Understanding the Core: Part 2

July 1, 2005
Curtis S.D. Massey introduces the second installment in this series with "Techniques of Stairwell Operations And Utilizing Building Services In High-Rise Commercial Fires".

As stated in the first installment of this article, in any high-rise fire, it is vitally important to understand everything there is to know about the area from which most operations will be originating – the core. This installment continues an examination of characteristics, features and oddities of core configurations and their performance during fires, including stack effect. The information is based on office buildings with two primary exit stairwells – the most common configuration in properties with small to medium-sized floor plates.

Stairwell pressurization. Modern high-rise office buildings are often designed with stairwell pressurization capability. This is where a stair shaft is fed by supply fans that activate during a fire, creating a positive pressure within the shaft so fleeing occupants are not followed by smoke entering the stairs behind them. This eliminates the need for a smoke tower and frees up precious space within the core where the vestibule and smoke shaft would be located, allowing for a more efficient, profitable use of the core. The advantage is stated above, but the disadvantages are two-fold. One, if more than a few doors are opened at the same time in the shaft during a fire, the positive pressure goes away due to the inability of the fans to overcome the increased demand. The stairwell just becomes the typical enclosed stairwell and smoke migration occurs. Two, once the attack team advances its hoseline out of the stair onto the floor, the rush of positive-pressurized air will follow them, feeding the fire fresh air/oxygen and possibly making the fire more difficult to control, although visibility would be improved. Tests conducted in high-rises using both fire department fans and building mechanical fans to provide stair pressurization resulted in some smoke migration into the stairs regardless of the positive pressure being provided. Doors being opened into the stairs by tenants can also be difficult to open by people small in stature, due to the force of air pressure against the opposite side of the door. Firefighters attempting to enter floors will have to overcome the same resistance until the door is separated from the seal. The capacity of fans in cubic feet per minute (CFM) can vary greatly. Note that there is also a smoke tower and positive-pressurized stairwell combination (see Graphic E). This is probably the most effective idea to date regarding positive and negative ventilated stairwells from an evacuation standpoint. Standpipes. In Canada, the norm in most cities is for the hose connections to be outside the stairs. The intent is to avoid contaminating the exit stairs as a fire is being attacked while occupants are evacuating. In the U.S., it is common to find the standpipe connections in the stairwells, or possibly in adjacent vestibules if smoke towers exist. You can also find auxiliary hose cabinets out on the floor near the exit stair and/or out in tenant spaces far removed from the core (usually 1½-inch outlets with “first-aid” fire hose), depending on code requirements for floor coverage. The attack stair must be compromised due to the fact that most standard operating procedures (SOPs) dictate that the attack line is attached to the standpipe one floor down, then flaked out within the stairs (including a loop up to the next stair landing a half-floor or more above the fire, then back down to allow for easier advance of the lead line once it is charged). Any door to the fire floor is then propped open, so the line will not be kinked, and the hose is advanced onto the floor toward the seat of the fire. If the connection is not in the stairwell, then the door below the fire floor must be propped open as well (see Graphic F). The stairwell will almost certainly be subjected to the by-products of fire and will affect the fleeing occupants descending from upper floors. The Canadian method keeps the stairs mostly intact, which is a major plus for the tenants. However, both methods possess major flaws. Conceptually, attaching the initial attack line on the fire floor out in the hallway exposes firefighters to great risk. It may work well in small residential or hotel fires where the fire will almost always be contained to the unit of origin because of compartmentation (barring auto-exposure, fire penetrating poke-throughs or entrance doors in the main hallway left open by fleeing occupants), but what about an office building fire where you can have large, open floor layouts with a massive fire loading present? How do you find the cabinet and connect your hose in heavy smoke, even if the fire is not close? Visibility can be reduced to zero within seconds of leaving the stairwell. What if the hoseline bursts, hidden fire above the suspended ceiling drops down onto or behind the attack crew or if flashover occurs and overwhelms the attack team, forcing a rapid withdrawal to the stairwell? The hose is your