LifeSafety Newsletter – Summer 2011

QUARTERLY INFORMATION FROM THE LEADER IN DETECTION AND NOTIFICATION
SUMMER 2011
Sophisticated & Strategic
Priorities for Life Safety in Mission-Critical Facilities
Our smoke detectors protect the public.
Our waterflow detectors
protect their city.
Fire or accidental sprinkler activation,
the building needs to be protected.
Fire sprinkler systems are designed to minimize fire damage and protect
people and the places where they live and work. But if the sprinkler
system doesn’t operate as expected, the results can be costly and tragic.
With System Sensor waterflow detectors, if a sprinkler head is
activated and water begins to flow, a signal is sent to a fire alarm control
panel or notification device. This enables personnel to respond quickly,
minimizing damage from fire or the water used to put it out.
For over 25 years, System Sensor has provided
innovative products that save lives and protect
property. To learn more about our waterflow detectors
or our complete line of sprinkler monitoring products,
visit systemsensor.com/wf.
EDITOR’S LETTER
By Lisa Weller,
Senior Product Marketing Manager, System Sensor
A Call to Pre-Action
Taking action is good; taking pre-action is
absolutely essential.
A pre-action suppression system, which
keeps sprinkler pipes dry until a fire detection
system activates a control valve, is commonly
used in mission-critical facilities. As good as
dry- and wet-pipe sprinkler systems are at
protecting typical commercial settings, a false
discharge could be disastrous for sophisticated
equipment and hinder the critical processes the
facilities are performing.
Before a pre-action system activates, the
detection system must properly assess the
situation and then inform the system to release
water into the distribution pipes. But even before
that point, the fire system designer needs to
determine if that’s the right strategy for the
application. Designers need to prepare for the
worst, but understand what’s at stake before
IN THIS ISSUE
8
NFPA Standards
SUMMER 2011
4
Sophisticated
& Strategic
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implementing action plans – especially in missioncritical facilities.
This month’s cover feature and Ask the
Expert discuss relevant codes and the detectors
and other technology options for protecting
mission-critical facilities. For example, System
Sensor offers a variety of detection options –
from nuisance-immune spot detection that excels
at sensing the slow, smoldering fires typical of
data centers to aspirating smoke detectors that
provide the very early warning necessary to
mitigate risk in mission-critical spaces.
You can learn much more about which systems
arm you best in this issue. System Sensor is ready
whenever you are.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
Case Study
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LifeSafety Magazine is provided as a courtesy to our colleagues in the fire
and life safety community. While we make every attempt to ensure the
accuracy of all information contained herein, product specifications and
building codes are always subject to change. Under no circumstances
should product or code information published in LifeSafety Magazine be
considered a substitute for written instructions from the manufacturer or
Authority Having Jurisdiction. Always follow proper installation and
maintenance practices, including carefully reading and understanding
manufacturers’ instructions before attempting to install, operate or maintain
any life safety equipment.
Your thoughts and comments are welcome at [email protected]. For
more information on System Sensor products, call 1-800-736-7672 or visit
www.systemsensor.com.
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COVER STORY
Sophisticated & Strategic:
Fire and Life Safety
in Mission-Critical
Applications
To protect information assets, a fire protection strategy must incorporate
specific emergency identification and suppression alongside detection.
Mission-critical facilities, such as data
and telecommunications centers, must
maintain operations without interruption.
Mission continuity is assured for facilities
through the use of redundant power
supplies and mechanical systems, and
cutting-edge fire protection systems.
Fire in these facilities can threaten
the business and human life. Key to
defending against a catastrophe is a
sophisticated fire protection system that
integrates seamlessly with the entire
environment.
Fire protection for mission-critical
facilities can be complex and daunting.
System designs should be based on
a total fire protection approach through
which three conditions are met: Identify
the presence of a fire, communicate the
existence of that fire to the occupants
and proper authorities, and contain and
extinguish the fire, if possible. Being
familiar with all technologies associated
with fire detection, alarming, and
suppression is important to developing
a sound fire protection solution.
Fire Detection Strategies
There are many ways of detecting and
suppressing fires, but only a few should
be used for mission-critical applications.
