Fighting Fire in Sprinklered Buildings

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This brochure is made available for informational purposes only in support of the insurance relationship between FM Global and its clients. This information does not change or supplement policy terms or conditions. The liability of FM Global is limited to that contained in its insurance policies.

A fire ignites in a sprinklered build-ing. Automatic sprinklers detect it, sound an alarm and discharge water to control or suppress it until fire-fighters arrive with hose lines. The fire should not survive such an effec-tive attack, but the fact remains—fire can destroy a sprinklered building!

What Can Go Wrong?Did you know that firefighters can unintentionally make a fire worse? Of course, they don’t mean to. But sometimes—despite expert fire-fighting skills—they make incorrect assumptions.

Closing Sprinkler ValvesFirefighters may prematurely shut down the automatic sprinkler system at the fire scene for fear water will damage valuable equipment or smoke will obscure their vision. Unfortunately, too many major fires have spread faster or reignited after the sprinkler system was shut down too early.

No one wants to lose a building. But, which is worse—a building in ashes or a building with some water and smoke damage?

Turning Off Electric PowerOn occasion, firefighters cut electric power when they first arrive at the fire scene, assuming the facility’s electric fire pump will not be affected. If the fire pump is on this circuit, however, a utility shutdown could cut off the water supply needed to feed the

sprinkler system. Without water, a small fire can burn out of control very quickly.

Advance Preparation Is KeyFirefighters also need to know about a facility’s pumping capabilities and limitations before fire strikes.

When fighting fire in sprinklered buildings, firefighters and automatic sprinklers are partners, each playing a separate, yet complementary, role. But, to operate effectively with the sprinkler system, firefighters must understand what it is designed to do and take advantage of its capa-bilities. They also must know about pre-existing conditions that can destroy sprinklered buildings. Errors at a fire scene can result from sprinkler system impairments and inadequate protection:

System Impairments■■ Shut down. Facility personnel

create a severe fire hazard when they shut down the automatic sprinkler system for repairs

(or for any other reason) and fail to reactivate it promptly after ward. Fire severity can be re-duced if the protection system is restored and operating before a fire ignites.

■■ Inadequate maintenance, testing or infrequent inspections. Ultimately, any of these can al-low an impairment to go unde-tected and destroy a system’s ability to respond to a fire.

■■ Arson. If an intruder shuts down the system and ignites a fire, the property is unprotected by sprinklers.

Inadequate Protection■■ Improper system installations.

If the sprinkler system was not installed according to recognized guidelines, it likely will not operate properly.

■■ Poor system design. If the system is not well-designed or is not designed for the area or occupan-cy it is expected to protect, it is likely protection will be insufficient.

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■■ Improperly protected construc-tion sites. Fire protection should be installed at the site early in the construction phase. If it is not up-graded as construction continues, protection is not guaranteed.

■■ Changes to storage arrange-ments. If a facility’s storage vol-ume has increased, storage height has grown or the items stored have changed since the sprinkler system was installed, the sprin-kler system needs to be evaluated for possible upgrades. Protection may no longer be adequate.

■■ Construction renovations. Any renovation made without regard to how the new construction af-fects the sprinkler system could overtax the system.

■■ Poor public water supplies. Occasionally, firefighters have watched buildings burn. If they have no guarantee that the vol-ume of water they need to stop the fire will be available, they may be forced to protect sur-rounding exposures rather than fight the fire. In some areas, dis-tribution main lines leak because of age or lack of maintenance. Sometimes, a fire service’s only option is to ask the water au-thority to boost the supply—an action that can take hours, if it’s even possible.

Common Errors Involving Sprinklered FacilitiesFM Global loss experience shows that certain errors in sprinklered buildings are common:■■ Competing with sprinklers for

water. When the sprinkler system and hose demand use the same water supply, the sprinklers may not operate effectively due to lack of water supply or volume needed.

■■ Shutting off the sprinkler system. Again, unchecked fire spread is far worse than decreased visibil-ity due to smoke. It is important to shut down sprinklers only when all pockets of concealed fire have been extinguished and all areas checked for fire spread extension. Even then, charged hose lines should be in the area during cleanup operations.

■■ Allowing smoke and heat vents to open prematurely. Opening the vents before sprinklers controlling the fire have operated may fan flames with outside air,

creating greater fuel consump-tion, increased water demand and a more fully developed fire. Vent-ing may prevent sprinklers from controlling or suppressing the fire. FM Global does not recom-mend installing automatic vents in sprinklered buildings.

Why Sprinklered Buildings Should Not Be VentedOriginally used in unsprinklered buildings, roof vents are usually designed to open automatically dur-ing a fire and vent smoke and hot gas out of the building. Vents can help firefighters by increasing visibility, but only if venting occurs at the right time during the firefighting operation.

