SHOULD THERE BE A SMOKE CONTROL SECTOR?
FRANCIS L. BRANNIGAN
The first photo below shows the “unbelievable” amount of smoke generated by a one-apartment fire in a home for the elderly in Tampa, Florida.1 Home contents are not what they were in past years. A large proportion of the contents of today`s dwellings originated as “black gold” pumped from the earth. In 1975, the Society of Fire Protection Engineers warned that codes were not designed for the increased fire loads. Recently, occupants of a New York City high-rise apartment died on upper floors as they tried to escape from a fire on a lower floor. There have been a number of other such tragedies.
This item is an attempt to stir up discussion.
I believe the fire service must place far greater emphasis on fire as a toxic gas generator, particularly in high-rise buildings. Should smoke control be advanced in importance by designating a smoke control sector? This officer would advise the incident commander on how tactics might increase or reduce occupants` exposure to the toxic gases. He might direct units that are specifically assigned to smoke control.
All tactics and SOPs should be examined for their effect on distributing toxic gases to occupants awaiting evacuation. If a fire is below the limit of the aerial apparatus, perhaps the traditional inside attack should be changed to an attack from exterior platforms. Charged lines might be laid to interior attack point(s), but no doors would be opened. Attack lines would be stretched through a window. This approach could dump a much greater proportion of the toxic gases out of the building than an attack made in the customary way. Modifying water with wetting agents or Class A foam might be useful in suppressing smoke generation.
It is easy enough to plan that one stairway be used for attack and another for evacuation, but how do we get the information pertaining to the de-signated stairway to people who hardly know the stairways exist, since they always take the elevator?
The assumption that a fire-resistive building provides safe harbors from smoke is not necessarily valid. Most fire-resistive buildings are riddled with channels that will transmit toxic gases to residents.
We must recognize that the key element in life safety of building occupants is not how high the building is but how long it takes an occupant to reach an area safe from all the products of combustion.
A huge mistake made in the wake of the 1911 Triangle Shirtwaist Fire was essentially relating the life hazard to a building`s height, thus requiring sprinklers only in factory buildings more than six stories high. This was based on the reach of the aerial ladder, a limited efficiency rescue tool.
Secondary to the life hazard is property damage. Fire departments have always been blamed for “water damage,” although sometimes it is graciously agreed that it was unavoidable. Smoke damage was regarded as inevitable and totally excusable. At Navy Norfolk, we excelled in controlling water damage, but when I proposed that we stock room deodorizers to mitigate smoke damage, my boss dismissed the idea as “ridiculous.”
I think that smoke damage should be considered as an element of operating procedures. Just imagine the additional damage the smoke seen in the photo above would have done inside the building.
LOS ANGELES FATALITY: UPDATE
The Los Angeles City Fire Department is to be commended for releasing a full report on the fire officer fatality that occurred on March 8, 1998. It is certainly encouraging to find department managers with the courage to make a full report of fatal accidents with the object of preventing such deaths in the future, not only in their departments but in others. In Ol` Professor, November 1998, I discussed the LA City Fire Department`s excellent new policy that requires that a specific “roof safety officer” be responsible for the safety of personnel working on the roof. In the tragedy, units responded to a closed commercial building at 2:20 a.m. “Light smoke showing” was the initial report, too often the first signal of a serious fire. The report says nothing of any automatic alarm or watchman, so we must assume the alarm came from a passerby. At that hour of the morning, few people are out and many of those who are, because of the activities in which they may be engaged, may not be willing to get involved with the authorities by reporting an incident such as a fire. Assume that any late-night fire in a closed building has been burning for some time. It may take hours for the smoke to build up enough pressure to force itself out of an opening.
Truck companies immediately opened the bowstring truss (often called an “arched truss” on the West Coast) roof. The first hole was made by removing a patch over a previous fire vent hole, so venting was rapid. A member of the second truck, sounding the roof with a hook, broke through the roofing. Engine companies were delayed in getting access because of security doors. The door was finally opened with a sledgehammer, which was used “from 10 to 30 times.”
Training texts on ventilation speak of relieving smoke and heat. They should include the fact that 537 Btus are generated for every cubic foot of oxygen consumed by the fire (not just delivered to it).
There seems to be little recognition of the fact that the fire pouring out of your successful vent hole may be consuming the gravity resistance system (GRS) of the roof on which you are standing and under which other firefighters are working. I understand that the main body of fire in the March 8, 1998, tragedy was the roof itself. Reading between the lines, I got the feeling that the incident commander might have been hampered by the absence of an aide. Long ago, many fire departments designated this position as a “chief`s driver.” The existence of such a position leaves it open to bean counters and newspaper reporters looking for “government waste” to have a field day exposing the “wasteful practice of having a “driver” when the mayor or city manager drives himself.