For example, the main goal of the fire
protection system in a data center is
to get the fire under control without
disrupting the flow of business or
threatening occupants.
Spot Detection
For the purposes of protecting a
mission-critical facility, addressable
early warning smoke detectors and
heat detectors can be an option.
Because the airflows are rapid in
an area such as a data center, it is
important to realize the differences
between types of detectors.
Ionization smoke detectors are
quicker at detecting flaming fires, such
as those commonly found in chemical
storage areas, rather than slow,
smoldering fires that most typically
occur in data centers and telecom
equipment spaces. Ionization sensors
almost immediately recognize fires
characterized by combustion particles
from 0.01 to 0.3 microns. However,
ionization sensors offer limited or slower
capabilities when installed in areas with
high airflow – which is often the case in
these mission-critical environments.
Photoelectric smoke detectors,
however, quickly respond to smoldering
fires characterized by combustion
particles from 0.3 to 10.0 microns,
making these detectors more appropriate
for most mission-critical settings.
One solution to detect a broad
range of fires quickly would be a multicriteria detector that uses photoelectric
particulate detection in tandem with
sensors that detect other products of
combustion, such as carbon monoxide
(CO) and light (infrared). Together, these
signals are cross-referenced by an
onboard microprocessor that uses
algorithms to “process out” false alarms
while enhancing the response time to
real fires.
Another solution is to use intelligent
high-sensitivity detectors, which are very
similar to standard detectors except that
they employ a more highly advanced
detection method.
High-sensitivity spot detection
typically employs a focused laserbased source to achieve sensitivities
that are 100 times more sensitive than
standard addressable or conventional
infrared-based photoelectric smoke
detectors. They are designed to respond
to incipient fire conditions as low as
(continued on page 6)
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LifeSafety Magazine SUMMER 2011 System Sensor
COVER STORY
Sophisticated & Strategic
0.02% per-foot obscuration to provide
valuable time for personnel to investigate
the affected area and take appropriate
action to mitigate risk.
These detectors are addressable
and are able to send information to the
central control station, thereby pinpointing
the exact location of the smoke. Some can
automatically compensate for changes in
the environment, such as humidity and
dirt buildup. They can also be programmed
a fire detection panel, when necessary,
to raise an alarm.
These detectors communicate
information to a fire alarm control panel,
a software management system or a
building management system through
relays or another interface. With some
systems, e-mail updates can be sent to
appropriate personnel to communicate
alarm levels, urgent or minor faults, or
other status conditions via relays.
There are many ways of detecting and
suppressing fires, but only a few should
be used for mission-critical applications.
to be more sensitive during certain times
of the day. For instance, when workers
leave the area, sensitivity will increase.
High-sensitivity detectors are
commonly placed below raised floors, on
ceilings, and above drop-down ceilings,
as well as in air handling ducts to detect
possible fires within the HVAC system.
Aspirating Smoke Detection
Many air sampling smoke detectors can
also provide high-sensitivity detection.
Some systems can be up to 1,000 times
more sensitive than a standard photoelectric
or ionization smoke detector and are
capable of detecting byproducts of
combustion in concentrations as low as
0.00046% per-foot obscuration. This type
of detection provides advanced notification
so facility managers or other appropriate
personnel can intervene and take action
before a combustion event becomes
disastrous.
An aspiration system works by
drawing in smoke through a network of
piping via the aspirator (fan). The air sample
is then passed through a filter and into the
sensing chamber of the detector. Using
advanced sensing technology, the detector
analyzes the air sample and sends a
signal of airborne smoke intensity to a
remote or integrated display module and
6
The multiple warning levels of this
system can trigger different responses at
different stages of a fire, from controlling
air conditioning to suppression release.
To accommodate specific codes or
environments, alarm relays can be set
with 0 to 60 second delays.
Fire Suppression Systems
Although smoke detectors primarily alert
of a fire condition, in a mission-critical
facility, they may also be used to control the
release of fire suppression systems. Should
a fire occur, suppression systems are the
next line of protection and can quickly
extinguish the fire with minimal or no effect
on the operation. It is important to consider
the suppression system to be utilized.
