propagating through these
interconnected vessels. 

A continuous temperature sensor was placed in the dryer exhaust stream
to detect potentially unsafe operating conditions, and this sensor
triggers nitrogen inerting if elevated temperatures indicate the
potential for a fire in the dryer. Site visitors noted that more rapid
control of unsafe operating conditions could involve continuous
monitoring of temperatures within the dryer (as opposed to in its
exhaust) and triggering alarms or purges as measured values approach and
exceed auto-ignition temperatures or other thresholds. 

Dust Accumulations 

Site visitors observed virtually no dust accumulations in nearly every
production area toured. Of particular note, no visible dust
accumulations were observed in the immediate proximity of the reactors
where large quantities of powders were manually charged to vessels. The
lack of dust accumulations likely resulted, in large part, from FDA
regulations that require use of “Current Good Manufacturing
Processes” at pharmaceutical manufacturing facilities. Site visitors
noted minimal dust accumulations in just two locations at Facility T: 

One dust collector was equipped with an exhaust vent that directed clean
air outdoors to the ambient environment. However, the exhaust ductwork
did not actually extend outdoors, but rather ended just shy of the
building exterior, allowing for dusts in the exhaust to potentially
settle indoors. Site visitors noted a small amount of fine dust
accumulation on a ledge located beneath the terminus of this duct
collector’s exhaust ducting—a solution that could be easily fixed by
extending the ductwork to reach the outdoors or by sealing the visible
gap between the ductwork terminus and the building exterior.  

In one area where milling and sifting occurred, site visitors noted
minimal accumulation of powdery dust on parts of the floor. This minimal
accumulation apparently resulted from an operation that had just
occurred, but had not yet been followed up with scheduled cleaning. 

Site visitors’ observations of minimal dust accumulations reflect
conditions only on the day of the site visit and at the specific
locations toured. However, input received during employee interviews
suggested that Facility T’s standard practice is to remove any dust
accumulations as soon as they are generated. 

Equipment Cleaning and Housekeeping

Facility T routinely cleaned all vessels that contact materials that can
eventually be part of pharmaceutical products. Though facility personnel
appeared aware of combustible dust safety hazards, the rigorous
equipment cleaning protocols seemed to be motivated primarily by FDA
regulation and the critical need to avoid cross-contamination of
products. 

Site visitors reviewed cleaning procedures for one of Facility T’s
milling rooms. These procedures call for routine cleaning between
product changeovers and following any maintenance work. During these
cleaning events, employees thoroughly rinse the interior of the milling
units with purified water, and then further rinse and hand-wipe the
equipment with ethanol. After the equipment is cleaned, employees
conduct swab tests (per FDA requirements) of mill interior surfaces to
assess whether material from previous production campaigns remained in
the equipment. Taken together, these cleaning steps achieve their
primary goal of avoiding cross-contamination of products, but also help
ensure that unsafe levels of combustible dust do not accumulate in most
equipment. 

In addition to the cleaning campaigns noted above, employees also
conducted biweekly cleaning of milling rooms. While the cleaning between
production campaigns focused on dust accumulations within and near
equipment, the biweekly cleaning addressed the entire rooms in which
mills were located. Facility employees used compressed air to dislodge
dusts that adhered to or accumulated upon elevated surfaces and blew
this material to the floor, where settled material was then washed to
drains. 

Site visitors collected information on Facility T’s equipment cleaning
procedures for selected other unit operations. The cleaning procedures
for other vessels were generally consistent and involved some
combination of water and ethanol. 

Dust Collectors 

The production areas toured during the site visit had 21 dry dust
collectors, all of which collected dusts in cartridges or bags. No wet
dust collectors were used in these operations, reportedly out of concern
of added wastewater treatment costs associated with such technologies. 

The dust collectors controlled dusts generated by dryers, milling
operations, sifters, blenders, and various other production processes.
Some dust collectors controlled dusts generated by a single unit
operation, while others controlled dusts from multiple operations. In
the latter case, the inlet air streams from the different processes were
connected via manifolded ductwork that led to a single duct at the dust
collector inlet. Except for the example noted in Section 3.4, site
visitors did not observe dust accumulations near dust collectors. 

Collected dust was periodically removed, typically into conductive
plastic bags placed in drums. (Note: The dissipative properties of
plastic liners used at Facility T are discussed further in later
sections of this report. The bags used for removing material from dust
collectors did not have to meet site good manufacturing practice [GMP]
requirements, because this material is considered waste and was not used
to make pharmaceutical products.) Facility T maintenance personnel
routinely checked dust collectors for dust accumulations, with collected
material removed weekly or monthly. 

All 21 dust collectors were located indoors. In one manufacturing area,
dust collectors were on the top floor of the production building—one
floor above the main production areas where most operators worked and
where dusts were generated. In another manufacturing area, the dust
collectors were located on the same floor as production equipment, but
segregated from the primary unit operations. As the exception, one dust
collector was fixed to the walls and ceiling in the same room as
multiple unit operations.

