Sunday, April 29, 2018

UL… in 2018


UL… in 2018
  Summer of 2014, and the fire service was buzzing about the latest roll out from ISFSI and their interpretation of the latest UL NIST structure fire studies. A strong emphasis on the benefits of an exterior stream and the subsequent downgrading of traditional interior attack was gaining momentum. You may recall the divisive tone from the modernists and the dinosaur camps. Full disclosure here, you can put me in the latter. For some of us dino’s it wasn’t just the one slicer fits all message but it was the “who” that was presenting the new gospel. That seems harsh I know but street cred (experience) matters. Some were self-describing as experienced fire service leaders but other than an association with training burns, most in the ISFSI roll out crew lacked a history of battling fires from an unscripted plan (sans P. Van Dorp). I realize that not everyone works in an urban/busy fire environment. I don’t either. With my engine going to less than 40 fires a year, I can’t lay any claim to a position of authority, but I will offer my observations anyways. You are reading this right?

 Using people from busy departments brings in street experience and a bit of cynicism which is important to keep these things from turning into an echo chamber. That seems to be what UL NIST did in this most recent round of testing. I applaud everyone involved with these projects as their personal time and reputations where spent.

  The rhetoric was heated and I am sure some personal and professional relationships changed as each camp was looking for their own confirmation via the instruments and a scientific approach. Now that we are all seemingly back in our comfort zones, this latest launch of testing data seems to have gotten a softer response. So, let me go out on a limb here and opine a bit. Hover your mouse over the highlighted words to click the links I am referencing, so you can see where I am coming from.

   In reflection of my 2015 article that was published by Fire Nuggets, I am pleased with this long overdue part 2. Though there will always be more variables to analyze, I think this 3 part series of testing in conjunction to the earlier vertical ventilation study proves, nearly all of the experienced based philosophies that us dino’s know to be true. The concepts I was forwarding in that 2015 article was to clarify that firefighting is done differently for good reasons. Regionally, the circumstances dictate different approaches. The haste to move everyone to either side is foolish. What is not foolish, is to study and understand where experience has proven positive results. A deep dive into the daily operations of your nearest urban fire department may be a good starting point for a younger or light duty fire department.

      With the latest information from UL published, I see another Fire Service Essentials book update in the future!! As I interpret the 3 recent parts that have been published, here are some practises that have proven themselves in the streets and now in a lab.

1.  When faced with a residential building fire only showing smoke, the most efficient practice is to launch an interior attack.
2.  Water up into smoke is useful to map the room. Nozzle teams should use the reach of the stream to cool the walls and ceiling surfaces thus rapidly cooling the off gassing interior surfaces.
3.      The practical patterns of stream delivery are to start at a very steep angle and evolve into an “O”, “T”, “Z”, or “n” pattern. Water runs from the ceiling out to the walls.
4.      Rollover must be met with an overwhelming water. Longer flow times are better than short bursts.
5.      While not all fires are the same, there are many similarities. The variables are the circumstances surrounding the extinguishing crew, training, equipment, and experience.
6.      Air entrainment studies confirm earlier testing and investigation. Thank you Jerry Knapp.
7.      Air tracks are directly affected by a flowing nozzle. You push air with your water.
8.  Steam and gas burns were linked to proximity to the fire area, the flow path, and the elevation within the building. If you are above the fire or in its path, you or trapped civilians may burn.
9.      Flowing while moving did show an advantage in gaining and maintaining better air quality and lowering temperatures. The flow/shutdown/move/flow tactic is still the most likely method of attack, and the thermal measurements within the approach hallways proved that this works well as long as there is no delay in moving in on the fire.
10. Realistic flow rates were used and proved valuable in qualifying why we should take more water than we expect to use. Its gallons per minute, not total gallons used. Rate of application matters, and the total amount of water needed for each of these tests was less than 500 gallons.

