The first automatic fire sprinklers were commercially marketed
in the US in 1874. There have been minor advances in the basic
technology since that time, despite the ever increasingly
complex governing codes and standards that result from evolving
occupancies, fires, new research and ever increasing public
awareness.
Properly designed automatic sprinkler systems control fire,
reduce property damage, business interruption and save lives.
However, this requires routine inspection, maintenance and
testing as well as continual reassessment to assure success.
Concerns relating to the major components are discussed below.
Consult NFPA 25 “Inspection, Testing and Maintenance of Water-
Based Fire Protection Systems” or other appropriate
codes/standards for detailed requirements.
Sprinkler Heads
Automatic sprinklers discharge water through an orifice when the
heat from a fire fuses a thermal element. Once fused, the water
impacts a deflector and is dispersed in circular pattern.
Automatic sprinkler systems are designed to operate many heads
simultaneously. In order to control or suppress a fire the heads
must operate without delay.
Look for damaged deflectors, painted thermal elements, leakage,
corrosion, physical obstruction, or older (obsolete) sprinklers.
Test or replace heads if their reliability is questionable.
Control Valves
Sprinkler control valves are provided for the purpose of shutting
off water to the sprinkler system in the event of accidental leak
or for system maintenance. Valves that are inadvertently left
closed can impair a sprinkler system. Inoperable valves can
cause significant water damage if they cannot be quickly closed.
Periodically inspect sprinkler control valves to insure that
they are in the open position. Functionally test them to ensure
that they will operate. Consider locking or sealing valves in
the open position to deter against unauthorized tampering,
particularly if they are accessible to the general public.
Develop an impairment management program to ensure that any valve
closures are monitored, that the number of impaired systems is
minimized, that protection is restored promptly and that proper
precautions are taken to prevent against fire when systems are
impaired.
Dry pipe, preaction and deluge valves are designed to introduce
water into the piping network after being tripped. Dry pipe
valves are designed to operate when an automatic sprinkler head
fuses and the system’s air pressure drops. Deluge valves are
used with open heads and operate when signaled by a detection
system. Preaction valves, and related designs, employ both
methods of activation.
Periodically test all detection systems, and devices such as
accelerators and exhausters that effect riser control valve
actuation. Routinely trip test and maintain all dry pipe,
deluge, and preaction valves to ensure their proper operation.
Piping
Obstructed piping results in an impaired sprinkler system.
Obstructions occur in cast-iron pipe as a result of
tuburculation. Dry systems have the worst track record with
corrosion, and galvanized piping is commonly installed to
compensate. Obstruction can occur when from foreign materials,
or living organisms, are introduced via the water supply (e.g.
rocks, sediment, clams, microbiological induced corrosion (MIC),
etc.). Sudden failure can result in deteriorated pipe when
systems are exposed to high flow and pressure during fire
conditions. Galvanized pipe corrodes quickly at elevated
temperature.
Flow 2 in. drains and inspectors test connections to ensure that
system piping remains unobstructed. Dry pipe systems that use
cast-iron pipe should have flushing investigations performed
routinely. Periodically inspect freezer systems for ice plugs.
Treat and inspect systems that are prone to
obstruction/deterioration from MIC, Asian clams or zebra mussels.
Thoroughly investigate any obstructions promptly and determine
the cause. This will likely require disassembly and/or flushing
of all piping. Flush the system by flowing water through the
largest pipes first so as to not introduce large amounts of
obstructing material into the smaller pipes. Adequate velocity
is essential.
In winter it is critical to maintain adequate building heat to
prevent freezing. Check dry systems for proper piping pitch and
drain drum drips routinely. Inspect dry pipe valve riser houses
to ensure adequate heating.
For older and suspect systems that have leaked or failed, conduct
a hydrostatic pressure test to determine suitability for
continued use. If testing cannot be performed, replace the
system.
Water Supply
The water supply consists of a source and a means of delivering
adequate flow and pressure to the automatic sprinkler system.
Sources include tanks, wells, lakes, ponds or rivers. Flow and
pressure is supplied by gravity, pumps and in some cases pressure
tanks. Large public water systems utilize a redundant
combination of gravity and pumping and are generally reliable.
However, uncontrollable changes may impact system adequacy.
Sources, pumps, underground piping and valves are subject to
impairments that could render an automatic sprinkler system
ineffective.
Perform flow testing in the vicinity of the automatic sprinkler
system to assure that the design remains adequate. Inspect and
maintain control valves as outlined above. Flow test isolated
underground main legs to ensure that there are no obstructions.
Test start fire pumps frequently to ensure that they will start
automatically. Flow test fire pumps to assure their continued
performance. In winter, routinely check heating systems in tanks
and fire pump rooms to prevent against freezing. Treat raw water
sources for clams, mussels and excess vegetation, and routinely
clean suction intakes
Reevaluation
Continually reevaluate sprinkler system adequacy to ensure the
systems remain capable of protecting property, reducing business
interruption and saving lives. Reevaluate changes in occupancy,
combustible load, storage configuration, products and processes.
Apply the most modern codes and standards, and reassess the water
supply for comparison to each sprinkler system’s calculated
demand.
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