The dust collectors varied in terms of exhaust venting characteristics.
Some dust collectors vented exhaust air directly outdoors to the ambient
environment. Others returned exhaust air back into the workplace, but
only after the cleaned air passed through three sequential particulate
filtration steps. Most ducts that returned air to workplaces were
equipped with smoke detectors that would activate abort gates in the
event of fire. These ducts were not equipped with explosion isolation
devices, however. Consequently, deflagrations initiating in the dust
collectors had the potential to propagate through inlet and exhaust
ductwork into workplaces—and potentially into several different
workplaces for those dust collectors that control multiple operations
through manifolded ductwork. 

Nearly every dust collector that site visitors observed was equipped
with explosion panels. Facility T representatives reported that the size
and release specifications for these panels were based on measured
properties (i.e., the deflagration index) for the most sensitive
materials processed. Employees interviewed during the site visit were
unaware of the dust collector explosion panels ever blowing out. For
several dust collectors, the explosion panels were designed to vent
deflagrations through a relatively short segment of ductwork to the
building exterior. On the other hand, some older dust collectors had
explosion panels that would vent deflagrations indoors. For instance,
one set of explosion panels was located on the top of a dust
collector—a design that would vent deflagrations upwards directly
toward additional ductwork and the facility rooftop. In this case, an
improved design for the dust collector (if it could not be readily moved
to another location) would be explosion panels that vent deflagrations
through ductwork to the outdoor environment. Alternatively, the
explosion panels could be replaced with flame arrestors or other control
technologies that would not vent uncontrolled deflagrations directly
into indoor environments. 

Most dust collectors viewed during the site visit were equipped with
smoke detectors placed in the interconnecting ductwork. The number and
placement of smoke detectors varied across the dust collectors. Detected
alarm conditions would trigger different actions in different dust
collectors. In some cases, alarm conditions would activate abort gates
in the exhaust ductwork and shutdown airflow through the dust collection
system, but would not trigger fire suppression. For the more recent
installations, smoke detectors were interlocked directly with sprinklers
inside the dust collectors. Site visitors encouraged Facility T
representatives to consider having smoke detection trigger as many
controls as possible (e.g., activation of abort gates on exhaust ducts,
dampers on inlet ducts, and fire suppression in the dust collector). 

Nitrogen Inerting Systems

Facility T used nitrogen inerting to reduce oxidant concentration inside
several unit operations, thus removing a required element for
deflagrations. This section focuses on the use of nitrogen inerting in
the facility’s reactors—the largest vessels in which inerting was
conducted. Inerting was adopted because manual solid charging was
believed to lead to potentially explosive dust concentrations inside the
vessels. Further, the reactor interior surface is glass-coated, thus
offering no protection against buildup of static electricity. Operators
of the individual reactors follow Facility T’s written operating
procedures for charging the vessels, and some key observations regarding
the nitrogen inerting are presented here.

Facility T representatives reported that the oxygen concentrations in
the reactor have to be below 2 percent before solids charging can occur;
and while material is being loaded to the reactors, operating procedures
require oxygen concentrations to be below 5 percent. Based on the
limiting oxidant concentration of the powder material reported by the
facility (7.9 percent), the maximum allowable oxygen level meets
requirements set forth in Section 7.7.2.5 of NFPA 69. 

The reactor vessels are equipped with automated continuous oxygen
monitoring systems that are interlocked with alarms. When oxygen
concentrations exceed 5 percent during solids charging, an audible alarm
sounds in the control room and at the material loading station.
Employees are instructed to stop loading solids into the reactors until
increased nitrogen purge rates reduce oxygen concentrations to their
desired range (i.e., less than 5 percent). 

Recognizing the importance of the automated continuous oxygen monitoring
system, site visitors asked Facility T representatives about contingency
measures to ensure the systems function properly. Facility T
representatives noted that the monitoring systems are operated according
to manufacturer specifications, with regular span checks at oxygen
concentrations of 0, 50, and 100 percent and instrument calibrations.
Further, intermittent nitrogen purges of the sampling lines help avoid
clogging, which could otherwise generate invalid oxygen measurements.
Finally, operators have options for manually testing oxygen levels in
the reactors as an added safeguard against potentially malfunctioning
continuous systems. Despite these measures to ensure proper oxygen
measurement, site visitors encouraged Facility T to conduct a more
formal evaluation of the robustness of its continuous oxygen monitoring
systems, consistent with specifications in Section 7.1.2.1 of the 2006
edition of NFPA 654. 

To ensure that workers did not encounter oxygen-deficient atmospheres
when working near nitrogen purging systems, rooms containing equipment
that operate under nitrogen purges have oxygen sensors that monitor the
workplace air. Should the nitrogen purge unexpectedly begin to displace
ambient oxygen to dangerously low levels, a “low oxygen alarm” will
sound and alert employees of the potential hazard. 

Other

The remainder of this section documents various additional observations,
production operations, and dust control measures not summarized in the
earlier discussion: 

Classification of Hazardous Locations. Nearly every production room that
site visitors toured was designated a Class II, Division 2 location.
This included rooms with sifters, milling operations, dryers, and
blenders. Areas that handled both powder material and flammable solvents
were classified as Class I, Division 1 areas. In all cases observed, the
electrical classification of a given room was posted. 