     The amount of effort given in this publication to study steam and energy transfer is a great resource. Read that carefully. The moister content of smoke is much, much greater than I had thought was possible. The 1 thing I had hoped for was a more careful measurement of the moister in the air during suppression efforts, and at more than the 1 foot level from the floor. Perhaps the limiting factor was the technology of the instruments? Either way, this is great information and supports the idea of cutting off the smoke and fire from occupants and using a coordinated attack.
   The air entrainment study was a welcomed read as well. If you have not read Jerry Knapp’s older studies and tests from 2003, then this write up may have been news to you. In fact, the reference section of the air entrainment document tells the story. This is another testament that the modern fire science is qualifying what we have already had available to us.

   The water mapping study was interesting but not all that surprising. When you have been on a company that had switched from high pressure automatic nozzles to low pressure nozzles, you know firsthand that you are using less water overall. The rate of application is always better in the real world with high volume /low pressure nozzles because we as a service pump to comfort. Water adhesion is documented where streams directed at the ceiling cling to the surface and run out to the walls. The water then runs down the walls cooling the surfaces and thus reducing the off gassing. “Wall-ceiling-wall!” – Jeff Shupe    If I had a dollar for every time I heard that as a new cadet/recruit!

   The ongoing conversation has indirectly or directly pushed the testing and analysis of interior firefighting in a direction so as to prove or disprove what each side believed to be true. The main difference was between the traditionalist using decades of experience versus the modernists approach with recent (though incomplete) data and sterile examples. It seemed clear that the initial exterior application of water was the tactic of choice by those paid to roll out the data to the fire service. This is a result of those tests having a narrow focus on that tactic and that detail to me, seemed to be the problem with our collective understanding. It didn’t help that the initial verbiage and intent of the ISFSI was clearly pushing this tactic as “SLICE is a fire attack mode tactic used to reduce temperatures inside of a building prior to the entry by firefighters for extinguishment or rescue.”  The urban dinosaurs reply with “we have always done this when needed”. It is the when needed part that is variable and department dependent. Some dino’s cited the previous book smart non-sense of “trying to attack from the unburned side” not too long ago. And thought that hard from the yard mantra would pass like the rest of the fads.

  As the last 2 years went by, the tone on both sides relaxed. The dinosaurs could recognize where an understaffed department with limited experience would be happy to adopt this tactic, as it is seemingly a “safer operation” for arriving firefighters. In addition, the YouTube channels and fire behavior websites where produced with folks from non-urban departments. Those without the decades of building fires under their belts, pointed to the instrument data and the argument of “we don’t have 30 firefighters at a house fire”. Though, all you need is 3 dedicated and trained firefighters to get any attack hose line in place!

  Regardless, all 50 state fire school curriculum's adopted the “transitional attack” without having all of the interior stream data to weigh against it. The money ball was rolling, and the essentials book writers had another reason to roll out a new edition. Fire schools everywhere were rushing to adopt this tactic at the basic level and the dumbing down of the fire academy was on. For safety reasons of course. Young cadets did not have the advantage of their own experiences or their 1st due staffing levels, in relation to using an acronym.  At nausea we all refer to this now as “another tool in the tool box”. But I would suggest that most un tested fire department’s tool boxes only have hammers in them, or pre-connected lines as it were. Fire chiefs who were looking out for their liability interests, adopted the ISFSI KOOL-AID without regard to the legitimate debate. When any movement gets to the political momentum like slicers did, the discussion and debate is done.

   To further this issue in the wrong direction many states including Ohio, adopted the IFSAC or PRO BOARD curriculum's which replaces area norms with unrealistic minimum standards. Go ahead and click the link and check out those qualification minimums… These private for profit curriculum development companies sell their wares so any card carrier can be employable by multiple states. And many have had their curriculum's codified so as to be state law! This one size fits all, or as I like to call it “Common core for the fire service” glosses over many regionally specific needs and eliminates the time allowed for instructors to pass on experienced based information to the cadets. The argument for a science proven tactic or “hitting hard for the yard” was and is, firmly in place for the young and impressionable cadets. Personally, I just couldn’t be a part of this agenda, and left what was a very enjoyable and fulfilling position as an academy instructor. At this point I am confident that my previous fire school has found a way to teach around these mandates, but the fact remains that if a cadet does the state minimum, they get a fire card that looks just like mine, but a tuition bill from the community college that’s quite a bit more.

