Why Sprinkler Systems
FIRE PROTECTION
For more than one hundred years, sprinklers have proven their effectiveness in fire suppression…. So why are fully sprinklered buildings burning down?
(Photos by author.)
AUTOMATIC SPRINKLERS have proven themselves to be the most reliable form of fixed fire protection over the past 100 years. Statistics compiled by various organizations, most notably the National Fire Protection Association, have shown that fires occurring in buildings protected by automatic sprinkler systems are controlled or extinguished by the sprinklers 96 out of 100 times. In fact, the success rate is probably even higher than reported because there are numerous small fires in industry every day that are controlled or extinguished by automatic sprinklers but are not reported to the public authorities and therefore are not reflected in the published statistics.
In some areas, such as Australia and New Zealand, where inspection and reporting requirements are much more stringent, the success rate of automatic sprinklers has been reported to be as high as 99 76 percent. Closer to home, the United States Department of Energy reports a 99.4 percent rate of successful fire control for fires occurring in their sprinklered facilities since 1952.
As a result of this most favorable performance record, the fire protection community has placed a great deal of confidence in the ability of automatic sprinklers to control a fire. This exceptional performance record allows us to buy fire insurance for a sprinklered building at a much reduced rate. It also permits us to make trade-offs (valid or not) in newly constructed and renovated buildings that often reduce the overall cost of the building. For example, if a building is equipped with automatic sprinklers, the building code may permit larger, undivided fire areas, or the fire resistance rating of certain building members may be reduced.
Automatic sprinklers have indeed proven themselves as the most effective type of fixed fire protection system for most applications. Why is it, then, that the automatic sprinkler’s promise of quick, effective fire control is being broken more and more often? Why is it that fully sprinklered buildings are burning down? In short, why do sprinkler systems fail? Let’s look at some recent examples that illustrate the reasons.
INCOMPLETE SPRINKLER PROTECTION
While there are few black-and-white rules in the fire protection field, one of them has to do with where automatic sprinklers should be installed. It seems like a very elementary concept that should not have to be spelled out, but automatic sprinklers cannot be expected to control a fire if they are not installed in all areas where they are needed. This need should be based on a technical analysis of the area and not on a political document such as a building code, which very often fails to require sprinklers based on the area of the building, the date of construction, or some equally invalid criteria. The Beverly Hills Supper Club, in which 165 people died in 1977, was not required to be sprinklered even after a fire severely damaged the establishment in 1970.
Very simply, automatic sprinklers are needed anywhere there is a combustible occupancy and anywhere combustible building materials are used. Strict adherence to this rule could have prevented many well-known fire disasters.
A perfect example of providing only partial or incomplete sprinkler protection was the MGM Grand Hotel fire in 1980. This fire, which killed 85 people and injured over 600 others, is often used as an example of the need to install automatic sprinklers in high-rise hotels. The fact that sprinklers were absent from the area of origin and in the casino area contributed to the rapid flame spread through the ground floor.
What most people often fail to realize is that the MGM Grand Hotel was provided with a partial sprinkler system. Automatic sprinklers were provided in several areas surrounding the casino, and the sprinklers in these areas were very effective in halting the spread of the fire. The NFPA investigative report on the fire stated, “There was a distinct separation between damaged and undamaged areas that corresponded with the line between sprinklered and unsprinklered areas. There was no evidence of flame damage in the sprinklered [areas]…it was evident that the fire spread was stopped where sprinkler protection began.”
In many industrial facilities, sprinklers are routinely omitted in renovated areas, “temporary” structures such its office modules or office trailers in a manufacturing area, beneath mezzanines, and other similar areas. Hi esc unsprinklered areas are the Achilles’ heel of a sprinklered building. A fire originating in one of these unsprinklered areas can rapidly spread and cause significant damage to or even burn down a building that the owner may think of as “protected” by automatic sprinklers.
During prefire planning surveys, fire officers should note the presence of unsprinklered areas within an otherwise sprinklered building. They should realize that if a fire originates in one of these areas, they will be faced with a more serious situation on arrival than would normally be expected from a “sprinklered” building.
IMPAIRED SPRINKLER SYSTEMS
The second major reason that sprinklers fail to control a fire is because the sprinklers are impaired or turned off at the time of the fire. On July 15, 1978, a large portion of the Phoenix Glass Company in Monaca, Pennsylvania burned to the ground. Although the management of the facility invested heavily in fixed fire protection systems, disaster resulted because they were not in service at the time of the fire.