Fire History. Facility T representatives shared accounts of fires and
explosions that have occurred in other pharmaceutical manufacturing
facilities, but reported that they had no history of major fires or
explosions associated with combustible dusts. When asked about the
potential for incidents, facility representatives noted that some
plastic linings used in storage drums have previously shown evidence of
charring, but no fires have occurred. 

Electrostatic Controls. As noted previously, all production equipment
and storage drums that site visitors observed at Facility T were either
grounded or bonded. Site visitors also inquired about the level of
electrostatic control offered by the plastic liners used to hold powder
material in the fiber-board drums and plastic drums. Facility T
representatives noted that identifying an adequately protective plastic
lining has been challenging due to the very limited number of options
that meet site GMPs. (Note: Consistency with GMPs is required because
the linings come into direct contact with ingredients used to formulate
pharmaceutical products.) To illustrate this concern, Facility T
personnel indicated that they had previously considered using
dissipative plastic lining bags made from carbon impregnated polymers,
but did not pursue this after finding evidence of carbon leaching into
the bags’ contents. 

Building Explosion Panels. Most production rooms that site visitors
toured were equipped with building explosion panels. The newest panels
installed are designed to release when interior pressures exceed 65
pounds per square foot, or approximately 0.5 pounds per square inch.
Because Facility T is in a hurricane-prone region, the explosion panels
not only had to be designed to blow out when elevated pressures occurred
within the building, they also had to withstand high exterior pressures
and projectile impacts that could occur during tropical storms and
hurricanes. Site visitors encouraged Facility T personnel to consult
with their insurance underwriter or the panel manufacturer to confirm
that panels were installed using the appropriate washers, bolts, and
other components.

Facility T provided information on the costs for purchasing and
installing explosion panels. The most recent project involved adding
panels to two production rooms. Overall, 13 panels were purchased and
installed, with individual panels ranging in size from roughly 3 x 4
feet to 11 x 11 feet. Total project costs were approximately $77,000—a
cost that included purchase, shipping, installation, and taxes, but did
not include engineering design. The costs for the engineering analysis
(e.g., drawings, panel selection, panel sizing) were not available
during the site visit. 

Document Review

This section summarizes documents pertaining to combustible dust safety
issues that Facility T made available to site visitors. This section
does not review every document that site visitors evaluated, but focuses
on documents that offered unique insights into combustible dust safety
issues and Facility T’s approaches for controlling them. 

Testing Data

Testing data for materials that Facility T handles and produces were
available from two sources: Facility T made selected testing results
available to site visitors for review, and the site visitors collected
three samples, which were sent to OSHA’s laboratory for testing. This
section summarizes both data sets. 

Facility T’s Testing Data

Facility T is owned by a company that operates its own testing
laboratory, which is equipped to test dust samples for a wide range of
combustibility and explosibility parameters. The laboratory can apply
multiple testing methods published by the American Society for Testing
and Materials (ASTM). The corporate laboratory tests samples of most
active ingredients that Facility T processes, while testing data on
excipients is typically obtained from suppliers, peer-reviewed
literature, and other sources. In some cases, excipients are sent to a
commercial laboratory for testing. 

The testing costs for the corporate laboratory vary by the parameters
measured, and estimated costs for individual tests follow:

	Minimum ignition temperature of a dust cloud (ASTM E-14912)			$1,150

	Minimum explosible concentration (ASTM E1515)						$1,495

	Explosion severity test (ASTM E1266)									$2,095

	Minimum ignition energy of a dust cloud (ASTM E2019)				$1,150

Facility T representatives noted that the overall expense of testing
samples can be considerably greater than the laboratory costs, depending
on the material tested. Specifically, for selected active ingredients
and pharmaceutical products, the value of the material collected in a
1-liter sample can be comparable or greater than the laboratory costs
listed above. 

The company that owns Facility T has conducted combustibility and
explosibility testing for a broad array of active ingredients and
excipients, and testing results are logged into a central database that
representatives from individual facilities can access. In order for the
past testing results to be interpreted in proper context, site visitors
encouraged Facility T representatives to include database fields on
particle size distribution, moisture content, and collection locations. 

Facility T representatives shared testing data for three active
ingredients and three excipients. Table 1 summarizes these parameters. 

OSHA’s Analyses of Samples Collected during the Site Visit

During the site visit, Facility T representatives collected three
samples to be tested by OSHA’s laboratory. Because ERG site visitors
were not present when the samples were collected, limited information is
available on the exact materials and locations sampled. Table 2
summarizes the testing results, and Attachment 1 presents the original
laboratory testing documentation. More information on the samples
collected and the test results follows:

Sample #2673: Material 1. Facility T personnel identified this sample as
“pharmaceutical #2,” which was collected from “blender #3.” The
physical state of the sample was a dry (1.8 percent moisture), white
powder. The testing concluded that this material is a Class II dust.

Sample #2674: Material 2. Facility T personnel identified this sample as
“pharmaceutical #1,” which was collected from “blender #1.” Like
the previous material, this sample was a dry (1.0 percent moisture),
white powder that was found to be a Class II dust. 

