out on an industrial facility project, there are questions to ask to
get the "lay of the land.” One of the first pieces of information to
learn is the process description – starting with the incoming raw
materials (how they are delivered, stored, and transferred into the
batch or continuous process areas of the facility).
next step of the study of the process is to understand the conditions.
Possible hazards stem from how the raw materials are stored and
transferred to the manufacturing process, whether the process is a
chemical synthesis or simply a mixing process, the temperature and
pressure conditions, the duration of the process and what role the
operations staff plays. Other factors to consider include whether there
is a purification or drying step, how the final product is packaged and
stored, and how the finished goods are stored.
is important to develop an understanding of the unit operations and
processes at the facility. This includes a study of process &
instrumentation diagrams (P&IDs) as well as narrative process
descriptions. A full listing of the hazardous materials – with chemical
names, solution concentrations, and container sizes and types – is
essential to begin the analysis.
CODES & STANDARDS
codes and standards on the industrial/chemical side contain applicable
requirements and valuable information. One of the roles of the FPE is to
identify the applicable codes and standards for a specific industrial
process and help a facility operator understand how they apply to a
codes for industrial/ chemical facilities contain requirements that
connect directly with an understanding of the engineering basis for
manufacturing processes and facility design. An existing facility may
not be able to implement all of the applicable requirements immediately
or even in the first year after a survey or audit. One of the most
important tasks when analyzing an industrial facility is to help
categorize recommendations into priorities so facility managers can put
together a compliance plan. Relevant factors that may influence the
compliance plan include the source of the requirement (e.g., code,
standard, or underwriting requirement), how the requirement applies to
the specific site condition, and recommended options and solutions.
requirements also can have a significant impact on the design and
operation of an industrial operation. The FM Global datasheets provide
requirements for many types of industrial facilities. Underwriting
requirements are often a good source of information for a specific
hazard or type of industrial process and augment the available codes and
FM Global Datasheets 7-441 and 7-912
contain technical information that can be utilized during the design
process. For example, a site layout that includes a chemical process
will have specific set-back and separation distance requirements based
on the hazard involved. Similarly, a hydrogen storage and dispensing
installation can turn to the FM Global recommendations and loss history
to address certain hazard concerns, such as exposure to adjacent
equipment and protection of process piping systems. Local fire officials
often put confidence in underwriting requirements as an aid to their
understanding and level of comfort that a complex industrial or chemical
process is being adequately reviewed.
FIRE SUPPRESSION AND DETECTION SYSTEMS
are several factors to consider when designing a fire suppression or
detection system in an industrial facility. Many facilities have
multiple chemical processes that may each have a different set of hazard
criteria. What this means is that the fire suppression and detection
system design approaches for adjacent areas in a plant may be different.
is necessary to be aware of these conditions and take care not to
specify a system that may interfere with the effectiveness of a nearby
system. Also, one may deal with classes of materials that are
For example, a process
enclosure containing water-reactive materials may be adjacent to a
process that handles pyrophoric gases. The protection schemes for these
two processes are quite different. It may be necessary to protect the
water-reactive process enclosures with CO2 and simultaneously cool adjacent outdoor pyrophoric-containing equipment with water spray.
suppression approach and agent should be developed by considering the
compatibility of materials in storage and in open or closed process
equipment. The Guidelines for Fire Protection in Chemical, Petrochemical, and Hydrocarbon Processing Facilities3 provides information on fire suppression and detection approaches for an industrial site.
initial step in the evaluation of hydraulic demand for an industrial
plant is a hazard analysis of the materials being stored and processed.
For water-based fire suppression systems, the hazard analysis provides
an estimate of the size of the site fire water loop, as well as any fire
pumps and fire water storage tanks.
technologies in fire detection/ suppression systems provide additional
options. There are more gas and flame detectors available than in the
past, which enables the fire protection engineer to specify additional
methods for detection of gases. Also, for some of the water-reactive
chemicals, compatible automatic suppression systems are now available.
technologies such as water mist suppression are an addition for
facilities that need to contain and treat sprinkler discharge. For
example, bio-containment facilities require drainage of sprinkler
discharge to a biological "kill” system in the building prior to
discharge to the municipal sewer.4
use of alternate fire suppression agents can require a
performance-based analysis that compares the combustible loading in the
process area against the performance of the suppression system. Biosafety in Microbiological and Biomedical Laboratories (BMBL)4 includes guidelines for fire protection system design in bio-containment facilities.
type of product or process condition in the facility will impact the
passive and active fire protection systems. For example, a facility that
handles pyrophoric gases will likely require a Group H-2 occupancy
classification per the International Building Code (IBC).5 The
corresponding fire resistance of the building will be impacted. The best
suppression method is often to shut off the gas flow via an interlock
with a gas and flame detection system.
material solvent distribution and waste collection systems are becoming
more commonplace, even in laboratory buildings. Fire protection
considerations for such installations include leak detection for
transfer piping and organic vapor (LEL) detection at the point of use,
as well as static discharge concerns. Considerations that should be
addressed include the rate of transfer of the flammable liquid, the
propensity to create a static charge, how the static charge could be
equalized and dissipated, and what type of pump or inert gas will be
A plant with a bulk
combustible liquid process may need a foam/water suppression system for
both external (monitors) and internal tank protect ion ( foam pourers).