Sprinkler Systems
Sprinkler systems, which are designed
specifically for protecting the structure of
the building, can be installed in four
different configurations: wet-pipe, dry-pipe,
deluge, and pre-action. The wet-pipe
system consists of a piping system
connected to a water source and filled
with water so that water discharges
immediately from sprinklers activated
by a fire. In general, wet-pipe sprinklers
are not recommended for mission-critical
facilities; however, depending on local fire
codes, they may be required.
A dry-pipe system is typically used in
areas subject to freezing and consists of
piping connected to a water source and
filled with air pressure supplied by a
compressor. When a sprinkler is activated,
the air is expelled first, allowing a special
check valve, called a dry pipe valve, to
operate. This allows water to flow into the
piping and out any open sprinklers. This,
too, is not ideal for mission-critical facilities.
A pre-action system is more common
in a mission-critical facility. “A pre-action
sprinkler system is one effective alternative
because of its dual action criteria,” says
Ramzi Namek, Director of Engineering for
Total Site Solutions, Columbia, Md. “The
pipe remains dry until the fire detection
system activates a control valve (located
outside the data center to avoid damage
from leaks), filling it with water.”
It consists of closed-type sprinkler
heads connected to a series of piping
arrangements. The system has a preaction valve that prevents the pipes from
filling with water during normal times. This
valve is held closed electrically, only being
released by activation of the detection
system (fire detectors) when an electrical
signal is sent to the releasing solenoid
valve. Upon receipt of the signal, which
could be from any of the sensors attached
to the system, an electrical mechanism
opens the pre-action valve, and the
pipelines fill with water under pressure.
The system will now function as a standard
wet-pipe system. The water tanks are
located away from the area, but are
readily accessible.
“Another important design
consideration to plan for is space for
suppression agent tanks. Some
suppression agents are stored in gas
form; others are stored as a liquid, which
can impact the number and size of tanks
required,” explains Namek.
Clean Agent Suppression
In addition to sprinkler systems, clean
agent suppression systems can extinguish
LifeSafety Magazine SUMMER 2011 System Sensor
fires in their incipient stage, well before
enough heat builds in a room to activate
a sprinkler system. When activated, these
waterless flame suppression systems
discharge as a gas. The gas reaches all
areas of the protected facility and leaves
no residue to damage sensitive equipment
or require costly cleanup. Clean agents
suppress fires by many methods, including
depleting the area of oxygen, interrupting
the chemical reactions occurring during
combustion, and absorbing heat.
“Clean agent systems typically use
(3M) Novec 1230™, (DuPont) FM-200™,
or (Ansul) Inergen. They combine the
benefits of clean agent systems and
active fire protection with people-safe,
clean, environmentally friendly
performance,” explains Eric Fournier,
Project Manager, Total Site Solutions.
Clean agent suppression systems,
protecting both the areas underneath and
above the raised floor, are the most
common method of fire protection for
Class C electrical hazards. “Raised floors
bring up some important issues with
regard to fire protection in mission-critical
facilities,” says Fournier. Spaces beneath
raised floors often experience many air
changes per hour, which presents a
difficult detection design.
“Because raised floors create a
completely separate plenum and pose
as much of a fire hazard as the numerous
pieces of computer equipment situated
on the raised floors,” Fournier continues,
“they must be protected with the same level
of fire protection as the space above.”
These clean agent suppression
systems, when controlled by an interface
with a high sensitivity smoke detection
system, suppress fires without damaging
IT equipment, and allow staff to get the
facility up and running faster.
Water
Tight
weatherproof
The only duct smoke detector that
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adjusts to fit any application.
For more information, visit systemsensor.com/flex
Regardless of which detectors or
systems are used in the fire and life safety
design in a mission-critical facility, all must
be networked into one central location.
Whether that is a series of panels or a
control center, there will be a vast amount
of equipment used – hundreds and
maybe thousands of devices, depending
upon the size of the facility. Programming
is the key to how well all the pieces come
together. The outcome for a fire and life
safety system within a mission-critical
system remains: to minimize or prevent
a fire event in order to maintain constant
operation and protect occupants.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
ASK THE EXPERT By Jonathan R. Hart
NFPA Standards Specifically
Cover IT Equipment, Telecom
Jonathan R. Hart, Associate Fire Protection Engineer with the National Fire Protection Association,
is responsible for documents addressing information technology equipment, telecommunication
facilities, wet and dry chemical extinguishing systems, explosion protection, commercial
cooking systems, fire safety and emergency symbols, and water mist fire protection systems.
