AMBIENT AIR SUPPLY TO HIGH-RISE FIRES: UPDATE1

BY FRANCIS L. BRANNIGAN, SFPE (FELLOW)

A caveman discovered that if he blew gently on a fire, it would increase. Bellows were invented to provide a stream of air to accelerate the fire. In industrial plants, huge bellows were used. Finally, mechanical air blowers were developed.

More than 30 years ago, air-conditioning engineers discovered smoke and set out to graft smoke removal onto air-conditioning systems. One enthusiast argued that the fire could be controlled by regulating the air flow. At an annual meeting of the International Association of Fire Chiefs (IAFC) he declaimed, “Let the fire burn, but let it burn clean.” This incomprehensible statement completely ignores the tremendous heat generated by the fire. In addition, all around the “clean burning” fire, materials are being degraded into toxic products without any comment. It is not possible to control an imbecile statement made at a meeting you sponsor, but you should not give it the cachet of your organization. If you must publish it, include the adequate discussion of the fallacy. Most of what I know about this subject came from my mentor, Fire Department of New York (FDNY) Deputy Chief (Ret.) Elmer Chapman, one of the most knowledgeable persons in the fire service on smoke control. (See BCFS3, pages 489-490, for solid information from an expert.)

THE WIND

If your first significant high-rise fire occurs on the lee side of the building, you may find the fire a “piece of cake” and be badly misled. A failed window at a fire on the windward side of the building can make the fire a roaring inferno that your hoseline(s) in the corridor cannot hit.

The first such fire I know of occurred in Chicago. It was impossible to get into the first floor until the fire burned out.

New York City has experienced a number of fires in which the wind made fire suppression virtually impossible. FDNY Battalion Chief John Norman has developed a tactic that offers great promise, but at this writing, it has not been tested at a fire. Fire Engineering will report more on this as information becomes available.

The wind is unstable. A few degrees of shift can make a marked change in the fire situation. When units are attacking a significant high-rise fire, an observer should be assigned to observe the wind conditions at the fire floor and to pass this information to the interior command. Most particularly, the fact that window(s) have failed should be transmitted.

INSUFFICIENT WATER

I am aware of all the reasons for going up with small hose in the high-rise pack. But some fires require big lines. I think every unit should carry at least one length of 21/2-inch hose, prepped for carrying, so that a big line can be made up faster than pulling off hose, separating lengths, and rolling them up, as one fire department had to do in a serious high-rise fire.

A POSSIBLE HAZARD

Some officers ride to fires with the radio mike on their chests. Would this cause serious injury if the air bag deployed? Any comments?

EXTENDED CORNICES: UPDATE

“Dangerous Roof Styles: The Extended Cornice” by Anthony Avillo (Training Notebook, Fire Engineering, October 1999) presents a hazard I had not previously realized. We usually think of a cornice as a structure erected at least partially on the roof that acts as a barrier to falling off. Avillo presents the extended cornice, in which the roof is extended out over the cornice without any barrier. Falling cornices have caused many deaths and injuries, including those of firefighters in aerial platforms.

It is very easy for a firefighter to walk right off the roof in smoke, particularly if he accessed the roof by an inside stairway or another building. Additionally, the cornice may be burning, and the condition may not be visible. The collapse of the cornice would drop the firefighter to the ground.

Get the tower ladder up in the air and survey your area for extended cornices and the sides or backs of roofs without parapets. Note these hazards in your record and retrieval system. While on the subject, there may be many buildings with high cornices and false walls. Before getting off the aerial, be sure you have a way to get back on. Never forget about the additional exits that should be provided whenever personnel are sent to the roof.

I saw a ladder company trapped on the roof of an eight-story building. The life gun was laid out to shoot them a line. Three firefighters walked a 185-pound, 35-foot straight ground ladder up an aerial that had been extended to the roof of an adjacent five-story building and rescued them. All agreed later that the ladder should have been put in place when they went on the roof.