The analysis should look at conditions such as the chemical composition
and physical properties of the process fluids and the type of fire
events that could occur. An understanding of the process chemistry and
operating conditions is necessary for sizing and placement of equipment
such as external tank monitors, internal nozzles or pourers, and
systems may be needed for industrial facilities. They provide a
controlled working environment for the plant operations staff and
minimize the risks to exiting occupants in a spill, release, or fire
event. To this end, there are often requirements for dedicated exhaust
systems from certain areas, with limitations on the routing of the
exhaust to the outdoors. Also, some process areas may need low elevation
supply and exhaust to get a complete air change for vapors that are
heavier than air.5,6
fire hazard analysis, such as calculation of flammable vapor
concentrations in dispensing and processing areas, can also be
performed. The industry standard is to remain below 25% of the lower
explosive limit (LEL).5,6,7 However, facility constraints may
result in scenarios where concentrations can exceed 25% of the LEL. For
example, certain pharmaceutical processes require re-circulation of the
room exhaust to maintain area cleanliness levels. Calculation of the
vapor concentration with exhaust recirculation can be done and may
indicate that 25% of the LEL will be exceeded. This may be acceptable,
provided that an explosion prevention method is employed. Possible
approaches could include LEL detection interlocked with a purge exhaust
rate. Discussions with facility staff are needed, so there is agreement
on alarm and interlock points, as well as emergency evacuation and fire
as real-time exhaust monitoring can automatically alert the facility
staff to a chemical release or loss of ventilation, initiate their
emergency response, and log the data and time to help determine the
cause of the event.
ELECTRICAL AND POWER SYSTEMS
of the most common discussions in industrial facility design concerns
the electrical and power systems. There should be a clear agreement on
what systems should be on emergency or standby power, and for how long.
It may be necessary for both supply and exhaust to be on emergency power
to allow for continuous air circulation and to meet door opening force
requirements. If only the exhaust is on the emergency generator, the
reduction of vapor concentration will be limited, and egress could be
Industrial plants have
many hazardous electrical classification challenges, where equipment may
not be procured as Class I or II, Division 1 or 2, and meet the
requirements of the National Electrical Code.8 NFPA 4979 and NFPA 49910 are valuable tools that are used to delineate the extent of electrically classified areas. NFPA 49611 is another reference for purged or pressurized enclosures, such as control rooms on the interior of a plant.
CONTROLS AND INTERLOCKS
industrial facility has many special detection devices, alarms, and
interlocks. The key is to understand and document how the controls and
interlocks will function and what will occur when they are activated.
Documentation should address the alarm points, who responds to an alarm,
the response procedure, whether the entire facility should be evacuated
and, if so, whether workers need to secure processes and hazardous
materials prior to leaving the building.
and controls need to correspond to the specific hazard. For example, if
one specifies a flame detector and interlocks for hydrogen dispensing,
the detector must be capable of seeing the hydrogen flame in the UV/IR
As a follow-up to
industrial fire protection design work, a site visit is often conducted
to review controls and interlocks and verify that they meet the
requirements of the initial hazard analysis and specialty code review.
It is good practice for the fire protection engineer to witness the
acceptance testing of these systems and confirm that they are consistent
with the sequence of operations and performance that were recommended.
Jonathan M. Eisenberg is with Rolf Jensen & Associates, Inc.
- Property Loss Prevention Data Sheet 7-44, "Spacing of Facilities in Outdoor Chemical Processing Plants,” FM Global, Norwood, MA, 2012.
- Property Loss Prevention Data Sheet 7-91, "Hydrogen,” FM Global, Norwood, MA, 2012.
- Guidelines for Fire Protection in Chemical, Petrochemical, and Hydrocarbon Processing Facilities, American Institute of Chemical Engineers, New York, 2003.
- Biosafety in Microbiological and Biomedical Laboratories, U.S. Department of Health and Human Services, Bethesda, MD, 2009.
- International Building Code, International Code Council, Washington, DC, 2012.
- International Mechanical Code, International Code Council, Washington, DC, 2012.
- NFPA 69, Standard on Explosion Prevention Systems, National Fire Protection Agency, Quincy, MA, 2014
- NFPA 70, National Electric Code, National Fire Protection Association, Quincy, MA, 2014.
- NFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, National Fire Protection Association, Quincy, MA, 2012.
- NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, National Fire Protection Association, Quincy, MA, 2013.
- NFPA 496, Standard for Purged and Pressurized Enclosures for Electrical Equipment, National Fire Protection Association, Quincy, MA, 2013.