Three cheers for Chief Michael Walker’s excellent article “Fog Nozzle Training: Are We Creating a Hazardous Impression?” (Fire Engineering, October 2010)—finally, a fact and experience-based nonemotional assessment of the use of fog streams for aggressive interior fire attack. We would like to offer the following additional insights on stream selection for interior fire attack based on our experiences, research, and practical applications.
In place of the “left for life, right for reach” mantra taught to unsuspecting recruit firefighters, we offer this one: “Left for lobster, right to fight.” We did not coin this, but the point is pretty clear: Turn left for fog and to steam burn yourself and your crew during an aggressive interior firefight. Turn right to fight an aggressive interior fire attack and extinguish the fire safely. Left for lobster generally results in the engine crew’s not being able to proceed through the first room of fire, ending in the building’s dying a slow death.
We wholeheartedly agree with the author’s assumption that the idea that a fog stream will protect you during a flashover likely came from propane training. Fog patterns work extremely well for flammable gas and other similar applications like hydraulic ventilation. However, as we have stated for years, you can’t take parking lot “experience” with a hose stream and translate that into what happens inside a fire building. In the parking lot, the fog stream draws air from behind the nozzleman and directs it out, away from him. There is an unlimited amount of air behind the nozzle and an unlimited amount of space to push it beyond the nozzle.
In a fire building, there is an unlimited amount of air behind the nozzleman provided by the open door he entered through but not an unlimited space to push all that air. The fog stream is so effective at moving air that it will actually overpressurize the room (in front of the stream), driving superheated steam back onto the engine crew. This will occur even if there is an adequate vent opening in front of the attacking fog nozzle. If you have any doubt, try it yourself in your training buildings or acquired structures. Put up a couple of lines of mason twine across the room and tie survey tape to it as air-flow indicators. This will clearly show you the real air movement patterns inside caused by a fog stream without endangering your firefighters.
It is critical to understand the huge volume of air that is moved by a fog stream to understand how it becomes so dangerous inside. We measured the air flow caused by a fog stream [1¾-inch hose, combination nozzle @ 100 pounds per square inch (psi), 150 gallons per minute (gpm)] and found 2,000 cubic feet/minute (cfm) was introduced into the fire room. Our air-measuring instruments maxed out at this figure, and we conservatively estimate an air flow of 6,000 to 10,000 cfm is moved. For example, you are making an aggressive interior attack on a room-and-contents fire that is 12 × 16 × 8 feet. The volume is 1,536 cubic feet. Using a fog stream, conservatively pushing in 6,000 cubic feet of air in 20 seconds, you have introduced 2,000 cfm of air that has to go somewhere. Air is compressible, becomes overpressurized in front of the stream, and is now directing superheated steam and smoke back on you, despite your ventilation openings. The fog people will tell you it all goes out the vent; try it yourself and see.
We have done this with various size vent holes (up to a full door) in front of the line and still achieved the same result. We coined the term “fog nozzle ricochet” for this phenomenon. Live fire should not be used for this demo; it is too dangerous, even under controlled conditions.
In comparison, try the same experiment with a straight stream off a combination or a solid bore nozzle. You will find the survey tape remains pointing toward the floor under all ventilation conditions, including no vent at all. Certainly, we recommend the standard practice of venting in front of the hoseline, but even in the extreme case of no vent at all during these experiments, a straight stream does not cause the dangerous ricochet that fog does. We measured a maximum air flow of 725 cfm from the straight streams. This volume of air is easily released even through an undersized vent hole.
We conducted numerous experiments in various room sizes and configurations with typical ventilation conditions and have found the wide fog stream always overpressurizes the area in front of the nozzle, driving back air/steam that has been passed through the 2,000°F near the ceiling. Try it for yourself: Operate the fog tip inside, and just watch the tiny drops of water being moved right back toward the nozzleman.
We have done these effective demonstrations at FDIC for the past several years to show the difference between parking lot experience and fire building experience. During these demonstrations, firefighters from across the country were amazed and questioned their use of fog streams for aggressive interior fire attack.
On little drops of water, NIST (1990, “Fire Development in Residential Rooms”) measured temperatures above 2,000°F at the ceiling of typical furnished room fires and shows just how quickly you can make conditions inside deadly, especially during flashover with a fog stream. When the little drops of water ricochet through the superheated air, we use the term “firemen’s soup” to describe conditions caused by misapplication of fog streams inside. It’s not hard to guess who the main ingredient in this deadly mix is.