Sample #2675: Material 3. Facility T personnel identified this sample as
“pharmaceutical #3,” but did not specify the process location where
the sample was collected. The sample was a dry (2.0 percent moisture)
powder. Though a Class II test was requested, the laboratory could not
perform this test because the material was too coarse. The laboratory
instead tested the sample for explosibility, and concluded that the
material tested was explosive (Kst = 12.5 bar-meter/second).

As noted in the testing results (see Attachment 1), the data presented
above should not be used in designing or engineering protective safety
equipment for various reasons.

Material Safety Data Sheets (MSDSs) 

Facility T provided copies of 11 material safety data sheets (MSDSs) for
selected active ingredients, excipients, and solvents. Site visitors
reviewed the subset of MSDSs that pertained to materials that were, or
could generate, combustible dusts. The extent of documentation of
potential combustible dust safety hazards varied greatly across the
MSDSs that ERG reviewed, with information on these hazards typically
documented in sections on firefighting measures, accidental release
measures, handling and storage, and stability and reactivity. Following
are four main observations about the MSDSs that site visitors reviewed:

Quantitative information on combustibility and explosibility. Most MSDSs
provided to site visitors included no quantitative information on the
materials’ combustibility and explosibility. Following are excerpts
from the two MSDSs that included quantitative data. An MSDS for an
active ingredient reported the following parameters: 

			“Max. rate of pressure rise (bar/s):		652

			Kst value (bar-m/s):						176

			Min. Ignition Energy – Cloud (mJ):		50

			Min. Ignit. Temp. Dust Cloud (oC):		430

			Min. Explosive Conc. (g/m3): 			35”

In addition, an MSDS for an excipient included the following
quantitative (and semi-quantitative) information:

			“Explosive properties: [Excipient]: ST-1.

			Minimum ignition temperature: [Excipient]: 420 deg. C.”

For all other materials, the MSDSs either provided strictly qualitative
information on combustible dust safety hazards or offered no such
information at all. 

Qualitative information on potential combustible dust hazards. A greater
proportion of the MSDSs that site visitors reviewed provided qualitative
information on potential combustible dust hazards. However, the level of
detail varied considerably across these MSDSs. As an example of a more
detailed account, an MSDS for an excipient reports: 

“CAUTION! May form explosive dust-air mixture.” “Unusual fire and
explosion hazards: Do not permit dust to accumulate. When suspended in
air, dust can pose an explosion hazard. Minimize ignition sources. If
dust layers are exposed to elevated temperatures, spontaneous combustion
may occur. Pneumatic conveying and other mechanical handling operations
can generate combustible dust. To reduce the potential for dust
explosions, electrically bond and ground equipment and do not permit
dust to accumulate. Dust can be ignited by static discharge.”

Other MSDSs for excipients provided similar, but less detailed,
insights. Examples include: “Accumulation of overhead settled dust may
form explosive concentrations in air when disturbed and
dispersed…According to NFPA 68 (explosion venting guide), the hazard
class of dust deflagrations for [excipients] is ST-1, the lowest hazard
class.” And: “This material in sufficient quantity and reduced
particle size is capable of creating a dust explosion…Use with
adequate ventilation. Minimize dust generation and accumulation.”

Similarly, the MSDSs for active ingredients varied in terms of
information conveyed on combustible dust hazards. One MSDS, for
instance, reports: “Based on accepted industry tests, the powder is
classified as a moderate explosion hazard… Prevent the generation of
airborne dusts.” On the other hand, another MSDS is less definitive
about the material’s combustibility, indicating: “This material is
assumed to be combustible. As with all dry powders, it is advisable to
ground mechanical equipment in contact with dry material to dissipate
buildup of static electricity.” 

Comparison of testing data to MSDS content for selected materials. For
three materials, the facility separately provided (1) MSDSs and (2)
testing data generated by the corporate testing laboratory. As the
comparison in Table 3 shows, information presented on the MSDSs was not
always consistent with indications from the testing data. For example,
according to Table 3, Facility T’s testing data indicate that a
particular active ingredient is combustible and relatively sensitive to
ignition; however, the language the supplier uses on the MSDS is
somewhat generic (“…as with all dry powders…”) and provides
limited insight into the material’s specific hazards. Further, for an
excipient listed in Table 3, the supplier’s MSDS reports a dust
explosion class (St1) that conflicts with results from Facility T’s
testing data (St2). 

MSDSs from Foreign Suppliers. Facility T representatives noted that they
have encountered some difficulty obtaining material-specific hazard
information from foreign suppliers, who might not be subject to minimum
disclosure and reporting requirements set forth in OSHA’s Hazard
Communication Standard. In cases where suppliers translate hazard
information into English, Facility T representatives voiced concern
about the quality of translations in some instances, particularly with
regards to highly technical detail. (Note: Site visitors did not review
any MSDSs provided by foreign suppliers.)  

Process Safety Guideline on Combustible Dust

The company that owns Facility T has prepared technical guidelines to
inform employees at its facilities about hazards associated with
handling combustible dusts. These written guidelines (18 pages) were
developed to help facilities recognize the potential for combustible
dust explosions and to identify measures to mitigate these hazards. Site
visitors briefly viewed these guidelines during the site visit, and a
brief summary of key points follows. 