Hart holds a B.S. degree in Mechanical Engineering from Worcester Polytechnic Institute (WPI)
and is finishing work toward an M.S. degree in Fire Protection Engineering.
What fire and life safety codes
relate to a mission-critical facility?
NFPA 75, Standard for the Protection of
Information Technology (IT) Information
Equipment, and NFPA 76, Standard for
the Fire Protection of Telecommunications
Facilities, are the standards that pertain
specifically to the protection of IT
equipment, IT equipment areas, and
telecom facilities. The rest of the facility
will be designed to the applicable
codes and standards for hazards other
than fire and life safety.
The purpose of NFPA 75 is to set
forth the minimum requirements for the
protection of IT equipment and IT
equipment areas from damage by fire
or its associated effects, namely smoke
corrosion, heat, and water. Chapter 4 of the standard addresses
Risk Consideration. It states in section
4.1 that “the following factors shall be
considered in determination of the
need for protecting the environment,
equipment, function, programming,
records, and supplies: (1) Life safety
aspects of the function (e.g., process
controls, air traffic controls), (2) Fire
threat of the installation to occupants
or exposed property, (3) Economic
loss from the loss of function or loss of
records, (4) Economic loss from value
of the equipment, (5) Regulatory impact,
and (6) Reputation impact.”
The following chapters address
building construction, materials and
equipment permitted in the IT equipment
area, the construction of IT equipment,
fire protection and detection equipment,
records kept or stored in IT equipment
rooms, utilities, and finally, emergency
and recovery procedures.
NFPA 76 provides the requirements
for fire protection of telecom facilities
where telecom services such as
telephone (landline, wireless) transmission,
data transmission, voice-over Internet
protocol (VoIP) transmission, and video
transmission are rendered to the public.
Telecom facilities include signalprocessing equipment areas, cable
entrance facility areas, power areas,
main distribution frame areas, standby
engine areas used to run standby
power, technical support areas,
administrative areas, and building
services and support areas occupied
by a telecom service provider.
The purpose of the standard is
to provide a reasonable level of fire
protection in telecom facilities, to
provide a reasonable level of life safety
for the occupants, and to protect
equipment and service continuity. NFPA
76 is intended to avoid requirements
that could involve unnecessary
complications for or interference with
the normal use, occupancy, and
operations of telecom facilities and
equipment.
Chapter 4 of this standard also
addresses Risk Considerations. Section
4.1 Risk Factors reads:
Fire protection programs for
telecommunications facilities shall be
determined based on an evaluation of
the risks and hazards associated with
the site and services provided from the
facility and the business continuity
planning and disaster restoration
capabilities of the telecommunications
service provider specific to the site.
4.1.1 Fire protection programs
shall be established with consideration
given to the following factors:
(1) Exposure threat to facility
occupants, the general public, and
exposed property from a fire occurring
at, adjacent to, or within the facility.
(2) The importance of telecommunications service continuity
in supporting public safety through
emergency communications (such as
911), national defense communications
requirements, video transmission of
critical medical operations, and other
vital data.
(3) Methods employed by a service
provider, as part of a risk management
or business continuity strategy, that
allow service to remain viable during
and after an event or to be replaced
or restored within a reasonable period
post-event.
(4) The potential for a given
protection strategy to result in a service
disruption or inhibit the ability of the
service provider to restore service in
a timely manner post-event.
Section 4.2 of the standard
(continued on page 10)
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LifeSafety Magazine SUMMER 2011 System Sensor
“...information sent
via telephone,
Internet and similar
transmission
methods bring to
bear the need to
keep the routes that
information travels
up and running...”
— Jonathan R. Hart
Associate Fire Protection
Engineer, NFPA
ASK THE EXPERT
NFPA Standards
continues with this method of characterizing
the risk considerations in order to provide
the most suitable design.
The following three chapters address
performance-based design approaches,
prescriptive-based design approaches,
and redundant-or-replacement-based
design approaches, respectively. The
subsequent chapters detail the requirements
for fire protection elements, fire prevention,
pre-fire planning, damage control, and
emergency recovery.