If this deadly sequence occurs during an aggressive interior fire attack, when things are really bad during a flashover, the last thing I want my nozzleman to do is send a small drop of water up into the superheated atmosphere, convert it to steam, and then use the air currents of the fog stream to stir it all around me and my crew. Consider what will happen if the nozzleman directs that stream over his head and draws fire toward his crew. We recommend, instead of a little drop of water, a large glob of water from a straight stream to penetrate the heat, land on the burning fuel. and extinguish it, permanently reducing flashover potential.
Despite warnings by experts, the American fire service continues not to realize the dangers of using fog inside. William Clark’s landmark book, Firefighting Principles and Practices (Fire Engineering), describes the effects of the fog nozzle and describes the negative pressure near the nozzle caused by the water flowing outward at high velocity. This negative pressure helps draw superheated air toward the nozzle crew when used inside a building.
Chief Lloyd Layman says in his book Attacking and Extinguishing Interior Fires (page 45) about the use of fog inside: “If possible and practical, an indirect attack should be made from positions outside the involved building.” Nowhere in the book published in 1955 does Chief Layman recommend that a firefighter in the same compartment or room use a fog nozzle.
The late Andy Fredericks said, “If you put the fire out, you don’t have to jump out the window.” If you put the fire out, you won’t get caught in a flashover either, making the option of turning the nozzle “left for lobster” moot. The Rockland County Fire Training Center in Pomona, New York, has been conducting flashover training since 1996. During the research for this class, we studied 30 case histories of firefighters who were caught in flashovers and survived, were injured, or were killed. From this limited study group, we concluded that no firefighters were killed or seriously injured when operating an effective hoseline. Like fire prevention, maybe we should be teaching our firefighters flashover recognition and prevention—and proper water application.
The other significant operational fact learned from the live burns in the Swede Survival flashover unit was that when you turn the nozzle to fog at the end of the evolution with the rear doors of the unit wide open, conditions instantly become untenable. This occurs with a fire load of only five sheets of particleboard that at this point in the evolution are mostly burned out. It is reasonable to assume the same will happen in a compartment fire during a flashover producing many times more British thermal units (Btus).
We strongly agree with Walker on the testimonials from a few firefighters who have used the fog stream to cool the room in which they were. This is a crucial point: Do not base your fire attack success or failure on a one-room fire. We have seen one-room fires extinguished with a booster line on a lucky night for certain departments. Once the fire is extinguished (the Btus are gone), the fog line is very effective at cooling the room as a result of the massive air movement it causes. Some departments purchase and use combination nozzles so they can do hydraulic ventilation post-extinguishment. We ask this question: When you buy a ventilation saw, do you ask how many gpm it flows?
It is not 1955, and we should not use 1955 firefighting methods. Hard rubber tires, rubber turnout coats, and wooden aerials are gone forever. Compare and observe the effect of fire streams (without live fire) during an aggressive attack in your training building or an acquired structure, and judge for yourself.
Jerry Knapp
Training Officer
Rockland County Fire Training Center
Pomona, New York
Christopher Flatley
Lieutenant
Fire Department of New York
Tim Pillsworth
Chief
Winona Lake Engine Company
Orange County, New York
Codes and building materials
I am writing to express our disappointment with the article “Modern Building Materials Are Factors in Atlantic City Fires” (May 2010). The article expressed concern that two modern building materials performed poorly in two fires associated with Atlantic City, New Jersey, buildings.
In both cases, the author’s statement that the International Code Council (ICC) had approved these materials is not accurate. The author’s inference that the ICC’s acceptance of these products may not indicate their true potential for fire development also is not completely accurate.
It should be noted that the ICC does not approve building materials. TheInternational Building Code (IBC) clearly assigns the authority to approve building materials to the authority having jurisdiction (AHJ). However, there are code provisions in the IBC that apply to metal composite material (MCM) panels and exterior insulation and finish systems (EIFS). Additionally, ICC Evaluation Service (ICC-ES), a subsidiary of the ICC, has evaluated some MCM panels and EIFS systems for compliance with the provisions of the IBC, to assist AHJs in determining what products to approve for use in their jurisdictions. For more information about this issue, please visit www.icc-es.org/FELetter.