The term should be “aide.” The position should be formalized and not a haphazard assignment. A good chief-aide team is a joy to behold. The practice of grabbing a firefighter from an already understaffed unit to act as an aide is a poor substitute for a team. I am not aware of any volunteer department that has designated chief`s aides, possibly because of the general concept that the aide is primarily a driver. A volunteer chief is just as susceptible to information overload as a career chief. If I`m wrong, tell me.
VENTILATION AND WATER FLOW
As a general rule, ventilation should be coordinated with the ability to put water on the fire, but few rules are absolute. Legitimate theaters (those with scenery and live actors) suffered huge losses of life in the 19th century. Thus, they have long been designed with automatic vents backstage to relieve the pressure on the proscenium curtain that protects the audience from a fire backstage. The backstage personnel, far fewer in number than the audience, are expected to escape through exits provided. It is a given that the fire will be accelerated, but the principal objective–the safety of the audience–is enhanced. In the Chicago Iroquois Theater fire (606 died), a gaslight fixture that projected through the proscenium opening kept the curtain from descending.
In his excellent book Fire (1930), Thomas Dougherty, assistant chief of the Fire Department of New York, offered without charge his patented invention of an automatic vent for installation over tenement house stairways to vent the stairway and thus prevent “mushrooming” of deadly heat and smoke on the top floor.”2
BOWSTRING TRUSSES–UNPROTECTED STEEL: UPDATE
After the Hackensack, New Jersey, disaster in which five firefighters were killed by the collapse of a bowstring truss, many articles in fire service publications placed special emphasis on the bowstring truss. The fact is that a truss is a truss is a truss. All have the same negative firefighter safety characteristics. Longer-span trusses may be more dangerous than shorter-span trusses, but only because the collapse area is greater. One Midwestern fire department defined a truss by the fact that it made a “hump” in the roof (a characteristic of a bowstring truss), and three firefighters in that department died in the collapse of an unrecognized parallel chord truss (because there was no hump) (see Chapter 12 in BCFS3).
On the other hand, in some areas, particularly on the West Coast, there appears to be a greater confidence in timber trusses (sometimes called “arch trusses”) than I believe is warranted. When researching another matter, at my request, my friend and longtime valued associate Walter Maybee, SFPE Fellow, produced this very interesting item from Building Construction as Applied to Fire Insurance by Charles C. Dominge and Walter O. Lincoln, published in 1922: After describing wooden bowstring trusses, the authors state: “This class of roof truss is considered to be the equivalent of unprotected steel” (emphasis supplied). The heavy wood trusses have substantial vital components of unprotected steel.
MASONRY IS NOT LIKE BATS: UPDATE
Bats are designed to hang upside down, but masonry units are not. In earlier times, all masonry walls were solid brick, and firefighters were taught to make a triangular cut, with the apex at the top. In this way, the courses of brick were corbelled out like steps, and the integrity of the wall was preserved. Walls “sense” openings, and a compressive load coming down a wall divides at a point located above the opening, approximately half the width of the opening, and passes down alongside the opening. The triangular cut conforms to this phenomenon.
Not many walls are solid brick masonry today. Many are concrete block. The size of the units make the triangular cut impractical. An improperly cut block wall is shown on page 161 of BCFS3, with the caption citing the need for immediate support. The mortar is simply a bedding material and has no rated tensile strength.
WHERE DO YOU GET THAT “WE” STUFF? UPDATE
Windsor Castle, a home of British royalty for centuries, burned in a spectacular fire some years ago. In a videotape I saw recently, the chief fire officer noted that, as he responded, he wondered whether he would be the officer who saved Windsor Castle or the officer who lost it.
The building was built to burn. A feature of all such buildings is a set of hidden interior corridors and stairways so the servant class can go about its chores without being seen. The castle staff diddled around before calling the fire brigade. In rebuilding, Their Majesties, in their regal wisdom, refused to allow sprinklers “because they might damage the art works.” Why should the chief fire officer even think he was responsible for the loss?
This attitude is common in our fire service also. We need an attitude change. When appropriate, point out that we didn`t create the problem. We didn`t start the fire. We didn`t delay the alarm, which permitted the fire to grow. We didn`t build the building so that it was an easy burner. We got involved only when somebody fouled up and we were called to fix the problem.