Although venting has value in unsprinklered buildings, its purpose in sprinklered buildings is question-able at best. While conclusive data is unavailable to support the notion that automatic vents can benefit a sprin-klered building, studies have shown

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that vents, in some cases, can have a negative effect. Inside a building protected by suppression-mode sprin-klers, for example, a fire that starts directly under an automatic vent can cause it to open before the sprinklers, delaying sprinkler operation. Because the key to successful fire suppression is rapid discharge while the fire is in its earliest stages, this delay can mean the difference between a small fire and a catastrophe.

A Few Tips for Solving This Problem:■■ In general, FM Global does not

recommend that smoke and heat vents be installed in all buildings, but there are special situations.

■■ In new sprinklered buildings, where vents are required by local code, install vents for manual, not automatic, operation, if al-lowed by code officials. This will keep vents closed until firefight-ers arrive and give sprinklers a better chance of controlling the fire. Firefighters then can decide when venting is needed.

■■ In sprinklered buildings with automatic pop-up vents, install a fusible link on the vents with a substantially higher temperature rating than sprinklers. Such links prevent premature venting that would delay initial sprinkler op-eration. FM Approved “fire door fusible links” can be used for this application and are available in ratings up to 520o F (271o C).

■■ Sprinklers then will operate first and cool the fire. The cooler

temperature at the ceiling should prevent the vents from opening prematurely. Or, another option is to replace the fusible link on the vents with a nonfusing blank to keep the vent from opening. Adjusting the operating tem-perature is not an option with thermoplastic drop-out vents.

■■ Use alternatives to automatic vents such as windows, monitors, doors, or gravity or mechanical manual exhaust systems. Fire-fighters also can cut holes in metal or wood roofs and use smoke ejectors. Such options are effective in most storage facilities and in buildings without windows.

■■ Vents installed with noncombus-tible draft curtains are accept-able in large areas where vents are required by code and full height partitions are not practical. However, draft curtains should be centered over a wide aisle to prevent hampering of sprinkler operation. The curtains channel hot air and gas to a limited area at the ceiling, helping the vents to release the gas outside.

■■ Vents also are acceptable in certain sprinklered buildings that contain localized hazards such as flammable liquid operations or other hazardous material that have a high heat-release rate, but again, are effective only if they operate at the right time during a fire. Use noncombustible, fire-resistive partitions to separate these areas from the rest of the building.

■■ In unsprinklered buildings, venting can remove smoke to aid manual firefighting and, possibly, limit heat buildup. Vents are not a substitute for automatic sprin-kler protection in any building with combustible construction or contents.

For more information, see FM Global Property Loss Prevention Data Sheet 1-10, Smoke/Heat Venting in Sprinklered Buildings.

Eliminating the ProblemPrefire planning is essential. It gives firefighters the opportunity to visit the facility before an emergency occurs. Common firefighting errors can be prevented by examining the following elements at the site:■■ Construction of the facility■■ Number of people occupying

the facility■■ Operations involved■■ Contents of the building—stor-

age, manufacturing, hazardous material (plastics, flammable liquid, etc.)

■■ Type of sprinkler system and extent of protection

■■ Water supply to sprinklers, including source and type of supply—gravity tanks, private pumps, reservoirs or public mains—and volume and pressure of the supply

■■ Location of all sprinkler control valves, how they operate (direc-tion of opening), and what each valve controls

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■■ Location and function of all fire service connections to sprinkler systems, which area each con-nection serves, and how pumpers and hose lines will be set up to feed the sprinkler connections

■■ Which responding fire apparatus will charge fire service connec-tions

■■ Location of alternate water sup-plies in case the water supply is depleted by damaged connec-tions or hose-line demand

When Arriving at the Fire SceneWell-trained firefighters know it is best to work with facility personnel to extinguish the fire. Here are a few tasks where personnel can provide valuable assistance:■■ Size up the location and extent of

the fire. The facility’s emergency response team (ERT) often can direct firefighters to the fire’s exact location.

■■ Check sprinkler control valves to confirm they are open. Whether firefighters or the ERT handle this should be decided during a prefire planning site visit. To check the valves, it’s helpful to follow a step-by-step routine:

1. Send someone with a two-way radio to the sprinkler system’s main control valve. The valve should be unlocked.

2. Physically try the valve to ensure it is open.

3. Remain at the valve to close it upon orders from the incident commander.

4. Check interior valves when safe to do so.

5. If private pumps supply the sprinklers, send another person to the pump house to ensure the pumps are running and all suction and discharge valves are open.

6. Station someone at each valve that controls operating sprinklers. This will prevent an unauthorized person from closing any valve. The incident commander must be sure sprinklers continue to operate until the valve is ordered closed after the fire is completely extinguished and the reignition potential is eliminated.

■■ Reinforce the water supply to sprinklers by using fire service connections:

1. Hook up a minimum of one pumper supply line, charged to a pressure of 150 psi (1,035 kPa), to the fire service connection.

2. Hook up additional lines as needed and increase the wa-ter pressure accordingly. The pumper takes water from

another water source (usually

a public hydrant, tanker or stand-ing body of water) and pumps it into the sprinkler system. This boosts the water volume and pressure to sprinklers. Sprinklers can deliver water more effec-tively than hose streams.