Gary G. Nichols, PE, CBO, SECB
Vice President
ICC Evaluation Service, Inc.
It’s time for national standards and credentials
I’d like to comment on Bobby Halton’s “Professional Qualifications Federal or State Responsibility?” (Editor’s Opinion, November 2010) regarding professional qualifications and whether the federal or state government should be responsible. These comments may be analogous to the smooth bore-fog nozzle debate that may never be resolved. However, discourse is always a good thing.
In a democratic society, governments at any level ideally should only step in when there is “market failure.” I argue that based on the number of firefighter deaths we see every year that we can attribute to poor or wrong training, absent or cursory risk assessments, etc., we have experienced “market failure” and that intervention is necessary.
Sweden experienced a failure in the 1980s, and its government took action to reduce the number of firefighters being killed, directing fire researchers at Lund and other universities to figure out how to fight fires better based on scientific knowledge of fire dynamics and behavior. They then made the training based on that research mandatory and reduced firefighter deaths significantly. Was that endeavor easier for them because it is a smaller country with a nationalized fire service? Absolutely, but that doesn’t mean the U.S. fire service cannot work toward being more homogeneous. While there may be regional differences, we should ask exactly what these differences are. Physics doesn’t change from region to region, so firefighting should be reasonably standardized. If there are some true challenges that are regional, such as the wildland interface issues of the West, those could be addressed separately.
There is already a model in the United States that the fire service could emulate that allows the states to retain a good bit of autonomy while conforming to standards. That is the National Guard. The Army and Air National Guards normally operate under Title 32 of the U.S. Code and serve the governor. They are available for deployment within the state on the governor’s orders for contingencies. However, should the president need those troops, he can federalize them and activate them under Title 10, USC. The kicker here is that the National Guard units must conform to the same standards as their active duty counterparts—same training, same promotion standards, etc., so that there is seamless integration when the boots hit the ground.
I think in the future there are going to be far more situations that will require responses that cross local and state lines than we see now, especially in large urban areas. Departments will have to continue to figure out how to work together seamlessly and be confident in their neighbors. It is time for standards and credentialing that are truly national and portable. Since a change of this magnitude would take at least a generation of firefighters, the time to start is now. The most direct benefit that could come from this and transcend politics is increased safety for firefighters.
Warren Whitley
Assistant Chief, Support Services
Prince William County (VA) Department of Fire & Rescue
Keep oxygen from the fire
I am a sergeant (similar to a U.S. fire service captain) in the Madrid (Spain) Fire Department. I have been a subscriber to Fire Engineering for several years. I would like to comment on the cover of the October 2010 issue.
The caption to the cover photo states: “… members stretch their primary attack line, taking extra time (my italics) to properly flake the line in the front yard ….” It could take three to five minutes for the members to get ready, and the door is OPEN from the beginning of the operation until the attack team begins its job. During that time, the fire is growing inside because it is being fed with oxygen.
In Europe, many fire departments use the tactic “antiventilation.” Its main objective is to cut the supply of oxygen to the fire until the lines are charged and the attack team is ready or to cut the spread of smoke or fire from the origin. This is achieved just by closing a door. This gives us extra time to get ready without feeding the fire. When the attack team is ready, the door is opened, and the conditions inside are reevaluated before entering. This tactic adds to the crew’s safety.
Juan Carlos Campaña López
Madrid Fire Department
Spain
The properties of hydrogen fluoride
In “Electric Substations: Hazards and Response,” on page 74 of the November issue, the authors refer to hydrogen fluoride (HF) gas. I believe that the entry is actually referencing hydrogen sulfide gas. All of the information that I could find about HF gas indicates that it has a pungent odor and doesn’t mention anything about it being an olfactory desensitizer. Instead, the Centers for Disease Control and Prevention information shows it to be irritating to the eyes, nose, and respiratory tract. Hydrogen sulfide gas, on the other hand, does deaden the sense of smell, leading one to believe that the material/threat has dissipated.
