Low Frequencies
Historic Dallas hotel gets a fire alarm system makeover
- By Kris Cahill
- Jun 01, 2016
Known for offering big comfort and
style, SpringHill Suites Dallas Downtown/
West End delivers on the motto
“Everything is Bigger in Texas.”
Located in the historic West End of
downtown Dallas, the 10-story hotel features 148
guest rooms with a sophisticated and contemporary
cowboy ambiance. The hotel recently needed a new
fire system panel, which in turn required the entire fire
system to be brought up to current code.
Fire and Life Safety America (FLSA), located in
Euless, Texas, was asked to evaluate the existing fire
panel, but the city of Dallas requires fire systems to be
brought up to code when any component is replaced.
Because the city recently adopted the 2013 Edition of
NFPA 72 and the IBC 2012/IFC 2012, it was necessary
to upgrade the voice system and notification devices
in addition to the fire alarm control panel.
“The city of Dallas’s new building code requirements
stated that with any fire system upgrade or replacement,
the entire building fire system has to be brought up to current code,” said Carl
Ball, alarm and special hazards sales
and design for FLSA. “Recommending
the replacement of the existing, obsolete
fire panel triggered this requirement
to bring the entire building up to
current NFPA code.”
This fire system upgrade made
Springhill Suites one of the first buildings
in Dallas to comply with the
NFPA 72:2013 low-frequency requirements
for sleeping spaces for protected
premise fire alarm systems.
The new requirement covers how
to alert sleeping people in commercial
sleeping areas, such as hotels. The requirement
specifies that an audible device
in the space must produce an alarm
tone at a lower frequency centered on
520 Hz, and must be of a square wave
form. NFPA research found that a lower
frequency, specifically 520Hz and of
a square wave form, was more effective
in waking individuals, including those
with mild to severe hearing loss.
A square wave is different from a
pure tone signal in that a square wave
consists of a specific fundamental
frequency and an infinite number of
subsequent peaks at odd-numbered
harmonics. The low frequency tone
benefits not only the hard of hearing,
but also children, deep sleepers, and
people impaired by alcohol or medications.
The tone gives these individuals
a higher chance of waking when a fire
occurs.
It’s important to remember that
fire alarm systems and smoke alarms
are just as valuable for people when
they’re asleep as they are for when
they’re awake. This is illustrated in a
2010 study by the U.S. Fire Administration,
which determined that 50 percent
of deaths as a result of residential fires
occur between 10 p.m. and 6 a.m. This
emphasizes the importance of maximizing
those crucial seconds between
the initial sounding of an alarm and
waking individuals so that they can react
appropriately when there is a building
emergency.
Specifically, the low frequency sleeping
space requirements within NFPA
72:2013 edition are discussed in the following
NFPA 72 chapters:
- Chapter 18 (Protected Premise Fire
Alarm Systems) – Requires low frequency
notification in every sleeping
space
- Chapter 24 (Emergency Communication
Systems) – Requires a low
frequency signal in sleeping areas
to be followed by a voice message in
sleeping spaces
- Chapter 29 (Household Fire Alarm
Systems) – Requires low frequency
notification only in sleeping spaces
for those classified as having mild-tosevere
hearing loss, where governed
by law or code, or volunteered to
provide a means for such individuals.
- Many jurisdictions in the United
States such as Dallas have adopted
IBC and IFC 2012, which indirectly
reference NFPA 72: 2013, which requires
a low frequency tone in certain
newly constructed Group-R
occupancies. These are the applications
that may be impacted:
- Transient lodging spaces/hotels/
motels.
- College and university dormitories.
- Assisted living facilities.
- Apartments and condominiums.
ADVANCED SOLUTIONS
In order to meet this important code requirement,
SpringHill Suites chose the
Honeywell Farenhyt Series IFP 2000ECS
intelligent fire alarm control panel with
voice system and corresponding UL
low frequency listed devices, such as
Honeywell Farenhyt Series amplifiers with
incorporated low frequency tones, System
Sensor high-fidelity speakers and
speaker strobes, and Farenhyt intelligent
low frequency sounder bases.
“To meet the new low frequency
code requirement we had to have low
frequency sounder bases on the detectors
in each room, as well as speakers,”
said Dennis Piekarski, ASH operations
manager at FLSA. The low frequency
sounder bases are designed to be aesthetically
pleasing, making them ideal
for applications like hotels where appearance
is critical.
Two sounder bases were installed
in each room, a total of 296 low frequency
sounder bases, which required
careful wiring consideration. To cut
down on some of the conduit without
interrupting wire requirements and
circuit integrity, the FLSA fire and
life safety system design called for the
placement of a power supply and an
amplifier on each floor.
“The system was designed so that if
a detector in an individual room went
into alarm, only the sounder base in
that room will activate,” Peikarski said.
“If an alarm condition is triggered by
any device in the common areas of the
hotel, the voice system activates on the
floor of the alarm as well as the floor above and below the alarm.
“The system also has capacities of
an ‘all call’ manual page throughout the
entire hotel, including all guest rooms
and all common areas,” Piekarski said.
POWER SUPPLY
CONSIDERATIONS
With the comparatively high current
draw of low frequency 520 Hz devices,
the selection of the power supply and
accurate voltage drop calculations are
critical to ensuring adequate current
to the loop. The code does not preclude
the use of low frequency devices
throughout a building, including nonsleeping
spaces, but the high current
draw of the devices can make this a
higher cost approach.
Having a power supply on each floor
helped to distribute power throughout
the building.
“The low frequency bases consume
more power than standard bases,”
Ball said. “When there are many in a
building, the main design criteria are
to be aware of how much power they
pull collectively. In this case, having
a power supply on each floor worked
out really well.”
System Sensor and Honeywell Farenhyt Series low-frequency solutions
worked well for this project because
they provided the required audible notification
while also being easy to install.
Due to the quantity of devices, ease of
installation was a critical feature in this
case. The System Sensor low frequency
sounders, sounder strobes, and sounder
bases meet the NFPA 72: 2010/2013 low
frequency requirements for commercial
sleeping spaces, and they can be interconnected
with our non-low frequency
sounders to provide synchronization
throughout the notification zone.
What’s more, when the hotel installed
a sprinkler system in 2011, the
corresponding sprinkler piping was
placed in the soffits.
“Although it posed a design challenge,
this was the perfect space to run
our wires so we wouldn’t have to run
exposed wires and conduit throughout
the building,” Piekarski said, “making
it more aesthetically pleasing.”
This article originally appeared in the June 2016 issue of Security Today.