   So now what? I suggest training in as a realistic environment as possible, and keeping true to the regional/area specific needs. Whether it be in stand pipes or silos. Basements or mid rises. Garden apartments or Mc mansions. Type 3 ordinary or tilt ups. Giant type 2 distribution centers or sprawling mass assembly buildings. Taking this information from UL/NIST and applying it to your department’s unique level of staffing, equipment and operations should be considered purposefully.

 Additionally, you may or may not know that the DHS grants that make these things possible are only approved with a teaching component. That is where the interpretation of the raw information is made. And that is where the information may be applied differently to different fire departments. In Chicago “Hard from the yard” means deck-gunning multi-story tenements because the stand pipe is out of service, but in Hanover fire district Virginia, it doesn’t. So you must decide how this information fits your area. The principles of firefighting remain consistent. The way your organization practises these is the difference. Before you go and drink anyone else’s kool-aid, be sure yours isn’t all that bad.

   Lastly, the ripple effect and some push back has re energized the fire service in both looking at what has worked in the past, and the future technologies that can help us do our jobs more efficiently. In that regard, the evolution of fire service training is also happening. More and more regional fire conferences are taking root. Small towns, suburban cities and metro areas are developing groups of firefighters interested in the practice of the principles. Staying away from PowerPoint classes with certificates, these smaller venues are about breaking a sweat and doing the job. And for that I am grateful. The decentralization of fire training is a good thing. No more is the influence of the “gate keepers” of the industry so complete. If you look around there is a reasonably priced 2 day conference somewhere closer than Indianapolis. The big show has its place but the regional training is as legitimate as it can get. I hope I set off a brush fire in your head with this. If you agree with some or none of it, I just hope you know why that is from personal experience, rather than someone else’s.

Friday, March 9, 2018

Essentials? Rewriting the book of firefighting over the years.

