NFPA Journal - September/October 2019 - 41

Supervision is a means of monitoring the status of a sprinkler system
and indicating certain abnormal
conditions that could impair the
system, such as a valve that is closed
when it should be open or open when
it should be closed. For electronically
supervised valves, the main concept
is to transmit a signal to a constantly
attended location when this condition
occurs. This informs the appropriate
personnel about both the condition and location so the appropriate
actions can be taken.
There are many different valves
in a sprinkler system, but not all of
them need to be supervised. NFPA 13
requires valves that control the flow
of water to any portion of the sprinkler system to be open and supervised.
Certain valves are already required to
be indicating-type valves, which means
you can tell if the valve is open or
closed just by looking at it. The problem with this is that sometimes these
valves are located in places that are
not constantly attended. This is why
NFPA 13 has requirements for making
sure the valves stay open and when
they are closed that someone who is
responsible for the system knows that
they are closed.
In lieu of electronic supervision,
NFPA 13 also permits valves to be
locked, sealed, and tagged to prevent
unauthorized closing. However, these
methods require additional vigilance.
For example, seals are required to
be checked every week to ensure the
seal has not been broken, and locks
are required to be checked monthly
to make sure they have not been
removed. Padlocks and chains are
especially useful in places where valves
are subject to tampering. In addition,
valves should be individually locked
and the distribution of keys should be
restricted to those directly responsible
for the system.
A device that electrically supervises the valve is arranged to monitor
the position of a component. These
will often be referred to as tamper
switches, because if someone is
tampering with the valve, the fire

alarm control panel will receive the
appropriate signal.
Although several means of valve
supervision are permitted by NFPA
13, a more sophisticated means
includes the use of what's known as
an automatic extinguishing system
supervisory device. The installation
of this type of device is addressed by
NFPA 72®, National Fire Alarm and
Signaling Code®. As noted above, the
most common type of device used
here is an electronically monitored
tamper switch that sounds an alarm
at a constantly attended location.
Other conditions that are required to
be supervised include the air pressure
in a dry pipe or preaction system and
the water temperature in a circulating
closed loop system, because if either
of those fail it could lead to ice blocks
forming within pipes, either breaking
them or blocking water from reaching
the sprinkler.
Just because the supervisory device
indicates certain components are in
the correct position doesn't mean your
system is in perfect operating condition. Frequent inspection, testing,
and maintenance in accordance with
NFPA 25, Standard for the Inspection,
Testing, and Maintenance of WaterBased Fire Protection Systems, is still
required to ensure all of the system
components continue to function
as intended. And to further reduce
the chances of the valves being inadvertently left closed, NFPA 25 also
requires the implementation of a
robust impairment program. This
includes a specific focus on ensuring all valves are open following any
system repairs or updates. With proper
installation, including selection of the
best option to supervise critical system
valves and components, coupled with
an ongoing inspection, testing, and
maintenance program, an automatic
sprinkler system will greatly reduce
your risk of loss of life and property
from fires.
Brian O'Connor is a fire protection engineer at
NFPA. NFPA members and AHJs can use the Technical Questions tab to post queries on NFPA 13 at
nfpa.org/13.

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NFPA Journal - September/October 2019

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