The guidelines define a “dust explosion potential” to occur whenever
1 or more pounds of combustible dust per 1,000 cubic feet of volume is
typically found in suspension, or could be found in suspension, inside
enclosures or pieces of process equipment. Modifying criteria are used
in this definition when dusts are used with flammable solvents and when
dusts are involved in certain high energy operations (e.g., milling,
drying). 

Facility T’s written combustible dust safety guidelines present a
series of technical evaluations that should be conducted for any process
with a dust explosion potential. These evaluations begin with a
preliminary hazard assessment, in which material-specific combustibility
and explosibility parameters are collected and evaluated. The guidelines
recommend testing for all active pharmaceutical ingredients, and explain
how particle size and moisture content should factor into the testing
strategy. Further, the guidelines include information on which specific
parameters should be measured, depending on the type of material and the
processes in which it is used. Where new testing is not required, the
guidelines list several references with compilations of combustibility
and explosibility parameters for dusts commonly encountered in this
industry (e.g., Eckhoff, 2003; NFPA 68 and the NFPA Fire Protection
Handbook; Bartknecht, 1990; Babrauskas, 2003). 

The facility’s combustible dust guidelines use a flow chart to
recommend specific hazard mitigation strategies based on material
properties and production operations. Facilities answer questions in the
flow chart to assess whether equipment explosion protection is required,
whether fire protection options are necessary, and other design
considerations. For example, recommended electrostatic control measures
depend on the measured minimum ignition energy (MIE), with limited
controls suggested for materials with MIE greater than 100 millijoules
(mJ) to extensive controls for materials with MIE less than 1 mJ.
Similarly, the need for explosion protection is based, in part, on four
material properties: MIE, minimum ignition temperature of a dust cloud,
deflagration index (Kst value), and thermal instability temperature. The
guidelines present a matrix that use these parameters to assign a
“low,” “medium,” or “high” explosion rank
risk—designations that determine whether explosion protection is
required. 

Process Safety Guideline on Solids Charging

The company that owns Facility T has prepared technical guidelines on
“Solids Charging.” These written guidelines (16 pages) document
process safety considerations for the equipment and containers involved
when employees charge solids to vessels. The guidelines cite multiple
references, including NFPA standards 68, 69, 70, 77, and 654 and
“Guidelines for Safe Handling of Powders and Bulk Solids” by the
Center for Chemical Process Safety. 

The solids charging guidelines, which were made available to the site
visitors, included extensive information on potential safety hazards
associated with charging vessels and specific measures that should be
taken to prevent accidents (e.g., fires, explosions, uncontrolled
emissions). The guidelines recommended that facilities conduct a formal
review of hazards associated with charging powders under three
circumstances: (1) when powders have minimum ignition energies less than
10 mJ; (2) when charging solids in the form of solvent-laden cake; or
(3) when charging powders into a vessel containing flammable solvents. 

When any of the aforementioned conditions are met, the guidelines
identify a series of controls to consider for the solids charging
operations. For instance, the guidelines recommend that solids should
only be charged to non-flammable atmospheres in vessels, where oxygen
levels are maintained safely below limiting oxidant concentrations.
Continuous purging with an inert gas is also advised. The guidelines
further recommend several other hazard control measures (e.g., solids
should be charged using a flapper valve to provide a “semi-closed”
system, all equipment must be grounded, and static dissipative plastic
liners must be used in drums). The guidelines also identify employee
practices that should be followed and specific practices to avoid, such
as shaking bags to remove residual powder and any loading activity that
generates dust clouds. Employees interviewed during the site visit
exhibited awareness of the specific safe work practices outlined in
these written guidelines. However, employees involved in certain solids
charging activity reported striking funnel walls with large mallets to
dislodge solids that adhere to funnel walls—a practice that did not
appear to be consistent with the solids charging guidelines. 

Process Safety Guideline on Control of Electrostatic Hazards 

In 1998, the company that owns Facility T developed an internal guidance
document that communicated basic principles of static electricity and
electrostatic hazards and that recommended various measures to control
these hazards in production operations. The guidance presents basic
scientific principles on electrostatics (e.g., formation and dissipation
of charges) and the relationship between material properties (e.g., MIE)
and hazard potential. The guidelines also document safe operating
procedures for selected activities: filling, emptying, and opening
containers with powders; charging powders into flammable atmospheres;
maximum fill rates for solids charging; compatibility of plastic liners
with different types of mixtures; grounding and bonding of equipment and
drums; and various other common operations. All Facility T employees who
work with combustible dust safety hazards receive training on the
concepts outlined in these guidelines. 

Process Hazard Analyses

Facility T representatives indicated that they had completed 55
different process hazard analyses (PHAs). Many were completed in
fulfillment of requirements under OSHA’s PSM standard, but the
facility also has a policy of conducting PHAs for certain potentially
hazardous operations that are not subject to this regulation. 