Lane A. Sekavec, CHMM
Manager, Hazardous Materials
Union Pacific Railroad
Kansas City, MO
Frank Montagna responds: Lane Sekavec is right. HF alone is not a desensitizer. The article, however, was not speaking specifically to an HF gas response. It was written to provide guidance to firefighters responding to the failure of a high-voltage electrical component using sulfur hexafluoride gas (SF6) and creating a slightly more complicated problem. Thermal decomposition of the gas results in the release of a number of other gases, including several sulfur compounds (see the table below).
Since the article was not intended as a hazmat article, but rather as a heads-up on what can hurt you and how to stay safe during a substation response, we opted to avoid discussing SOF2, SF4, SOF4, SiF4, S2F10, SF5, SO2F2, and SO2, all of which could be present when SF6 thermally decomposes and which would result in desensitizing responders’ olfactory sensors. The firefighters, experiencing a mild exposure to the gas while operating at a high-voltage component failure, could initially suffer only slight respiratory irritation. Within 12 hours, this slight irritation would develop into more significant and possibly life-threatening symptoms. As a result of experiencing only mild symptoms from the HF gas, unprotected firefighters might remain in the contaminated area and suffer a more significant exposure.
The HF gas is lethal and is the most measurable component of the mix. When my coauthor explained the interaction of the gases and electricity to me, I did not see the benefit of going into a detailed chemical explanation but instead opted to keep it simple by explaining how it can hurt responders and what they must do to stay safe.
Sekavec’s background and inquisitiveness picked up what appeared to be a mistake, and I thank him for pointing it out. It was, however, not a mistake, but the result of my decision to make the important information uncomplicated. In my opinion, readers will come away from the article knowing that the thermally decomposed gases can desensitize them and hurt them unless they are properly protected. While, as I said initially, he is right, HF is not a desensitizer. We just did not think the detailed information was appropriate for the intended purpose of the article.
Bravery is also addressing our “hurts”
I am a 47-year public service veteran who is still enjoying the twilight of my career. I have been a volunteer firefighter, an EMT, a part-time police officer, and a paramedic. I’ve served in mid-Michigan and northern Indiana. I’ve logged more than 16,000 calls of one variety or another. I’ve seen the best and the worst that emergencies have to offer. I’m addicted to the business we’re in.
I just read retired Fire Department of New York Robert Senn’s article “Post-Traumatic Stress Disorder: One Firefighter’s Story” in the December issue. It should be mandatory reading for all public service workers—retired, active, or soon to be.
I cannot imagine the mental anguish suffered by our “brothers” on 9/11, as I was not there. It has to equal or surpass the combat stress our brave troops face in many battle activities. We hold ourselves to courage, bravado, and toughness in the face of adversity, but underneath that façade is a fragile, caring, compassionate inner soul that really hurts when bruised. It puts humanity in being human. Oh, we suck it up. We hide it well, but it’s there.
Robert Senn is brave enough to show it and share it with us. He is to be commended for doing so. We can all learn from his experience. Life can be cruel. “It is what it is.” But, we all work it out and, when that alarm sounds, we respond and do it all over again. It’s what we do. Thank you, Brother Senn.
Michael R. Hargreaves Sr.
Firefighter/EMT
Union-Lakeville Fire Territory
Mishawaka, IN
No wall space for terrorists
I could not agree more with Bobby Halton’s “Always Remembered, Always Revered” (Editor’s Opinion, December 2010). It is imperative that our uniformed personnel have their rank appear with their names. Their rank was earned over the many years that spanned their glorious careers. We need to honor them for their achievements in life also. In no way, shape, or form should the terrorists have their own corridor in the same building! Are we going to victimize the families of this tragedy all over again? This museum is to honor the innocent victims that were murdered, and allowing the terrorists any kind of “wall space” in the same building is something that every red-blooded American should be vehemently against!
Scott Shanker
Via Facebook
Thanks to Bobby Halton for his great Editor’s Opinion in the December issue. So many of us lost good friends, mentors, and heroes that day. It’s hard to comprehend how they are being treated today.
Thomas LaBelle
Executive Director
New York State Association of Fire Chiefs
East Schodack, NY
“Always Remembered, Always Revered,” Editor’s Opinion, December 2010, page 8.
Note: The following are updated e-mail addresses for contacting Mr. Joe Daniels and Ms. Alice Greenwald about plans for the 9/11 memorial: joe@national911memorial.org/; agreenwald@sept11mm.org/. The generic address is info@national911memorial.org/.
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