Essentials of Fire Fighting, First Edition (IFSTA, 1977)
Chapter 6 Fire Streams, Pages 174-176
Requirements For Extinguishing Structural Fires
Building fires may be divided into fires which are primarily confined within the walls, roof, and floor of a structure or building, and fires within a building which have ventilated
themselves to the extent that they are free burning into the open. Each of these conditions presents a different problem and fire fighting situation.
When fire is confined within the walls, ceiling, and/or roof of a room or building, the intense heat, smoke, and fire gases will also be confined in the burning space. The confined
building fire presents a situation that requires careful consideration to prevent further damage and to effect extinguishment. This type of fire may be considered in three different
phases for the purpose of deterring requirements. First, the Incipient or Beginning Phase; Second, the Free-Burning Phase; and Third, the Smoldering Phase. The major
difference between the three phases is from the standpoint of ventilation practices. Knowledge of these phases is also useful from a fire extinguishment point of view.
A fire in the incipient phase usually requires a direct application of water at the base of the fire to reduce the temperature of the fuel below ignition point. The amount of heat being
generated will increase as the fire progresses. Although the flame temperature will be well over 1,000 degrees Fahrenheit, the room temperature may only be slightly increased.
The major consideration is reaching the fire.
In the second phase or free-burning phase, the area will be extremely hot. A confined building fire in the second phase required a reduction of atmospheric temperature to livable
conditions so that firefighters may enter and extinguish any remaining fires by direct application but protective breathing equipment will be required for the safety of those
entering.
In the third or smoldering phase, the heated area will be filled with hot smoke and fire gases. So far as the fire gases and smoke are concerned, firefighters could enter with
protective breathing equipment, but the heat would be unbearable. Experiments and tests have shown that a building containing a third phase fire may be made tenable by
applying water fog into the most highly heated upper levels. The heat will convert the finely divided particles of water into steam thereby reducing the temperature in the space.
The expansion of steam will further force smoke and gases from the space. In this phase, the heat must be reduced, and the smoke and gases must be displaced before fresh air
can be admitted.
An open or non confined building fire is one which has burned to the outside, releasing the heated smoke and gases. The entire building may be involved and these open fires
require long-range operations. The intense radiated heat from an open fire makes it difficult to apply water directly at the base of the fire. A large volume of water is usually
required to control and extinguish this type fire, which may require straight streams and long-range fog streams. This type of fire also requires careful consideration of exposures,
with equal consideration for fire streams to protect them
A Confined Strutural Fire
The conditions that may be found in a confined structural fire and the phases of its development have again been outlined by the Analysis Table, from which we may list the
important factors of applying fog streams. Some of these important factors are as follows:
• The fog stream should be projected into the hottest space, which may be the upper levels if the fire has burned for a considerable duration.
• If a short-reach, wide-angle fog pattern will cover the area, it should be projected upward into the heated area and worked into a circular motion for complete coverage.
• If the area is so large that it cannot be reached by the short-reach, wide-angle fog pattern, a long-reach fog pattern should be used to carry the droplets into the hottest space
and the nozzle worked back and forth for complete coverage.
• The number of fog streams to use should be determined by the cubic foot area involved and the volume of the nozzles.
• Enough water fog must be applied to absorb the heat faster than it is being generated.
• One or more extra lines should be supplied for auxiliary use. They may be used to extinguish remaining fire.
• The officer in charge should watch for displacement indications: first, smoke; second, smoke and condensed steam; and third, condensed steam.
• A fog stream should but shut off as soon as smoke and gas have been displaced by condensed steam.
• If the atmosphere is still too hot, a second burst of water fog may be required.
• All spot fires may be extinguished by direct application.
• When the application of water fog is made through an opening into a building, the firefighters should keep well out of line with the opening to protect themselves from the
expulsion of heated gases and steam back through the opening.
Essentials of Fire Fighting, Second Edition (IFSTA, 1983)
Chapter 14 Fire Suppression Techniques, Pages 340-341
(RED INDICATES CHANGES FROM FIRST EDITION)


Direct Attack
The most efficient use of water on freeburning fires is made by a direct attack from a close position with a solid stream or penetrating fog pattern (30 degree or less) on the base
of the fire. The water should be applied directly on the burning fuels in short bursts until the fire “darkens down”. Streams should not be applied for too long a time or the thermal
balance will be upset. Thermal balance is the movement of heated gases toward the ceiling and after the application of fire streams that includes the spread of expanding steam
to all areas of the confined space. If water streams are applied for an excessive length of time, the steam begins to condense causing the smoke to drop rapidly to the floor and
move sluggishly thereafter.
Indirect Attack
When firefighters are unable to enter the structure due to intense conditions in confined locations, an indirect attack can be made (Figure 14.2). This attack is not desirable where
victims may yet be trapped or where the spread of fire to uninvolved areas cannot be contained. The nozzle flow setting will range from a penetrating fog (30 degree) to moderate
angle fog (60 degree) and should be directed at the ceiling and played back and forth in the super heated gases at the ceiling level. Directing the stream into the superheated
atmosphere near the ceiling results in the production of large quantities of steam. One cubic foot of water (7.4 gallons) completely vaporized will create 1700 cubic feet of steam.
Once again, the stream should be shut down before disturbing the thermal balance. Once the fire has been darkened down the hose line can be advanced to extinguish any
remaining hot spots with a direct attack.
Combination Attack
The combination method utilizes the steam generating technique of ceiling level attack with an attack on materials burning near the floor level. The nozzle may be moved in a, “T,
Z, or O” pattern starting with a penetrating fog directed into the heated gases at the ceiling level and then dropped down to attack the combustibles burning near the floor level.
The “O” pattern of the combination attack is probably the most familiar and abused method of attack. When performing the “O” pattern the stream should be directed at the ceiling
and rotated clockwise with the stream edge reaching the ceiling , wall, floor, and opposite wall. Keep in mind that applying water to smoke does not extinguish the fire and only
causes unnecessary water damage and disturbance of the thermal balance.
Essentials of Fire Fighting, Third Edition (IFSTA, 1992)
Chapter 12 Fire Control, Pages 404-406
(RED INDICATES CHANGES FROM SECOND EDITION)