lifeline, but in this application it will only lead you to a cabinet on a blank wall. Then, in the heat of the moment and in dense smoke conditions, you must choose whether to go left or right to reach the safety of the stairs. The members of the attack team may remember which way the stairs are located and only a slight delay will occur, but what if the team that attached the hose has been relieved by a second crew that went from the stairs directly to the nozzle and when conditions suddenly deteriorate, panic ensues in their attempt to find the safety of the stairs? If those firefighters go the wrong way while fighting through debris and wire from a collapsed ceiling and/or heavy fire conditions, they are endangered. Another question: Where would the backup line come from? On a working fire, a backup line must be stretched and safety concerns would preclude it coming from another hose cabinet on the fire floor, so it should come from the floor below, thus compromising the stairwell. In the U.S., it is accepted practice in most departments to connect in the stairs if possible (or from a hose cabinet on the floor below, if it is not in the stairs) and come out on the fire floor with a “loaded gun” in your hands, offering firefighters maximum protection and a line that will lead them directly back to their means of egress if conditions warrant a rapid evacuation of personnel. Unfortunately, smoke (toxic gases) and heat will enter the stairwell, endangering evacuees. Obviously, one method enhances protection to the building occupants while reducing the protection of the firefighters. With the other method, the opposite is true. The point is there is no true method that provides superior protection to both firefighters and civilians. (Note: High-rise buildings do exist that only have one standpipe, creating myriad problems for attack teams, especially if the riser should fail or is compromised in any fashion – bombs, gas explosions, earthquakes, aerial assaults by terrorists – and fire is beyond reach of “exterior standpipes”, i.e., aerial ladders. Also remember that standpipe valves are rarely, if ever, exercised. They may easily be stuck in the closed position through lack of use and require the use of standpipe bag tools to open them. Attack lines. Much debate exists on what is the best attack line to use on a high-rise office building fire. Diameters can vary from 1½ to 2½ inches in the U.S. The obvious advantages of the smaller attack lines is rapid deployment, increased mobility in weaving lines around walls and furniture, and the minimal manpower required to put the line into service. Simply put, you get water on the seat of the fire in the shortest time possible. If the fire is of any size beyond a very small room-and-contents fire, however, the water flow may not be sufficient to overcome the BTUs being generated by the fire. The crew is also at greater risk if flashover occurs. With larger handlines, the opposite holds true – longer deployment times, difficulty in advancement and greater strain on manpower to put the line into service, but deeper penetration with superior “knockdown” power and better protection of personnel exists. Each has its pros and cons. Yet, in today’s high-rise office buildings possessing large, open floor areas (cubicles have mostly replaced walled offices) and a substantial petroleum-based fire load generating massive BTUs from the burning plastics and synthetics, a large-diameter handline is almost dictated as the only relatively safe, effective method of fire control. These fires are just too hot and intense for smaller lines to be effective. In addition, there are fewer problems with water flow using larger lines if pressure-regulating valves (PRVs) or flow restrictors exist. If PRVs are present, be aware that correct system pressure must be maintained for them to function properly. They must also be set to match your equipment. Buildings erected many years ago in some cities have been found to have their PRVs set to match the firefighting equipment at that time – 2½-inch lines with smooth-bore nozzles. Since then, cities that adopted the use of smaller attack lines with fog or high-tech nozzles that require higher operating flow pressures have found that the PRV settings in their buildings were inadequate. Some PRVs cannot be adjusted in the field, as they are set at the factory and have no adjustment capabilities. This can prove to be an issue on a working fire where the PRV cannot be adjusted or removed from the standpipe by firefighters. Use of stairs in fires. Once the chief arrives at a fire involving an occupied high-rise building and assumes control of the lobby command post, he or she will typically designate one stairwell for fire attack and the other for search/rescue and evacuation of tenants. When the attack stair is chosen, the tenants must be advised via the public address system (if one exists) that this particular stair should not be used to evacuate. Prior fire warden training should have provided education in this area, so the tenants know why this needs to be conveyed and what it means. They will know that when