NFPA Journal - Winter 2022 - 38

In Compliance
NFPA 72
Fire alarms, signaling,
and emergency communications
Understanding
emergency responder
communication
enhancement systems
By Jonathan Hart
I
n recent months,
fires have occurred in
mercantile occupancies
that have raised questions
on the timing of
sprinkler actuation and fire alarm
notification, a fundamental aspect of
NFPA 72®
Signaling Code®
, National Fire Alarm and
.
One example was captured in a
video-shot on a smart phone and
widely shared on social media-of
a fire that started in a retail store.
The video was taken by an occupant
inside the building prior to egressing
and shows sprinklers operating
and controlling the fire. The video was
shared among multiple social media
platforms, and everywhere I saw it I
noticed the same types of comments
from viewers who may not understand
how fire protection and life safety
systems operate. The comment I saw
the most was, " Why isnt the fire alarm
going off if there is a fire? "
The answer is that the stores fire
alarm system might not have been
required to provide occupant notification
based on sprinkler actuation.
NFPA 72 permits up to a 100-second
delay between sprinkler waterflow and
occupant notification; it is likely that
the fire alarm did in fact notify the
occupants in that video, with notification
occurring after a delay of not more
than 100 seconds. Its possible the video
was taken before that delay was over.
The allowance for a 100-second
delay before the actuation of alarm
notification appliances is broken
down into two requirements. The
first requirement is related to the
38 | NFPA JOURNAL * WINTER 2022
waterflow initiating device and found
in Section 17.13 of NFPA 72. Subsection
17.13.2 requires that the waterflow
initiating device activate within 90
seconds after a flow occurs that is
equal to or greater than the flow from
a single sprinkler of the smallest
orifice size. The 90-second allowance
exists to reduce the number of
nuisance alarms caused by water flow
that can occur from pressure surges
in the water supply system. The delay
provides added assurance that the
water flow in the sprinkler piping is in
fact sustained flow from a sprinkler,
and not just the result in a change in
pressure. This delay can be created
within the flow switch itself, or it
can be accomplished with the use of
a retarding device such as a retard
chamber when using a
pressure switch.
The second part of this delay is
found in subsection 10.11.1. This
section requires that the actuation of
alarm notification appliances at the
protected premises occurs within 10
seconds after the activation of the
initiating device. This requirement
exists to ensure that the operation
of the notification appliances occurs
within a timely manner after a fire
has been detected. Between those two
requirements in subsections 17.13.2
and 10.11.1, NFPA 72 permits up to a
100-second delay between the initial
waterflow from a sprinkler and the
actuation of the notification appliances
within the building.
In addition to this allowance
intended to reduce the number of
nuisance alarms, allowances exist to
delay the actuation of notification
appliances for other initiating devices
with the use of a presignal feature or
positive alarm sequence, though both
of these require a detailed response
plan and approval from the authority
having jurisdiction.
The next time someone asks you a
question about the timing of sprinkler
waterflow and fire alarm notification,
remember that NFPA 72 permits
the delay in the actuation of fire alarm
notification appliances. This timing is
engineered into the operation of the
systems, and it exists to ensure that they
function as effectively as possible.
Jonathan Hart is technical lead, Fire Protection
Engineering, at NFPA. NFPA members and AHJs
can use the Technical Questions tab to post queries
on NFPA 25 at nfpa.org/25. To follow the progress
on the upcoming edition of the code, visit
nfpa.org/25next.
NFPA 13
Water-based fire
protection systems
The growing
importance of fire
suppression in
data centers
By Brian OConnor
R
emember the days
when dropping your
phone in the water or
spilling coffee over your
laptop meant the devices
data was lost forever? Those days are
gradually disappearing, fortunately-
the rise of cloud computing means your
information is backed up on servers
in vast data centers. And that growth
continues: recent reports project the
global data center market will grow by
$615 billion between now and 2026.
With all of this expanding infrastructure,
its important to protect these
buildings from fire and its associated
hazards. This is done through several
different fire and life safety design decisions,
most notably the installation
of sprinkler systems. NFPA technical
staff often receive questions regarding
whether sprinkler systems need to be
installed in these facilities.
Simply put, sprinkler systems are
essential to the protection of life
and property from the effects of fire.
However, some stakeholders in the
data center sector have expressed
concerns over the potential of an accidental
discharge of a sprinkler or water
damage from corroded piping in buildings
protected by sprinklers. These
concerns are amplified in data centers,
where the equipment can have high
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