Direct Attack
The most efficient use of water on freeburning fires is made by a direct attack from a close position with a solid stream or
penetrating fog pattern (30 degree or less) on the base of the fire straight stream. The water should be applied in short bursts
directly on the burning fuels in short bursts until the fire “darkens down” (Figure 12.10). Streams Water should not be applied for
too long a time or the thermal balance layering (movement of heated gases toward the ceiling) will be upset. Thermal balance is
the movement of heated gases toward the ceiling and after the application of fire streams that includes the spread of expanding
steam to all areas of the confined space. If water streams are is applied for an excessive length of time, the steam begins to
condense causing the smoke to drop rapidly to the floor and move sluggishly thereafter.
Indirect Attack
When firefighters are unable to enter the structure or fire area due to intense fire conditions in confined locations, an indirect
attack can be made (Figure 12.11). This attack is not desirable where victims may yet be trapped or where the spread of fire to
uninvolved areas cannot be contained. The fire stream, which could be a solid , straight, or narrow fog pattern, The nozzle flow
setting will range from a penetrating fog (30 degree) to moderate angle fog (60 degree) and should be directed at the ceiling and
played back and forth in the super heated gases at the ceiling level. Directing the stream into the superheated atmosphere near
the ceiling results in the production of large quantities of steam. One cubic foot of water (7.4 gallons) completely vaporized will
create 1,700 cubic feet of steam. Once again, the stream should be shut down before disturbing it disturbs the thermal balance
layering. Once the fire has been darkened down, and the space has been ventilated, the hoseline can be advanced to extinguish
any remaining hot spots with a direct attack.
Combination Attack
The combination method utilizes uses the steam-generating technique of ceiling level attack combined with an attack on
materials burning near the floor level (Figure 12.12). The nozzle may be moved in a, “T, Z, or O” pattern starting with a solid,
straight, or penetrating fog directed into the heated gases at the ceiling level and then dropped down to attack the combustibles
burning near the floor level. The “O” pattern of the combination attack is probably the most familiar and abused method of attack.
When performing the “O” pattern, the stream should be directed at the ceiling and rotated clockwise with the stream edge
reaching the ceiling , wall, floor, and opposite wall. Firefighters should keep in mind that applying water to smoke does not
extinguish the fire and only causes unnecessary water damage and disturbance of the thermal balance layering.
Essentials of Fire Fighting, Fifth Edition (IFSTA, 2008)
Chapter 15 Fire Control, Pages 767-769
(RED INDICATES CHANGES FROM FOURTH EDITION)