the fire attack is initiated, this stairwell will be compromised once the door is propped open. It will be contaminated with smoke and filled with firefighters, hose and other equipment. There will be a mass of firefighters at that stair landing and below blocking their means of egress as the attack is mounted. Toxic gases will be introduced into that stair, especially carbon monoxide (which is a poisonous, lighter-than-air gas), and can kill people on upper floors far removed from the fire. By this time, it is hoped that the initial evacuation floors (optimally the fire floor, two floors above and two floors below) have been cleared and then other possible evacuees can be directed to the opposite stair – the evacuation and search/rescue stair. This stairwell’s door must be kept closed as much as possible, so the fleeing tenants have at least one stairwell that should be mostly smoke-free. One issue may arise early into the operation: Where is the backup line going to come from? The attack stair, where there is already a fair amount of “spaghetti” and chaos? Or the other stairwell, which would make for an easier, less confusing line deployment (providing that lines are not opposing each other), but will compromise that stair as well with smoke, etc.? The best option (especially for the occupants) usually is to try and advance all lines from one stair. Either way, both stairs must be searched their entire height for trapped occupants. Fire department personnel should anticipate a confused, directionless population as a worst-case scenario in the event there is no effective fire warden and training program in place. Locked stairs. Most office buildings keep stairwell doors locked due to security concerns. Some cities require a re-entry floor every three to five floors where the doors are always unlocked or are unlocked at a fire alarm. Modern skyscrapers have automatic stair door unlocking devices that releases the door locks during alarm, allowing re-entry to all floors, or at least re-entry floors; in Canada, they are referred to as “crossover floors” so tenants can be wisely moved over to the evacuation stair. (Note: These doors will not unlock during non-fire related emergencies such as gas leaks, technical rescues, hazardous materials and weapons of mass destruction attacks unless the building has a lobby manual release switch, a pull station is activated or the building is manually put into fire alarm mode.) Older buildings usually have mechanical locks requiring a key to gain entry to a given floor. This can prove deadly to tenants trapped above the fire where smoke is present, especially if they are in the attack stair, which will almost certainly be contaminated. Such locks will also inhibit firefighters trying to make entry on upper or lower floors that must be searched, as well as the attack and search teams on the fire floor itself. Having to resort to forcible entry can be cumbersome, draining and time consuming, delaying operations. On arrival, acquire stair master keys, if available, before ascending. Consider the use of blank card keys with adhesive backing strips to block the door keeper. This would maintain the integrity of the shaft, while keeping the doors “unlocked” for both tenants and firefighters needing entry on each floor (it may also reduce the potential of doors being propped open by tenants fearful of being trapped in the stairs, as well as numerous forcible entries by firefighter search crews with no keys). Multiple teams of two to four firefighters each could grab a stair master key for each stairwell and start unlocking doors, beginning with the fire floor on up. Another pair of teams could start at the top of the building and begin working their way down each stair, unlocking doors and sealing off keepers as they go. Attempt this only if upper-floor elevator access is safe and feasible or roof heliport access exists, as in Los Angeles. This will greatly enhance the efficiency of upper-floor attack and search operations, while greatly minimizing the chances of civilians becoming trapped in smoke-filled stairs. It is important to note that automatic door releases in newer buildings cannot be counted on to function properly in a fire. One fire department recently tested these devices in its high-rise district. In one building, all the door releases failed to operate on every floor, while in another building, half of the doors failed to release, probably from design, installation or hardware flaws. Roof access. Some high-rise office buildings have only one stairwell that goes to the roof; in others, they both go to the roof. You can also find buildings where neither one goes to the roof – they discharge into mechanical decks, usually one floor below the roof and a roof access stair or ladder/hatch must be located to gain roof access. Still yet, there are some buildings that have no roof – only a spire topping off the building (the Chrysler Building in New York City and One Liberty Place in Philadelphia), with the building diminishing up to its pinnacle – or flat-surfaced angular tops, such as the Citicorp Building in New York City or 150 