Please explain the significance
of NFPA 75 and 76.
These documents have and continue to
become more and more important as
society grows reliant on what these
defense systems, among other critical
information. Data communications that
are protected include wired-line, wireless
(GSM, WiFi, etc.), satellite, radio, Internet,
cable, and air traffic control.
How do the standards apply to
different areas within a missioncritical facility?
NFPA 75 only applies to the protection
of IT equipment and IT equipment areas.
The rest of the facility will be designed
to the applicable codes and standards.
NFPA 76 simply requires that telecom
facilities be separated from the rest of the
building by two-hour fire resistance-rated
partitions. The standard contains additional
conditions for telecom facilities housed in
“If you think of how many of our work and
personal records, everyday use files and
information are accessible online through
centralized data repositories, you can
quickly see the importance of NFPA 75.” Editor’s Note: This month’s Ask the Expert has
been edited for length. Read the complete
column at systemsensor.com/ls. For more
information on NFPA Codes and Standards,
including NFPA 72®, NFPA 75® and NFPA
76®, visit www.nfpa.org/codes.
NFPA 72® , NFPA 75® & NFPA 76® are registered trademarks of
the National Fire Protection Association.
— Jonathan R. Hart, Associate Fire Protection Engineer, NFPA
documents are designed to protect. If
you think of how many of our work and
personal records, everyday use files and
information are accessible online through
centralized data repositories, you can
quickly see the importance of NFPA 75.
Likewise, information sent via telephone,
Internet and similar transmission methods
bring to bear the need to keep the routes
that information travels up and running,
which is a main goal of NFPA 76.
A small sampling of what is protected
by NFPA 75 and NFPA 76 includes data
storage/retrieval systems, ranging from
criminal and medical records, financial
records and transactions, insurance and
legal records, and registration databases.
Data processing systems are protected,
including background checks, prescription
compatibility, weather modeling, and
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NFPA 76 requires Very Early
Warning Fire Detection (VEWFD) for
rooms containing over 2,500 square feet
of signal-processing equipment areas
and Early Warning Fire Detection (EWFD)
systems for facilities containing less that
2,500 square feet of signal-processing
equipment. Raised floors require fire
detection depending on their use and
the detection used in the area above
them. The standard requires that EWFD
and VEWFD use sensors or ports with
spacing that is less than normally required
by NFPA 72. Specific requirements for
each type of detector are contained in
Section 8.5 of the standard.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
multiple tenant buildings that require either
specific building construction types AND
require automatic suppression, or limit
them to one story.
How do the standards address
instances that go beyond
traditional fire detection?
NFPA 75 requires the installation of
automatic detection equipment to provide
early warning of fire. This needs to be a
listed smoke detection-type system installed
and maintained in accordance with NFPA
72®, National Fire Alarm and Signaling
Code. The automatic detection systems
are required to be located at ceiling level
throughout the IT equipment area, below
raised floors containing cables, and above
suspended ceilings that recirculate air.
LifeSafety Magazine SUMMER 2011 System Sensor
Breathe easy.
System Sensor offers aspirating smoke detection.
To keep your mission-critical facility up and running, you need to manage issues rather than
react to emergencies. The FAAST™ Fire Alarm Aspiration Sensing Technology offers the most
early and accurate fire detection available, so you can mitigate risks before disaster strikes.
Learn more at systemsensor.com/faast.
CASE STUDY
Science’s Answer to
Critical Protection
The Science Museum of Minnesota installed FAAST™ Fire Alarm Aspiration Sensing
Technology for maximum protection in its hazardous fluids and equipment storage area.
Fire protection for a
mission-critical facility such
as the Science Museum of
Minnesota is not limited to the exhibit
space; it extends to other buildings.
For instance, maintaining a museum
with irreplaceable and invaluable
artifacts requires sophisticated
equipment, many cleaning and
maintenance supplies and a first-rate
storage facility to service the museum.