■■ Lay handlines after making sure the fire service connections have been utilized. Although larger lines are sometimes used, 1 1/2-in. (38-mm) or 1 3/4-in. (44-mm) lines usually are adequate for interior attack. Using these lines will prevent fire spread and extinguish any remaining fire. Lay large hose lines (2 1/2-in. [64-mm]) in case the fire de-velops beyond the point where sprinklers can control it. This might happen if highly combus-tible material is present or the sprinkler discharge is obstructed.

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■■ Take water from sources that will not rob sprinklers of an adequate water supply. Supply pumpers by:

1. Connecting to large mains that have been flow-tested and proven adequate to supply both sprinklers and hose streams.

2. Using water mains other than those needed to supply sprinklers.

3. Drafting from static sources, such as a pond or river.

■■ Do not allow hose lines to deplete the water supply to the sprinklers. Otherwise, the fire will spread, fusing additional sprinklers and further depleting the water supply. This increases the fire damage and makes it difficult for firefighters to control the fire.

SalvageMembers of the ERT can assist with salvage under the direction of the incident commander. The ERT can close fire doors, relocate stock and spread salvage covers over items that might be affected by operating sprinklers or hose lines. After the fire is extinguished and the sprinklers or-dered closed, firefighters can conduct a routine overhaul. At this point, use FM Global’s Red Tag Permit System Wall Hanger (P7427) until the sprin-kler system is restored to full opera-tion. This requires attaching tags to closed valves to alert everyone that they are closed temporarily.

FM Global Can Provide Site-Specific AssistanceFM Global engineers can assist cli-ents and firefighters in solving many of the problems described in this brochure. For example, our engineers work with the local fire service and facility managers to identify on-site backup water supplies. Additionally, they can provide on-site training ses-sions for firefighters.

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Print Resources FM Global’s Resource Catalog for Public Fire Service Professionals (P9402) de-scribes the various services FM Global provides free or at low cost to firefight-ers throughout the world. ■ Pocket Guide to Arson and Fire

Investigation (P7923) explains gen-eral fire investigation techniques, the various steps in detecting ar-son fire, and how to follow through with prosecution. An easy-to-use flow chart and an ignition sources chart also are included.

■ Pocket Guide to Automatic Sprinklers (P8807) describes the fundamentals of automatic sprinkler systems, from types of sprinklers and their temperature ratings to alarms and sprinkler control valves.

■ Pocket Guide to Prefire Planning (P9809) explains how firefighters and property management can arrange an ongoing partnership—one that is well worth the effort for all involved. A detailed check-list spells out items firefighters should review with facility person-nel as they tour the property during the prefire planning visit.

■ Reducing the Arson Threat (P7721) describes the 12 steps any busi-ness should take to stop the arson threat. Facilities targeted by arsonists or facilities that have already experienced one or more arson fires should follow additional guidelines cited in this publication.

CD-ROM ■ Fighting Fire in Sprinklered Build-

ings (P9923CD) is an effective CD-ROM that includes: • Information on:

■› How sprinkler systems are designed

■› What causes sprinklered buildings to burn

■› How fire services can support automatic sprinkler systems

■› The importance of prefire planning

• Video clips to expand the understanding of concepts

• Instructor’s manual • Student guide

ERC Loss ControlFM Global fire service training material, resources and seminars are designed to help you understand a wide range of property hazards. When it comes to training emergency response person-nel, however, no tool or organization is more effective than FM Global Emer-gency Response Consultants. Located in Rome, Ga., USA, this member of the FM Global Group specializes in the training of industrial fire brigades, hazardous material emergency rsponse teams, technical rescue teams, inspec-tion and maintenance personnel,and those responsible for organizing, managing or directing emergency-re-sponse activities. Specifically, programs provide training in the following areas: ■ Firefighting at all levels (includ-

ing interior structural, advanced exterior and incipient)

■ Hazardous material emergency response at all levels (awareness level through the specialist level)

■ Technical rescue at all levels (awareness level through techni-cian level with special focus on confined-space and high-angle rescue operations)

■ Incident command/incipient management

Fire protection systems/equipment maintenance and inspection programs are customized to provide realistic training experiences that closely match your specific needs, and are designed to help you comply with applicable laws, regulations and standards. Examples include Occupational Safety and Health Administration (OSHA) and Environ-mental Protection Agency (EPA) regulations, National Fire Protection Association (NFPA) stan-dards, and many other regulatory and voluntary consensus requirements that affect industrial emergency response operations.

Such training is presented by highly skilled instructors with extensive fire service experience, and delivered on site at FM Global Emergency Response Consultants’ state-of-the-art training center or at any location you specify worldwide.

For more information on Emergency Response Consultants and its various training programs, call +1 (1)706 291 1222 or visit fmglobalerc.com

Other Fire Service Resources

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