N. Michigan Ave. in Chicago). If a building has a roof and it can be accessed by only one stair, that stairwell may be the optimal one to designate as the evacuation/search and rescue stair, since this gives upper-floor search teams an “out” if they run low on or out of air and cannot descend past the fire floor to safe haven. They certainly may not be plucked off the roof by helicopter “Hollywood style,” but it can be an area of temporary refuge until they can be rescued. Some departments prefer to use this stair as the attack stair, since they may be able to ventilate smoke from it while fighting the fire. One key factor to consider is that the smoke may not make it to the roof in taller buildings, due to the smoke cooling as it ascends and “stratifying,” or leveling off, at floors below the roof level when there is no significant stack effect taking place from temperature/pressure differentials inside and outside the building. (Note: The Los Angeles and San Diego fire departments have highly effective roof helipad/helicopter fleet programs for tall buildings that could prove valuable in high-rise fires or earthquakes. These are the exceptions rather than the rule.) Staging. Usually, staging is set up two floors below the fire floor, since in most high-rise fires there will be at least some smoke migration to the floor directly below the fire. This also allows firefighters taking a breather to be a little farther removed from the battle, so they can get some efficient rehab out of their break. Equipment and manpower can be drawn from this area up to the attack floor or floors while firefighting and searches are being conducted. “Stairwell support teams” should be in place to do nothing more than ferry equipment back and forth to crews working on the floors above. Communications. Two of the biggest logistical headaches a fire department must face in every high-rise fire are air supply and communications. Replenishing air cylinders as fast as they are used up and communicating with crews operating within the building are major issues in most fires. The frame of the building creates enough density (or mass) that it inhibits the ability of fire personnel to talk to each other, especially when transmitting and receiving signals between the command post and upper floors. The FDNY possesses a powerful “post-radio” system that works extremely well in tall buildings, penetrating floor levels from lobby to roof. Other factors such as solar tinting on windows can interfere with talking to the dispatchers or crews outside the building. Companies “stepping on” each other’s transmissions will also occur, in addition to portable radio batteries dying well into the firefight with few to no replacements readily at hand. Always seek other options that may be available early into the fire, in case communications begin to break down. There can be other sources, such as firefighter or fire warden phones or radios that can be commandeered from engineering, management and security personnel (they may also have the advantage of an internal repeater). Elevator or stairwell intercoms may also exist, as well as a public address system that can be used to communicate vital orders to crews on upper floors that are not acknowledging the incident commander’s radio transmissions. Cell phones and land lines can also be used. If you are searching a floor and cannot communicate an important message to the command post, consider picking up a telephone on someone’s desk and calling the dispatch center to relay the message. It wouldn’t be a bad idea for the chief’s aide to jot down the telephone number to the lobby security console and hand it off to company officers as they enter the building. Full versus partial building evacuation. Despite code guidelines and fire warden training, controlling a high-rise office building’s occupants will be difficult. Post 9/11 worries cause many buildings to completely self-evacuate during small fires or even standard fire alarms, disrupting the fire department’s wishes to “defend in place” during minor incidents. Ideally, the incident commander would like to move only the floors that are being affected by the fire, but this flow of people may not be controllable. Half of the egress capacity of the stairs will have to be given up to the firefighters ascending certain areas. If the attack stair is properly commandeered/cleared by the fire department, the tenants are now down to one-quarter of the building’s designed stair capacity as they descend the evacuation stairwell (see Graphic G). Due to the implementation of sprinklers, compartmentation and other ideas, modern buildings’ stairwells are not designed for full building evacuations. They can be extremely narrow. Rapid ascent teams. Possibly, the concept may evolve where major city fire departments with a large concentration of high-rise buildings implement a specialized squad of approximately four to six firefighters as a high-rise unit whose sole purpose is to arrive on scene and make a rapid ascent to the upper floors of tall buildings. They would be comparable to a police department SWAT team – a unique tactical