STEEL SANDWICH POLYSTYRENE PANELS: UPDATE

In News in Brief (Fire Engineering, March 1999), Factory Mutual expressed concerns with steel sandwich panels in which the filling is expanded polystyrene (EPS). They burn furiously and would require a special line of wet pipe sprinkler along the wall. Alternatively, Factory Mutual requires an approved gypsum board thermal barrier. This also applies to metal deck roofs with EPS barriers. Thermal barriers may pass laboratory tests, but the reliability of the gypsum board in place is questionable because of the ease of physical damage. I would be wary of entering any such area. Use a thermal imaging camera (the firefighter’s radar) to determine if fire is behind the gypsum board.

Gypsum board is an excellent barrier to the spread of fire, within limits. If the fire penetrates the gypsum board or starts behind it, the gypsum board becomes a barrier to firefighters’ seeing where the fire is located and getting water to the fire.

Steve Corwin of Oregon sent an article from United Kingdom-based Fire Research News about large insulated sandwich panels (LISPs) in buildings. These panels are a metal sandwich and are filled with EPS, polyurethane, or noncombustible mineral fiber. Such panels are used in lightweight steel structures.

Two firefighters lost their lives in a fire in a chicken processing plant in England that included LISPs in its construction. The hazard of these panels is not apparent to the casual observer, since the filling is invisible. Reports of fires involving these panels universally related large quantities of black smoke and some collapse of panels.

If you have such steel buildings in your area, ask the management about the contents of the panels. The United Kingdom Home Office recommends diligent attention to housekeeping and integrity of exits for occupants. A fire in the building could quickly involve the panels and generate so much smoke that occupants might not escape. Check for any further developments. In earlier years, such panels were filled with low-density fiberboard. Fire can burrow into the board, and it is then necessary to tear each panel open.

ANOTHER “FIREFIGHTER RADAR” SUCCESS: UPDATE

Acting Deputy Chief Dave Mager of the Boston (MA) Fire Department told me of a fire in a four-story ordinary construction building under renovation. The building was heavily charged with smoke. Using a thermal imaging camera, Rescue Co. 1 detected holes cut in the floor for dumping debris and for a new elevator shaft. All units were warned, and there were no injuries. I would appreciate receiving and will pass on any stories of success and failure and any cautions involving these new devices.

During World War II, there were some senior naval officers who didn’t believe in the little blips on the radar screen, and it was necessary to send them to school to train them. On the other hand, those with special but limited knowledge may get an unwarranted feeling of superiority.

Some of our fire school instructors were impatient with sailors who couldn’t get the hang of firefighting procedures. I arranged to take groups to visit ships of crews we were training so they could see the complicated tasks performed by their students in their own environment, particularly radar and sonar operations. The dose of humility brought about some necessary attitude changes.

MY DREAM

In the March 1998 Ol’ Professor column, I wrote of my terrifying nightmare-the collapse of concrete buildings under construction with the possibility of scores of firefighters crushed by the rubble (see BCFS3, pages 342-348).

My dream is as follows. “Put together a structure with wood trusses from a demolished building (trusses would thus be dry and seasoned) and with no basement ceiling. Furnish basement with the typical polyurethane furniture. Get a fire going good and, 15 minutes after ignition, have some truss representatives and lawyers suited up and masked to make a primary search for victims!”

WRITING EXAM QUESTIONS

Some of you have the very difficult task of writing exam questions. The New York Times provides a pertinent standard: “Write (the question) not so that you can be understood but that you cannot be misunderstood.”

From time to time I see examination questions derived from BCFS3. In many cases, the question was improperly written or the “correct” answer was not supported by the text. Many questions work to the disadvantage of the well-informed candidate. A question may demand a flat affirmative answer. The candidate is aware of a significant but not well-known exception. Does he guess the examiner is not well-informed in all the details, or does he act on his knowledge and prepare for a legal battle?