Site visitors reviewed one of Facility T’s PHAs, which was compiled in
a 2-inch binder and reflected contributions from a dozen employees,
including engineers, operators, maintenance personnel, and process
safety specialists. This PHA pertained to reactors used to synthesize an
antibiotic from a precursor. The binder included a wide range of
background information, including (but not limited to) a process flow
diagram, a description of process chemistry, a process and
instrumentation diagram, mechanical integrity documentation, checklists
for human factors and facility siting, and MSDSs for raw materials,
intermediates, and products. 

The PHA identified and evaluated a series of potential safety and health
hazards. For each condition identified, information was documented on
potential causes, consequences, and safeguards for the hazards.
Additionally, the PHA made recommendations for avoiding the hazards and
assigned responsibilities to individuals to implement the
recommendations. Each hazard was also evaluated in a 4 by 4 matrix that
considered both the hazard’s likelihood (improbable, remote, likely,
and frequent) and severity (negligible, marginal, critical, and
catastrophic). 

Training 

Facility T offers dozens of training courses to its employees and
contractors, with job duties determining which subset of training
courses they must take and how often. The facility uses a computerized
system to manage their training programs. The software not only tracks
training requirements and reminds employees and managers when training
is overdue, but it also contains many online versions of training
courses. Employees routinely access the system to ensure their training
is up-to-date and use the software either to take online courses or
enroll for courses that are not computerized. Most training courses were
offered in both English and Spanish. 

Site visitors did not view any of the training courses, but noted some
examples of the many courses that Facility T offers. Training topics
included, but were not limited to, the following:

Procedures for charging solids to reactors

Procedures for charging solvents to reactors

General handling procedures for combustible dust

Training certification for PSM processes

Static electricity hazards and controls

Milling equipment cleaning procedure

Product handling between plants

Quarterly equipment cleaning procedures

Electrical safety training	HAZWOPER training

Hot work procedures

Confined space entry procedures

Emergency preparedness training

Hazard communication training

New hire orientation

Personal protective equipment training

Respiratory protection training

Reporting work-related injuries, illnesses, and near misses



Main Findings

During the closing meeting of the site visit, the ERG site visitors
shared several key findings. These represent observations raised by two
independent engineers and should not be viewed as a judgment on Facility
T’s compliance with OSHA regulations or adherence to NFPA consensus
standards. The main findings communicated to Facility T representatives
include: 

Facility T’s safety staff exhibited a high level of awareness of
combustible dust safety issues, and the added support provided by the
corporate process safety practice enhanced this awareness. Both facility
and corporate safety personnel appeared to be very knowledgeable of
existing NFPA standards and pending revisions, and they worked
cooperatively to address potential combustible dust safety hazards. As
testament to this, the company that owns Facility T took the proactive
step of preparing and implementing Process Safety Technical Guidance on
multiple topics pertaining to combustible dust safety issues. 

In most production areas, no dust accumulations were visible. In some
isolated areas, such as near milling operations and beneath the exhaust
duct of a dust collector, minimal accumulations were observed. The clean
workplace likely resulted from multiple factors: applicability of FDA
cleaning requirements; attention to facility and corporate housekeeping
policies; and the economic value of the drug product being processed
(i.e., loss of active ingredients and pharmaceutical products at
Facility T is far more costly than loss of comparable quantities of wood
dust, sugar dust, or other such commodities at other facilities). Some
production rooms had drop ceilings, and site visitors could not assess
whether combustible dusts were accumulating above these ceilings or in
other hidden areas. 

Facility T had extremely extensive testing data available, both in terms
of the number of materials that have been tested and the number of
parameters that have been measured. Internal documentation of testing
results can be enhanced by (1) ensuring that particle size distribution
data are logged alongside the material-specific explosibility and
combustibility parameters and (2) more precisely documenting the
locations from where samples were collected. Given that corporate
process safety guidelines for combustible dust have specific controls
required for materials having MIE less than 4 mJ, Facility T would
benefit from having MIE testing data for a broader range of the
materials that are handled and processed. 

Facility T implemented many measures to identify and mitigate
combustible dust safety hazards and communicate them to employees. The
facility’s process hazard analyses thoroughly evaluated the likelihood
and severity of potential combustible dust incidents (among other types
of health and safety hazards), and multiple training courses
communicated potential hazards and mitigation measures to operators,
maintenance personnel, and other employees who might otherwise come into
contact with combustible dusts. 

Multiple processes at Facility T operate under inert (nitrogen)
atmospheres. This operation can be highly effective at preventing fires
and explosions, but it is essential that oxygen concentrations in these
processes remain safely below the LOC in order to prevent hazardous
conditions. At Facility T’s reactors, dust-laden air within the
reactor is pumped to continuous oxygen analyzers. While this process has
proven effective for ensuring oxygen concentrations do not exceed the
LOC, site visitors voiced some concern about sampling lines becoming
plugged. Facility T representatives were encouraged to refer to
specifications in Section 7.1.2.1 of the 2006 edition of NFPA 654 to
assess the reliability of their sampling systems that feed air from
inerted vessels to oxygen analyzers. 