A sprinkler contractor was hired to replace two obsolete dry-pipe valves. During the course of the work, the contractor requested that the incoming city water supply to the plant be shut down. Plant personnel complied with the request, resulting in an impairment of all 14 sprinkler systems in the facility.
During the course of the work, a fire was discovered by an employee. It spread unchecked because the sprinkler systems were shut off. By the time the main control valve could be reopened, the fire had grown so large that the sprinklers were overpowered and were ineffective in controlling the fire. The fire w?as not stopped until it reached a substantial masonry fire barrier where the public fire department could make a stand.
The impairment of automatic sprinkler systems for maintenance and repair occurs on a regular basis in most industrial facilities. Unfortunately, most people vastly underestimate the vulnerability of the facility at this time. When the sprinklers are impaired, the facility is unprotected, and emergency measures must be taken to prevent a fire and to expedite system repairs.
Fire departments should require that they be notified any time that automatic sprinkler systems are shut down for repairs or maintenance. When notification of an impaired sprinkler system is received, it should merit more than a simple note on a station chalkboard that may or may not be read by other personnel.
A building w ith the sprinklers shut off poses an entirely different problem than the sprinklered version of the same building. A new strategy must be developed for the building until the sprinklers are returned to service, and everyone must be aware of the new plans. Someone should also be assigned to follow-up to see that the sprinklers are restored at the conclusion of the required work.
INADEQUATE MAINTENANCE
The sprinklers do not have to be turned off in order for them to be impaired. Inadequate maintenance of the sprinkler systems can also result in impaired protection. On April 16, 1984, a plywood manufacturing plant in Nacogdoches, Texas burned to the ground, resulting in an estimated loss of S32.5 million.
The plant, built in 1970, was constructed with plywood walls and roof decking supported on wood trusses and columns. Three large bays formed a single fire area of 236,000 square feet.
The facility was protected by twelve dry-pipe sprinkler systems supplied from a 10-inch fire main which looped the plant and was supplied from both 12-inch and 8-inch public water mains. Two additional dry-pipe systems fed 30 hose stations throughout the facility.
At about noon, workers were attempting to repair a motor on one of the two hot glue presses in the plant. A broken bracket was to be repaired using an arc welder. The operation was to take place on top of the press near the roof. Prior to starting the hot work operation, the press was shut down, all plywood was removed from it, the area was wet down with a small hose, and a fire watch was established.
The repair work started and continued until about 12:25 p.m., at which time the welder discovered a fire burning just above him on a catwalk. The fire watch on the floor was unable to control the fire, and it quickly spread through the truss work, feeding on dust accumulations.
An employee saw the fire, turned in the alarm, and then attempted to use a 1 1/2-inch hoseline to attack the fire. This attempt was unsuccessful. Shortly thereafter, the size of the fire was such that extinguishing efforts were abandoned, and the plant manager reported that the fire was spreading in all directions. Up to this point no one had seen effective discharge from the sprinkler systems, although some employees reported seeing “muddy” or “rusty” discharge from the sprinklers.
The public fire department arrived at 12:29 p.m. (four minutes after ignition) and reported that the building was heavily involved in fire. Mutual aid from surrounding areas was requested. By 12:45 p.m., the entire facility was involved in fire and the roof was collapsing. Within 20 minutes of ignition, the facility was virtually a total loss.
When the failure of the automatic sprinklers was investigated, a large number of sprinklers was found to be obstructed by rust and scale. Sprinkler piping up to 1 ½-inches in diameter was also found to be obstructed. Investigators believe that as many as 50 percent of the sprinklers in the area of fire origin may have been obstructed.
Automatic sprinkler systems are useless unless they are properly inspected and maintained. Fire officers and fire inspectors can check test records maintained by the building owner to determine the frequency and results of routine tests. An absence of such records indicates poor maintenance practices that may affect the performance of the system during a fire.
Observation of routine tests on the sprinkler systems can also indicate their condition. If rust, scale, or other debris is discharged or blocks the test connection, it is safe to assume that there is more debris inside the system that could affect its performance.
IMPROPERLY DESIGNED SPRINKLERS
The fourth major reason that sprinklers fail to control a fire is an inadequately or improperly designed sprinkler system. There have been several recent major fires that resulted in sprinklered buildings burning to the ground because the owners of the building presented a fire challenge to the sprinkler system far beyond what it was originally intended to control. This is especially true in warehouses and storage areas where the type, amount, and configuration of the storage has changed since the sprinklers were installed.
A well-known case in point is the Morristown, Pennsylvania warehouse of the K-Mart Corporation. Built in 1976, it was a single-story building that measured 1,085 by 1,180 feet.