“Because of the proximity of the
storage facility to the museum, fire
“The storage area’s unusual
concrete ceiling,” Hedin says, “consists
of 18 pre-cast double tee ceiling
panels that are roughly 3 ft. x 4 ft. x 25
ft. each.” Smoke easily could collect
in the concave-shaped ceiling before
an alarm would be signaled. Further
complicating fire detection, the storage
facility can be a dirty and dusty
environment.
“We researched various methods
of detection and needed a very early
warning system,” Hedin continues.
“We recommended System Sensor’s FAAST system, for
a primary reason, to ensure that the high nuisance dust
factor in the storage area does not cause an alarm state.”
— Dan Westberg, VP of Low Voltage Contractors
safety and protection have to be top
rated,” says Don Hedin, Assistant
Director of Facilities at the Science
Museum of Minnesota in St. Paul,
Minn. That led the museum to install
System Sensor’s FAAST Fire Alarm
Aspiration Sensing Technology in its
storage facility.
“We store fuel and other volatile
liquids in secured safety cabinets,” he
continues. “We also store our tractors,
garden and snow removal equipment,
vehicles and other maintenance
equipment there.” The 35 sq. ft.
locked storage area is located in
the museum’s adjoining 810-vehicle
parking structure.
12
“We didn’t want to trigger unnecessary
false alarms, disturb our visitors or
possibly endanger our priceless
exhibits. We chose aspiration
technology not only for the safety
factor, but for cost savings. The
museum couldn’t jeopardize its
mission-critical exhibits by triggering
nuisance false alarms because of the
storage room’s dusty environment.”
Hedin relied on Dan Westberg,
Vice President of Low Voltage
Contractors (LVC) of Minneapolis, to
select a fire alarm aspirating system.
“We recommended System Sensor’s
FAAST system, for a primary reason,
to ensure that the high nuisance dust
factor in the storage area does not
cause an alarm state,” Westberg says.
The piping and system installation
took only eight hours as only one unit
was installed, as opposed to installation
of multiple area detectors. The system
was tested and approved by the city
of St. Paul.
The FAAST system is monitored
by a NOTIFIER® control panel, which
is in the museum’s security office.
Because of the FAAST’s tolerance to
highly dusty and dirty environments,
it reduces nuisance alarms.
For anyone hesitant to use
aspirating detection based on early
generation products from other
manufacturers that did not deliver
as promised, the technology has
been perfected to the point where it
is now a “go to” system. According
to Westberg, aspiration detection
requests have been growing steadily.
“Aspiration detection is a must in fire
protection design,” he concludes.
For more information, fill out
the enclosed business reply card
or go to systemsensor.com/ls/brc.
Editor’s Note: This month’s Case Study
column has been edited for length. To
read the complete case study, go to
systemsensor.com/ls.
LifeSafety Magazine SUMMER 2011 System Sensor
Science
Museum of
Minnesota
St. Paul, Minnesota
Connected storage area
Volatile Materials
Challenging architecture
Dusty environment
Very Early Warning Required
FAAST 8100
COMING SOON
Plastic Weatherproof Back Boxes
This summer, System Sensor will begin
shipping plastic weatherproof back
boxes with outdoor horns, strobes, and
horn strobes. These new back boxes
are made from lightweight plastic that
makes for an easier install. In addition,
the new materials protect against
corrosion and provide enhanced
resistance to UV-induced fading. And
with removable mounting ears, these
back boxes can be used with cages
or other external device protection
products to obtain a cleaner look.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
FEATURED PRODUCT
Multi-Criteria Detection for
Mission-Critical Applications
FRO
The award-winning Advanced MultiCriteria Fire Detector combines four
sensing technologies — smoke, carbon
monoxide, heat, and light — with
intelligent algorithms to maintain the
highest sensitivity to real fire while
rejecting nuisance conditions. Beyond
applications with persistent nuisance
conditions, the Advanced Multi-Criteria
Fire Detector is ideal for many missioncritical applications that cannot tolerate
nuisance alarms at any time.
For example, chemical and
pharmaceutical manufacturers have
facilities in which nuisance alarms can
lead to significant revenue losses from
shutdowns that result in lost production
time and raw materials that must be
scrapped after a stop/restart. Likewise,
financial institutions can sustain huge
financial losses from downtime resulting
from nuisance alarms. Other applications
with mission-critical areas that cannot
tolerate nuisances include medical
facilities and data centers.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
NT V
I EW
SYSTEM SENSOR ONLINE
New CAD File Download Page
at SystemSensor.com
Do you need CAD files for System
Sensor products for your project plan?