Facility T handles several materials that have MIE values on the order
of 1 to 5 mJ, and are therefore extremely sensitive to ignition. The
fact that Facility T has apparently not experienced fires or explosions
caused by electrostatic discharge suggests that controls to date have
proven to be effective. As evidence of this, the processes toured by
site visitors had extensive grounding and bonding on most processing
equipment. However, site visitors suggested that the facility consider
additional evaluations to ensure that electrostatic discharges are
adequately controlled. Further research was encouraged to ensure that
anti-static bags used in Facility T’s plastic drums achieve the charge
retention times specified in NFPA 99 (see NFPA 99, Annex E.6.6.8.6.3)
(while still meeting site GMP requirements); and consideration should be
given to requiring employees who transfer dry materials in settings that
generate dust clouds to work with grounding straps, conductive shoes,
and possibly even fire-resistant garments. An alternate—and
preferred—solution would be to implement process modifications that
eliminate the need altogether for manual material transfer operations
that can potentially generate dust clouds. 

The dust collectors that site visitors viewed vary considerably in terms
of design and operation. The newer dust collectors appear to be most
advanced in terms of protection systems (e.g., explosion panels, fire
detection and suppression, no manifolded ductwork). For the older
systems, opportunities exist for minimizing potential combustible dust
hazards. For example, isolation systems might prove beneficial where
filtered exhaust air from dust collectors is returned to production
areas and where multiple production areas have air vented through
manifolded ductwork to single dust collectors; existing smoke detection
devices can be interlocked to abort gates in return air ducts, dampers
at inlets, and fire suppression systems in the dust collectors; and
explosion vents that do not currently discharge to the building exterior
can be replaced with flame arrestors or other technologies that would
not cause significant damage should deflagrations occur. FM standards
(see FM-76, section 2.3.3.2) and NFPA standards (see NFPA 654, section
7.13.1.5 and 7.1.4) provide further context on these issues. 

Multiple milling operations at Facility T are used to grind together
active ingredients and excipients. A potential ignition source in such
operations is tramp metal (e.g., a loose bolt, wire from sifting
screens) entering the milling operation. Most of Facility T’s milling
devices operate under inert atmospheres, but some do not. Use of
magnetic separators at locations upstream of the uncontrolled milling
devices can help reduce the risks of tramp metal acting as an ignition
source in these operations. 

Facility T has numerous other operations, each with different controls
for combustible dusts. Site visitors commended the facility for many of
its process safety efforts, but also noted some areas of improvement.
For example, the fluidized bed dryers were equipped with exhaust air
temperature sensors to detect potentially unsafe operating conditions,
but an added level of control would be to implement an upper-bound
temperature limit for the dryer itself and have this limit interlocked
to the nitrogen inerting system. Additionally, site visitors encouraged
facility representatives to work with their insurance underwriter to
confirm that wall explosion panels used throughout the facility were
installed correctly (i.e., using the appropriate bolts, collapsible
washers, and other components). 

Feedback to OSHA

At the end of the site visit, ERG asked representatives from Facility T
if they had any specific feedback for OSHA on combustible dust safety
issues. (Note: This site visit occurred after OSHA publicly announced
its intention to initiate a rulemaking on combustible dust [OSHA,
2009b], but before the agency convened its stakeholder meetings).
Facility T representatives offered the following responses:

Facility T representatives noted that pharmaceutical manufacturers are
subject to extensive regulation by FDA, OSHA, and various other
agencies. They encouraged OSHA to ensure that any requirements in its
pending combustible dust standard leave ample compliance options for
pharmaceutical manufacturers, while not complicating compliance with FDA
regulations. To illustrate their concern, FDA regulations already limit
the options that pharmaceutical manufacturers have for using plastic
bags to hold active ingredients and excipients. Should OSHA add
prescriptive requirements of its own (e.g., use of material with an
extremely low charge retention time), pharmaceutical manufacturers might
have extremely limited options—and possibly no options—for
purchasing compliant plastic bags.

Facility T representatives encouraged OSHA to identify and review
existing FDA regulations applicable to pharmaceutical manufacturers to
ensure that the combustible dust standard does not include conflicting
or unnecessary requirements. 

References

Babrauskas. 2003. Ignition Handbook. Fire Science Publishers: Issaquah,
WA. 

Bartknecht. 1990. Dust Explosions: Course, Prevention, and Protection.
Springer-Verlag.

Eckhoff, 2003. Dust Explosions in the Process Industries (3rd Edition).
R.K. Eckhoff. Gulf Professional Publishing, Elsevier Science:
Burlington, MA.

NFPA, 2008. NFPA 61: Standard for the Prevention of Fires and Dust
Explosions in Agricultural and Food Processing Facilities. 2008 Edition.
National Fire Protection Association. 

OSHA, 2009a. Hazard Communication Guidance for Combustible Dusts. OSHA
3371-08. 2009.
<http://www.osha.gov/Publications/3371combustible-dust.html>

OSHA, 2009b. U.S. Department of Labor’s OSHA announces rulemaking on
combustible dust hazards. U.S. Department of Labor, OSHA, Office of
Communications. National News Release: 09-475-NAT. April 29, 2009.

