FROZEN SPRINKLER
PIPES: WHEN THEY BURST THEY CAUSE SIGNIFICANT DAMAGE
If your building association has experienced water
damage because of frozen sprinkler pipes, this is the first indication that you
need additional freeze protection to prevent this from happening again. The
following points will help reduce the risk of frozen sprinkler pipes.
·
Maintain heat in all buildings and units
·
Require an annual service and maintenance
contract on all fire sprinkler systems
·
Provide additional insulation for pipes in
unheated areas such as attics
·
Install water flow alarms to alert occupants
that water is flowing in the sprinkler system
·
Install freeze alarms to warn of potential
freezing conditions before the pipes freeze
Impact of
Building Codes
There are approximately 3000 residential fire deaths
each year. Statistics compiled by the National Fire Protection Association
(NFPA) conclude that the chance of dying in a home fire decreases by 80% when
residential sprinklers are present.
Many municipalities already require sprinkler systems in
new one and two family homes, townhomes and condominiums. The 2009 edition of
the International Residential Code (IRC) requires sprinkler systems in these
homes. As more municipalities adopt this edition of the building code, the
number of systems will increase and so will the potential for water damage from
burst sprinkler pipes.
Building and fire codes are regulatory requirements that
establish minimum standards for construction of safe and habitable buildings.
The code requirements for residential sprinkler systems seeks to minimize fire
deaths by controlling heat, smoke and flames so occupants have time to escape.
There is minimal emphasis on preventing frozen pipes and water damage.
While one cannot equate the value of a human life to
water damage, you cannot overlook the extensive damage caused by accidental
discharges from faulty systems and burst piping, which is often more extensive
than fire damage.
When Pipes Freeze,
Water Expands up to 10 Percent in Volume
When water freezes at a temperature of 32ºF or below it
expands up to 10 percent in volume. Sprinkler pipes tend to freeze before other
water pipes because the water is not moving.
Most sprinkler systems are wet systems that contain
water all the time. Sprinkler systems include check valves and backflow
preventers to separate the sprinkler water from the potable water supply. These
valves create a closed system in which the pressure cannot escape.
When water freezes inside a sprinkler pipe, it creates
an obstruction that can render the sprinkler system useless in the event of a
fire. As the ice expands, it increases the internal water pressure in the pipe
and causes the pipe to burst. Interestingly, the burst is often in a section of
pipe that did not actually freeze.
Alternatively, the expanding ice can cause a pipe,
fitting or sprinkler head to crack but the ice will block the flow of water
while it is solid. In this case, the actual water damage will not be apparent
until the ice melts and water flows out of the burst section.
Where the pipe bursts and the time it takes to shut off
the water will influence the amount of water damage to the unit. Most
residential sprinkler systems use 1” pipe, which, at a typical street pressure
of 70 pounds per square inch (psi), will flow about 30 gallons per minute
(gpm). In as little as fifteen minutes, almost 500 gallons of water will
saturate the unit and adjoining units.
Preventing Frozen
Pipes
The best way to protect a residential fire sprinkler
system from freezing is to provide sufficient insulation and maintain adequate
heat during the winter months. The type and amount of insulation must be
suitable for the coldest local temperatures. During construction, sprinkler
systems are usually in place before the insulation so there is a possibility
that the installer could place the insulation on the wrong side of the pipes
thus exposing them to freezing temperatures.
Insulation helps block the flow heat or cold from one
space to the next. Most sprinkler pipes are within the walls or ceilings of a
home. Cold air can enter these concealed spaces through small gaps in the
exterior sheathing and insulation and find its way into pipe chases and soffits
that focus the air directly onto the sprinkler piping and accelerate freezing.
It is important to verify that sprinkler piping in walls
is located between the heated interior space and the insulation. In attics,
piping should be as close to the ceiling as possible with insulation placed
over the pipe in the shape of a tent to trap heat around the sprinkler pipe.
When sprinklers are required in unheated spaces such as
attics or crawl spaces, the use of a dry system, or special dry sprinkler heads
are required.
A dry system has no water in the piping. The pipes
contain air or nitrogen under pressure and when a sprinkler head activates, the
pressurized gas escapes and allows water to flow.
Dry sprinkler heads have a short, length of pipe with a
seal mechanism installed to prevent water from entering the unheated space
until the sprinkler head activates. The sprinkler piping is in a heated space
and the sprinkler heads extend into the unheated space.
As of August 2010, the NFPA has banned the use of
antifreeze in all new sprinkler systems. For existing systems, NFPA recommends
draining the antifreeze and filling the pipes with water then providing
additional insulation along with other measures to prevent the pipes from
freezing.
If you have sprinkler systems that contain antifreeze,
contact your sprinkler contractor immediately to drain the antifreeze and
refill it with water then verify that there is sufficient insulation, installed
correctly, to prevent the pipes from freezing. The contractor should also
install any additional protection needed to prevent the pipes from freezing.