Our new CAD download page makes it
easy by enabling you to select and
download all the CAD files you need
from a single page.
To download CAD files, simply go
to systemsensor.com/cad and select
the checkboxes for the model numbers
BAC
14
K VIE
W
you need. Then press the “Submit for
download” button at the top or bottom
of the page to download a zipped
archive of the CAD files you selected.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
ISO V
LifeSafety Magazine SUMMER 2011 System Sensor
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CODES AND STANDARDS
Code Speaks Louder About Intelligibility
NFPA 72-2010 refines and more carefully defines the concept of intelligibility.
NFPA 72-2010 code focuses
on intelligibility and the need for
voice evacuation systems to
provide alerts with information that is
audible and understandable. It defines
intelligibility as the quality or condition of
being intelligible (3.3.124) and intelligible
as capable of being understood,
comprehensible, clear (3.3.126). The
code also adds a key term, ADS, that
helps to clarify intelligibility requirements.
Acoustically Distinguishable Space
(ADS) is an emergency communication
system (ECS) notification zone, or
subdivision thereof, that might be an
enclosed or otherwise physically defined
space, or that might be distinguished
from other spaces due to acoustical,
environmental, or use characteristics,
such as reverberation time and ambient
sound pressure level (3.3.2).
Establishing ADSs is foundational to
planning an intelligible system. An ADS is
any space that can or cannot have
intelligibility. The ADS needs to be
determined at the beginning of the project.
In Chapter 18 – Notification
Appliances, NFPA 72-2010 states that
within the ADS, where intelligibility is
required, voice systems shall reproduce
prerecorded, synthesized, or live messages
with voice intelligibility (18.4.10). In each of
these spaces, measuring for intelligibility
may or may not be required.
ADSs shall be determined by the
designer during the planning and design
of all ECS (18.4.10.1). Each ADS shall be
identified as requiring or not requiring
intelligibility (18.4.10.2). Where an ADS is
required by the authority having jurisdiction,
ADS assignments shall be submitted for
review and approval (18.4.10.3).
Chapter 24 – Emergency
Communication System provides
requirements for designing an intelligible
voice evacuation system for an ECS. The
speaker layout of the system shall be
designed to ensure intelligibility and
audibility; intelligibility shall first be
determined by ensuring that all areas in
the building have the required level of
audibility; and the design shall incorporate
speaker placement to provide intelligibility
(24.4.1.2.2.1).
To meet NFPA requirements, the
following is needed: the average ambient
background noise level of the area; room
characteristics such as length, width, and
height of the ceiling and reflectivity of the
surfaces in the room; and the coverage
angle or polar plot of the speaker.
Annex D provides guidance on the
planning, design, installation, and testing
of voice systems. The annex also contains
recommendations for testing intelligibility
methods and requirements for testing.
When testing intelligibility, Annex
D.2.4.1 recommends that 90 percent of all
measurements in an ADS meet required
intelligibility scores to be considered
acceptable. These scores fall on the lower
end of the intelligibility scale: a measured
Speech Transmission Index scale (STI) of
not less than 0.45 (0.65 CIS – Common
Intelligibility Scale) or an average STI of
not less than 0.50 (0.70 CIS).
Designing a system to meet current
intelligibility requirements can be
challenging because of the many factors
that influence intelligibility, such as room
dimensions, building materials, ambient
sound, and usage. However, the NFPA
code has been designed to limit the
complexity of these systems by
minimizing the potential for over-design.
Therefore, the best approach is to be
familiar with NFPA requirements and
definitions before attempting to design a
voice evacuation system for intelligibility.
For more information, fill out the
enclosed business reply card or go to
systemsensor.com/ls/brc.
LifeSafety Magazine SUMMER 2011 System Sensor
Applying NFPA 72-2010
Step 1
ADS Assigned
Step 2
Intelligibility
Required?
Step 3
Measurement
Required?
No
Complete
Yes
No
Complete
Yes
Step 4
Subject-Based
Measurement
Objective
Measurement
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