The warehouse was used for the storage of a variety of products and materials in racks and in piles. This included toys, clothing, automotive accessories, rubber tires, plastic materials, foods, and nearly every other item that could be found in a K-Mart store. Also included in the storage were a variety of aerosol products and other flammable and combustible liquids.
At first glance, it would appear that a major fire could not occur. The building was fully sprinklered with wet-pipe sprinkler systems that were hydraulically designed to provide a maximum density of 0.40 gpm per square foot over the most remote 3,000 square feet of floor area. Water supplies for the sprinkler systems consisted of a 12-inch connection to a 16-inch public water main, a l,500-gpm-at-80-psi electric booster pump arranged to take suction from the public water main, and a 2,000-gpm-at-128-psi diesel fire pump which took suction from a 300,000-gallon aboveground reservoir.
The fire apparently started in the warehouse when a box of flammable aerosol carburetor cleaner fell from a stack, broke open, and was ignited by a lift truck. This was estimated to be at about 12:25 p.m. Employees attempted to fight the fire with fire extinguishers and a hose connection fed from the sprinkler system, but they were unsuccessful.
Fire department units responding to the scene reported seeing heavy smoke coming from the building as they approached and quickly sounded second, third, and fourth alarms.
The roof collapsed quickly, breaking sprinkler piping. With the sprinklers rendered inoperative and the water pressure decreasing, the fire spread rapidly, and within a short time the entire building was involved.
By 9 p.m., the fire had burned down to a manageable level and was declared to be under control. Fire department personnel remained on the scene for seven days, controlling spot fires as demolition efforts began. An estimated 1.8 million gallons of water were pumped onto the fire on the first day of the fire.
Postfire investigation revealed that all sprinkler systems and other fire protection equipment were in operating condition at the time of the fire. An analysis of inventory records revealed that at the time of the fire the warehouse contained massive amounts of high-hazard materials including 580,000 cans of petroleum-base aerosols; 480,000 cans of alcohol-base aerosols; 47,000 gallons of other flammable liquids in nonpressurized containers; 101,700 gallons of combustible liquids in nonpressurized containers; 19,000 cans of butane lighter fluid; 109,000 disposable butane lighters; 42,000 propane cylinders; and thousands of rubber tires.
Many people, especially those outside the fire protection community, questioned how a facility of this size could burn to the ground even though it was fully sprinklered. After all, why spend the money to install sprinklers if they don’t work? Their questions can be answered by a review of the lessons that were known, but not followed, at the time of the K-Mart warehouse fire.
The design of automatic sprinkler systems must be matched to the hazards they are expected to protect. Ordinary warehouses pose a severe enough challenge for sprinklers without the added challenge provided by high-hazard commodities such as plastics, rubber tires, and flammable aerosols. The automatic sprinkler systems must be designed to match the hazards, or the hazards must be maintained within the fire control capabilities of the existing sprinkler systems. Failure to comply with this basic principle dooms the building to destruction.
But it doesn’t take a building full of aerosols or flammable liquids to overpower the sprinkler systems. Any change that exceeds the parameters of the original sprinkler design can cause the sprinklers to fail Such conditions may include:
- increased storage heights;
- a change in the materials being stored (i.e. higher hazard commodities such as plastics, aerosols, etc );
- storage in the aisles;
- a change in the storage configuration (for example, from floor storage to rack storage).
Since the K-Mart warehouse fire, there have been a number of similar but less publicized losses that contain the same major ingredient: warehouse sprinkler systems that are overwhelmed by the hazard they are expected to protect. Fires of this nature will continue to occur until building owners realize that any change in the occupancy of the building requires a corresponding analysis and change in sprinkler systems.
EXPLOSIONS
In some cases, sprinklers may be rendered inoperative due to an explosion. For example, a piece of equipment may explode inside a building. The force of the explosion or flying debris may break sprinkler piping in the area and render the sprinklers useless. Sprinklers will not prevent an explosion and cannot be expected to minimize the effects of an explosion.
When responding to an incident involving a reported explosion, fire officers should expect the sprinklers to be damaged and anticipate encountering a larger body of fire than would normally be expected. They should also formulate plans to isolate the damaged sprinkler systems to conserve the available water supply for those sprinklers that are still in service.
Automatic sprinkler protection is the most effective fixed fire protection available for an industrial facility. However, the management of the facility and fire officers must realize that sprinklers have specific applications and limitations that must be understood. If they recognize and understand why sprinklers sometimes fail to control a fire, they can be alert to detect the conditions that can compromise the effectiveness of the sprinklers and take appropriate action.
