Understanding the Benefit
FM Approved Water Mist Systems
The Hazard
Beyond the typical fire protection scenarios that can be addressed with conventional
sprinkler systems, there are many situations or environments that call for special fire
protection. In these situations, the potential result of a fire could be catastrophic to
property and life, where even a small fire could have devastating consequences.
For instance, special situations or operations may include industrial turbine enclosures,
semiconductor clean rooms and wet benches, food processing lines, industrial oil
cookers, power plant turbines, raised floor spaces in data centers, and continuous
wood product processing.
One of a series of publications
designed to illustrate the importance
of product testing and certification and
the benefits of using products that have
been tested and certified by reputable
organizations such as FM Approvals.
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pproval Standard 5560, Approval
A
Standard for Water Mist Systems
ANSI/FM Approvals 5560, American
National Standard for Water Mist
Systems
Approval Standard 5580, Approval
Standard for Hybrid (Water and Inert Gas) Fire Extinguishing Systems
Benefits of FM Approval:
T he most comprehensive water mist
standard in the world
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Renowned authority in property loss
prevention, including water mist and sprinkler technology
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Approval Standard incorporate
decades of intensive research, actual
loss experience, and field engineering
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Application-specific testing ensures
effectiveness when installed according to guidelines
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In the ultra-clean world of semiconductor manufacturing, for example – where the
air is 10,000 times cleaner than the average office – cleanup from even a relatively
minor fire can take weeks, resulting in large financial losses, lost market share and
lost orders. It’s estimated that downtime in this industry costs approximately
US$1 million per hour.
In this and other special applications, particularly environments that are sensitive to
water damage, water mist fire suppression systems have long been used. Water mist
has many unique properties that make it an excellent suppression and extinguishing
agent for many special applications. In enclosed spaces, the atomized water droplets
are quickly drawn to the base of the fire along with room air. The water instantly
flashes to steam replacing the oxygen needed for combustion.
This effective extinguishing action, along with an overall cooling and air scrubbing
effects, make water mist highly effective when delivered correctly. Unlike most flooding agents water mist works in areas where a door or vent has been left open and does
not pose a health risk to occupants or firefighters, and it is environmentally benign.
Testing Required for FM Approval
All FM Approved water mist fire protection systems have undergone extensive
testing in accordance with the requirements of Standard 5560, Approval Standard
for Water Mist Systems. This standard provides the most comprehensive single
source of water-mist test requirements in the world for land-based applications.
Successes:
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According to a report in the journal
Professional Mariner, a water mist
system put out a fire in the main
machinery spaces aboard a high
speed ferry operating between
Helsinki, Finland, and Tallinn, Estonia,
in August 2000. The fire resulted from
a turbo charger failure. The ferry
owners noted that the water mist
system did the job it was designed
for: to “kill the fire, not fight it.”
Approval Standard 5560 provides test requirements for specific occupancies and
applications that FM Approvals has tested and verified. These specific applications
and occupancies are covered in appendices to the standard, including:
n Machinery spaces and special hazard machinery spaces with volumes
up to or exceeding 9175 ft3 (260 m3);
n Combustion turbines enclosures;
n Industrial oil cookers;
n Light-hazard occupancies such as nonstorage and nonmanufacturing areas,
residential, offices, meeting rooms, hotels, museums, restaurant seating areas,
institutions and schools;
n Wet benches and similar processing equipment;
n Local application occupancies;
n Computer room subfloors; and
n Continuous wood board presses
Since each water mist system is unique in its operation and design, component testing
of the water mist system is done on a case-by-case basis. The 296-page Approval
Standard 5560 includes performance requirements for almost every type of watermist system component.
Water mist systems can be categorized as single fluid or twin fluid. A single-fluid
system uses a single pipe network to supply water mist nozzles. The twin-fluid
system uses two independent pipe networks to supply water and compressed air or
inert gas separately to water mist nozzles. Extinguishing systems using compressed
air as their atomizing medium shall be considered a twin fluid water mist system and
be evaluated according to Approval Standard 5560.
Fire extinguishing systems that use an inert gas and water, where both components
are critical factors in fire control, suppression or extinguishment, are known as hybrid
systems. The gases used in hybrid fire extinguishing systems may include helium,
neon, argon, nitrogen, carbon dioxide or various gas blends.
Hybrid fire extinguishing systems are evaluated in accordance with Approval Standard 5580, Hybrid (Water and Inert Gas) Fire Extinguishing Systems. Since each
hybrid system is unique in its operation and design, the component testing of the
system shall be performed on a case-by-case basis. Upon request for a program, and
appropriate system documentation, FM Approvals will prepare a customized evaluation program for the specific hybrid system.
But What About…
Cost? It is important to understand the product manufacturer’s pricing structure.
It may appear that the cost of a tested and certified FM Approved water mist system is
more than that of a comparable, non-certified system. Reputable testing and certification
organizations such as FM Approvals will run tests and perform facility audits, which
may, in fact, increase the cost of the product compared to similar, non-certified products,
but not always.
The best place to start any pricing comparison is the manufacturer’s website. The
Approval Guide, an online resource of FM Approvals, provides links to the websites of
most manufacturers that produce FM Approved products along with the listing for the
products. That link will often go to a pricing sheet, or at least to a representative who can
explain the actual cost that a manufacturer is charging his customers.
Understanding the Benefits
This is one of a series of publications to
help you understand how FM Approved
products can help prevent losses in your
facility. For more information on how
to obtain FM Approval of your product,
contact the FM Approvals representative below:
Richard Dunne
Tel: +1 (1)401 567 0590
Fax: +1 (1)401 567 0599
richard.dunne@fmapprovals.com
FM Approvals LLC (FM Approvals) is making
this brochure available for informational purposes
only, in support of the relationship between
FM Approvals and its customers. This information does not constitute an Approvals agreement,
standard or certification. No liability is assumed
by or through the use of any information.
P10227 © FM Approvals, December 2010
All rights reserved. www.fmapprovals.com
Installation guidelines? FM Approved water mist fire control and/or extinguishing
systems are complemented by the guidelines for installation, use and maintenance
provided by FM Global Loss Prevention Data Sheets. Some of the Data Sheets that
address water mist systems include: 4-2 Water Mist Systems, 7-79 Fire Protection for
Combustion Turbine Installations, 7-7 Semiconductor Fabrication Facilities, and others
in the 7 series.
Local code and jurisdictional requirements? FM Approvals incorporates jurisdictional
and code requirements into its testing Approval Standards as well as providing rigorous
property loss prevention criteria. All users of FM Approved products can rely on these
products to be acceptable by local jurisdictions, as well as provide the loss prevention
solutions prescribed by FM Global.