unit dedicated to specialized assignments beyond their regular duties. View it as an altered form of a rapid intervention team, but for civilians. The rapid ascent team would consist of personnel in top physical condition, wearing lightweight Nomex non-structural firefighting clothing and running shoes, along with lightweight 45- to 60-minute self-contained breathing apparatus (SCBA) and helmets clipped to their light coats. They would carry only basic forcible entry tools and radios. Their only assignment would be to gain access to upper floors and give a size-up of all critical conditions to the lobby commander from within the core, in addition to providing direction to fleeing occupants, especially in the attack stairwell. We all know what a tremendous task it is for firefighters to climb tall buildings wearing full structural firefighting gear and fire helmets, compounding the inability of the body to release heat, as well as heavy boots not intended for climbing. Combine that with heavy equipment and the assignments become even more daunting. With buildings ascending to greater and greater heights, they are slowly putting them beyond the ability of fire departments to reach the tops for firefighting and search/rescue purposes if elevators are lost. The strain on fire resources may be unbearable. Some firefighters attempting to reach upper floors of the World Trade Center on 9/11 were collapsing from exhaustion due to the demands of climbing such tall buildings. In Dubai, ground has been broken on a building that will be 160 stories, or 2,640 feet, tall – a half-mile! How many firefighters in structural gear could reach the top floor? Members of the rapid ascent team also would be trained to at least the EMT level so they could provide basic medical assistance on upper stories where feasible. With their forcible entry tools, they could clear a path through debris to free trapped occupants above them if stair shafts are compromised. If the team’s services are not needed at the top of the building, they could carry out the assignment of splitting into two crews and begin descending the stairs, unlocking doors with master keys and blocking the keepers at each level to allow re-entry, but still maintaining the door seal. One may wonder whether the tenants who reported the stairwells to be “blocked” after the twin towers were struck on 9/11 and resigned themselves to their own demise might have been looking down at sheetrock, which comprised the bulk of the World Trade Center’s core, including the stairwell walls, not concrete. Although budget constraints would probably preclude the idea from becoming reality, it isn’t an unattainable goal, especially if existing units are tapped and refined. Homeland Security funding for it may even be available. The idea could pay huge dividends on “the big one.” (Note: The Chicago Fire Department has become the first fire department in the world to adopt and implement this concept. Scores of occupants trapped above the fire floor during the December 2004 LaSalle Bank Building fire were rescued by the department’s newly formed rapid ascent teams. No civilians or firefighters were lost during this major multiple-alarm fire. The Toronto Fire Service utilized the concept successfully as well during an April 2005 high-rise residential fire. All rescues were accomplished with no loss of life. It may be the way of the future in cities with tall buildings.) In summary, it is of vital importance to understand how a high-rise building’s core can work for you and work against you. Most people regard the primary exit stairs as a safe area of refuge during a fire, but they can also be death traps, depending on conditions during the fire and how the attack unfolds. Outlining how fire departments operate during high-rise fires, how to avoid becoming a victim and what to do if you become trapped should be stressed in all tenant fire education classes. Remember that firefighters are operating within a chimney and the building will react as such during the fire. Although searches of upper floors can take an inordinate amount of time (up to 30 minutes per floor in dense smoke conditions) and drain resources, the building must be searched top to bottom, especially in areas where civilians can become trapped in vertical shafts, such as elevators and stairwells. The key to a successful outcome is addressing both the needs of the fire department in attacking the fire and the needs of the tenants who may be in harm’s way, requiring assistance. Curtis S.D. Massey will present “The Art of the 21st Century High-Rise: Fire Department Operations” at Firehouse Expo 2005, July 26-31 in Baltimore. Curtis S.D. Massey is president of Massey Enterprises Inc., the world’s leading disaster planning firm. Massey Disaster/Pre-fire Plans protect the vast majority of the tallest and highest profile buildings in North America. Massey also teaches an advanced course on High-Rise Fire Department Emergency operations to major city fire departments throughout the U.S. and Canada. Part 1 was in the January 2005 issue.

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