POST-TENSIONED CONCRETE GARAGES: UPDATE
In Ol` Professor, March 1998, I discussed the catastrophic collapse hazards of cast-in-place concrete under construction and included a photo of the post-tensioned parking garage that partially collapsed in Bailey`s Crossroads, Virginia (see pages 354-356 of BCFS3 for details on this catastrophic hazard).
A number of such garages are in trouble because of the destruction of tendons by penetration of water (probably contaminated by snow-melting salt) into the tendons.
Fire departments should be aware of all post-tensioned buildings in their areas. The AIA and the Post Tensioned Concrete Institute have fought off the efforts of the demolition contractors to have such buildings permanently marked. Some building departments may destroy records after a few years to “save space”–French for “get rid of the evidence.”
NOT JUST A CHIMNEY FIRE: UPDATE
In 1971, I was engaged as a consultant by the National Bureau of Standards (now the National Institute of Standards and Technology) to study the construction of, and investigate fires in, so-called “protected combustible structures” to determine the reason so many fires spread rapidly beyond the area of origin. Such buildings are of wood construction with gypsum sheathing to protect the wood from fire. I found that the sheath protection was a myth because there were too many penetrations in it and because fires could originate behind the sheath (see Chapter 5 of BCFS3).
At that time, the upgrading of the simple post-war garden apartment concept had begun. Metal duct chimneys made it possible to provide a fireplace in each of the new upscale apartments. The ugly pipes were often grouped and enclosed in a wooden chase without gypsum sheathing. A Florida builder, ashamed of the metal chimney pipes, surrounded each pipe with a brick masonry wall that looked like a chimney and rested on the roof. On a chilly night in an Orlando suburb, a tenant burned a rubber tire in his fireplace, producing heat far above the chimney`s rated capacity. During the resultant fire, the “chimney” crashed down into the second floor, fortunately, without causing any injuries.
In Fairfax County (VA) Fire and Rescue`s publication In Line (March-April 1999), Captain J. Robert Ferrule tells of two “Second Alarm Chimney Fires.” Smoke coming from the wooden enclosure was assumed to be coming from a stack. A chimney fire response of an engine and truck was dispatched. In each case, the incident commander found himself working a structural fire with a limited response that would not be augmented for several minutes. The article contained the following observations and recommendations:
The initial engine reverse laid two lines to the hydrant–one for the attack, the other to supply the second engine in.
The various voids in the building, including truss-floor voids, are wide open to extension. When fire burns through the exterior skin, air is supplied to the extending fire.
Structural members, such as truss floors, may already be weakened, although there may be no apparent indication of the weakening. (Author`s note: This is another situation in which a thermal imaging camera would be priceless.)
Each area to which the fire has extended is a separate fire area.
Avoid attacking the fire between the source and the most remote extension. Don`t push the fire into the unburned area. Try for a position in the unburned area, and drive the fire back.
Be wary of using positive-pressure ventilation early; it can push fire through the building void in minutes.
Fire investigators have noted several cases in which rodent nests in the void have caused the chimney and, in turn, the structure to ignite (thanks to Fairfield County Fire Rescue Chief Edward Stinette).
It might be useful to train dispatchers to ask when a chimney fire is being reported, “Is it brick or metal?” If metal, a full response would be warranted.
The building is your enemy. Know your enemy.
Photo courtesy of Tampa Fire Rescue.
The shoring of the garage that collapsed in Bailey`s Crossroads, Virginia.
The replacement of the tendons that failed. The hydraulic pump that tensions the tendons (jacks the cables) can be seen in the center of the photo. A post-tensioned building is a different building forever. Any sign of shoring means trouble. Become fully informed about the problem. [Photos courtesy of Lieutenant Michael P. Regan, Fairfax County (VA) Fire Rescue.]
1. See “High-Rise Residential Fire, Tampa, Florida,” Emilio F. Salabarria and Leslie P. Ennis, Fire Engineering, August 1999, 118-122.
2. I loaned my copy of this book to every superior I had during my career, for its wonderful exposition of what fire safety, fire departments, and firefighting are all about. It would make a wonderful reprint.
FRANCIS L. (FRANK) BRANNIGAN, SFPE (Fellow), the recipient of Fire Engineering`s first Lifetime Achievement Award, has devoted more than half of his 57-year career to the safety of firefighters in building fires. He is well known for his lectures and videotapes and as the author of Building Construction for the Fire Service, Third Edition, published by the National Fire Protection Association. Brannigan is an editorial advisory board member of Fire Engineering.