When I was an officer in the Naval Firefighting School at Norfolk, Virginia, in 1944, we had the opportunity to promote 20 third-class firefighters to second class. At the time, the Navy put alcohol aboard aircraft carriers for injection into fighter aircraft engines. This would temporarily add 15 knots to the plane’s speed, which helped the pilot break away from a lighter and more maneuverable Japanese Zero on his tail. [A knot equals one nautical mile (6000 feet) per hour.] Conventional foam was not effective on polar solvents such as alcohol, which pulls the water out of the foam. A special Alcofoam™ was available, but the special application requirements were beyond the ability of lightly trained sailors. The doctrine, therefore, was to dilute the alcohol with water.

The question I asked was expected to draw the answer, “Don’t waste time with foam-it won’t work. Dilute the alcohol with water.”

One candidate argued, “You didn’t specify how much fire or foam. I envisioned a 55-gallon drum with a foot of alcohol in the bottom and I had three 21/2-inch chemical foam lines.”2

NEW CONSTRUCTION, OLD PROBLEMS: UPDATE

The excellent article “New Construction, Old Problems” by Allen B. Clark, Jr. (Fire Engineering, April 2000) should be clipped and saved, since this type of construction will become more widespread. Note that even if foamed plastic doesn’t ignite, it will melt.

Using a gas torch to demonstrate fire resistance is not valid. While the torch does have a high temperature, the volume of heat is not at all comparable to a large body of fire or a sustained heat source.

At an Atomic Energy Commission plant, radiation shielding material was installed on the bottom of a glove box enclosure3 for plutonium metal to guard against any exposure to workers possibly working under the enclosure. Plutonium is a naturally self-heating substance. Pieces of plutonium in metal cans similar to those used for tuna had previously been spotted on heat sensors to detect any heating. The shielding material-a heavy, dense wood product similar to Masonite™-had been “tested” for ignition with a blowtorch and “passed.” The sustained heat of an overheated can was another matter. A severe fire resulted, one of the most costly in American history. The physical damage was about $1 million, but many millions more were spent to clean up the fire-dispersed plutonium. The plant fire department was commended by the Atomic Energy Commission for limiting the loss. History is silent as to the fate of scientists who avoided an exotic radiation hazard only to create a plain-vanilla fire hazard.

BX CABLE REVISITED

In the March 2000 Ol’ Professor column, I spoke of a fire started by a BX cable. I received a letter from Prentice Cushing (see Letters to the Editor, page 46). He’s a senior member of the Institute of Electrical and Electronics Engineers and a fellow of the American College of Forensic Examiners.

He writes: “If a neutral conductor on the service entrance opens, then the only neutral path becomes the ground (not intended to carry current), and I have seen many cases where the BX armor became the path from a fault to where the cable touches a water pipe and supplies a water pump or water heater; as a result, the armor overheats and starts a fire.”

Regarding the above paragraph, a number of years ago, the Smithsonian Institution suffered a devastating fire. A large display with hanging sheets of clear plastic and a number of electrical devices was built up on a wooden platform. As a result of some defect, the entire mass of armored cable became “like a large toaster.” This fire has a number of useful points which I will relate in a subsequent column.

Endnotes

1 “Update” indicates building information not specifically covered in BCFS3.

2 Chemical foam powder consisted of a mixture of sodium bicarbonate, aluminum sulfate, and a stabilizer such as licorice. The powder was dumped into a hopper and mixed in a 21/2-inch hoseline with 100 to 150 feet of hose downstream with a long two-inch nozzle. During World War II, mechanical foams came to the forefront.

3 A glove box enclosure has heavy gloves attached to ports that allow workers to manipulate materials in the enclosure with tools but avoid breathing in any particulates released inside the box. This particular glove box enclosed an entire assembly line.

FRANCIS L. BRANNIGAN, SFPE (Fellow), recipient of Fire Engineering’s first Lifetime Achievement Award, has devoted more than half of his 58-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.

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