 

Table 1. Testing Data Provided by Facility T

Parameter	Active Ingredients	Excipients

	A	B	C	D	E	F

MIE (mJ)	1-3	<1	1-3	>10	>3	>10

Pmax (bar)	8.5	7.1	7.9	[no data]	[no data]	[no data]

(dP/dt)max	762	536	962	[no data]	[no data]	[no data]

Kst (bar-m/s)	207	146	261	200-300	200-300	75

Explosion class	St2	St1	St2	St2	St2	St1

MAIT (oF)	> 450	[no data]	[no data]	[no data]	[no data]	[no data]

MEC (g/m3)	[no data]	129	[no data]	100	30	60



Notes: 	The various materials’ names are not specified, per request of
Facility T.

	Table lists the complete set of testing data that were shared with site
visitors. Data on additional parameters and materials were not available
during the site visit. Entries of “no data” indicate that data were
not available at the time of the site visit. 

	Information was not available on the particle size distribution for
most of the materials that were tested. Material A in the table
reportedly consisted of particles smaller than 70 microns. 

		Parameters reported in this table:

			MEC = minimum explosible concentration

MIE = minimum ignition energy

			Pmax = maximum explosion pressure

			Kst = deflagration index

			(dP/dt)max = maximum rate of pressure rise

			MAIT = minimum auto-ignition temperature for dust cloud

Table 2. Testing Results for Samples Collected During the Site Visit

Parameter	Sample #2673	Sample #2674	Sample #2675

Description of material	Pharmaceutical #2 collected from blender #3
Pharmaceutical #1 collected from blender #1	Pharmaceutical #3 collected
from unspecified location

Particle size data 



	   % through 20 mesh	86%	100%	100%

   % through 40 mesh	67%	87%	100%

   % through 200 mesh	25%	17%	0%

Moisture content	1.8%	1.0%	2.0%

Explosive material?	Not tested	Not tested	Yes

Kst (bar-m/second)	Not tested	Not tested	12.5

Explosion severity index	1.84	1.14	Not tested

Class II dust?	Yes	Yes	Not tested



Notes:	See Section 4.1.2 for more information on the sampled materials
and where they were collected.

Refer to Attachment 1 for the original reports from OSHA’s analytical
laboratory and important disclaimers about use of these data (e.g.,
“it is possible that the material is hazardous under different
conditions; the results obtained from this equipment can not be used in
designing or engineering protective safety equipment”).

Per laboratory protocols, Sample #2675 was not analyzed for being a
Class II dust due to the insufficient amount of material in the sample
<200 mesh. 

Table 3. Comparison of Combustible Dust Hazard Information Presented on
MSDSs to Facility T Testing Data for Selected Materials

Material	Combustible Dust Hazard Information on MSDS	Relevant Testing
Data Generated by Facility T

Active ingredient	“This material is assumed to be combustible. As with
all dry powders, it is advisable to ground mechanical equipment in
contact with dry material to dissipate buildup of static electricity.”
MIE = 1-3 mJ

Pmax = 7.9 bar

Kst = 261 bar-m/s

(dP/dt)max = 962 bar/s

Dust explosion class = St2

Excipient	“Accumulation of overhead settled dust may form explosive
concentrations in air when disturbed and dispersed.” “According to
NFPA 68 (explosion venting guide), the hazard class of dust
deflagrations for [excipients] is ST-1, the lowest hazard class.” 	MIE
> 10 mJ

MEC = 100 g/m3

Kst = 200-300 bar-m/s

Dust explosion class = St2

Excipient	“This material in sufficient quantity and reduced particle
size is capable of creating a dust explosion.” “Use with adequate
ventilation. Minimize dust generation and accumulation.” 	MIE > 3 mJ

MEC = 30 g/m3

Kst = 200-300 bar-m/s

Dust explosion class = St2



Notes:	The column titled “combustible dust hazard information on
MSDS” presents all information documented on the MSDS related to
combustibility and explosibility. 

		Parameters reported in this table:

			MEC = minimum explosible concentration

MIE = minimum ignition energy

			Pmax = maximum explosion pressure

			Kst = deflagration index

			(dP/dt)max = maximum rate of pressure rise

Attachment 1. Testing Results Provided by OSHA’s Analytical
Laboratory

Notes: 

Refer to Section 4.1.2 for information on the materials sampled and how
they were collected. 

Table 2 summarizes the sampling results; note that the “Sample
Numbers” across the top of the table correspond to the “Submission
Numbers” in this attachment. 

As acknowledged in OSHA’s testing results presented throughout this
attachment: “The results obtained from this equipment can not be used
in designing or engineering protective safety equipment.” Further, it
is possible that some materials that were tested exhibit lesser or
greater explosion hazards under different conditions. 



 This section focuses on only those 21 dust collectors in areas that
site visitors evaluated. This tally does not include Facility T’s dust
collectors in production areas that the site visitors did not tour. It
also does not include a portable dust collector observed in the
tablet-forming process, because site visitors did not obtain detailed
information on this device’s operation. 

 Even though the testing laboratory and Facility T are both owned by the
same entity, Facility T pays for the costs of testing samples for
combustibility and explosibility parameters. 

 As described further below, the quantitative data on this particular
excipient were not consistent with Facility T’s testing data for the
same material.

 PAGE   

Site Visits Related to Combustible Dust – Facility T 

 PAGE   27 

Site Visits Related to Combustible Dust – Facility T 

 