Gas Cooling
Gas cooling is not a fire extinguishment method but simply a way of reducing the hazard
presented by the hot gas layer. This technique is effective when faced with a shielded fire;
that is, one you cannot see from the doorway because objects are shielding it. In these
situations, you cannot apply water directly onto the burning material without entering the
room and working under the hot gas layer.
The hot gas layer accumulating in the upper levels of the compartment can present a
number of problems for you and other members of the hose team. Remember that smoke
is fuel, and it may transition to rollover, flashover or a smoke explosion at any time. In
addition, hot smoke radiates heat to furniture and other combustibles in the compartment.
This increases pyrolysis which adds more flammable fuel to the gas layer. Cooling the hot
gas layer mitigates these hazards by slowing the transfer of heat to other combustibles
and reducing the chances of the overhead gases igniting.
You can cool the hot gas layer by applying short pulses of water for into it. With the nozzle
set on a 40- to 60- degree fog pattern, direct it upward toward the gas layer and quickly
open and close it in one- to two second pulses (Figure 15.11). Remember that your intent
is to cool the gases, not to produce a large volume of steam. When water droplets begin
to fall out of the overhead smoke layer, it means that the gases have been cooled and
you can stop spraying water into the smoke. If the fire continues to burn unchecked, the
gas layer will regain its heat and the gas-cooling technique may have to be repeated.
The gas-cooling technique should be repeated as necessary while the hose team
advances under the gas layer toward the fire. In narrow hallways, the fog pattern may
need to be restricted. In large-volume compartments, the duration of the pulses may need
to be increased slightly.
Direct Attack
The most efficient use of water on free-burning fires is made by a direct attack on the
base of the fire - usually from with a solid stream or straight stream. The water should be
is applied in short bursts directly onto the burning fuels (often called “penciling”) until the
fire “darkens down” (Figure 15.12). Another effective technique (often called “painting”) is
to cool hot surfaces to slow or stop the pyrolysis process by gently applying water and
allowing it to run over the hot material. Water should not be applied for too long a time
otherwise thermal layering will be upset long enough to upset the thermal layering
(sometimes called thermal balance); the steam produced will begin to condense, causing
the smoke to drop rapidly to the floor and move sluggishly thereafter.
Essentials of Fire Fighting, Fifth Edition (IFSTA, 2008)
Chapter 15 Fire Control, Pages 767-769
(RED INDICATES CHANGES FROM FOURTH EDITION)
2008


Indirect Attack
When firefighters are unable to enter the structure or fire area due to a burning building or compartment because
of the intense fire conditions heat inside, an indirect attack can be made from outside the area compartment
through a doorway or window or other small opening (Figure 15.13). This method of attack is not desirable ideal
where victims building occupants may yet be trapped still be inside or where the spread of fire to uninvolved
areas cannot be contained. However, this may be the only method of attack possible until temperatures are
reduced. The fire stream, which could be a solid , straight, or narrow fog pattern, should be directed at the
ceiling and played back and forth in the superheated gases at the ceiling level.
To make an indirect attack on the fire, a fog stream is introduced through a small opening and directed at the
ceiling where the heat is the most intense. Directing the stream into the superheated atmosphere near the ceiling
results in the production of large quantities of steam, but the stream should be shut down before it disturbs the
thermal layering. The heat converts the water spray to steam, which fills the compartment and absorbs the bulk
of the heat. Once the fire has been darkened down and the space has been ventilated, the hose-lines can be
advanced to extinguish any remaining hot spots with a direct attack and water applied directly onto whatever is
burning.
Combination Attack
The combination attack method uses the heat-absorbing steam-generating technique of ceiling-level attack
cooling the hot gas layer combined followed by a heat-reducing with a direct attack on the materials burning near
the floor level. The attack starts with short bursts, known as penciling, from nozzle may be moved in a, T, Z, or O
pattern starting with a solid, straight, or a penetrating fog stream directed into the hot gas layer heated gases at
the ceiling level (gas cooling) (Figure 15.14). and then dropped down Then the attack switches to a straight
stream, known as painting, to attack the combustibles burning near the floor level. The O pattern of the
combination attack is probably the most familiar method of attack. When performing the O pattern, the stream
should be directed at the ceiling and rotated with the stream edge reaching the ceiling, wall, floor, and opposite
wall. Firefighters should keep in mind Remember that applying water to smoke does not extinguish the fire and
only causes unnecessary water damage and disturbance of the thermal layering
Essentials of Fire Fighting, Sixth Edition (IFSTA, 2013)
Chapter 17 Fire Control, Pages 1013-1016
(RED INDICATES CHANGES FROM FIFTH EDITION)


Direct Attack
The A direct attack on the fire using a solid or straight uses water most efficiently use of water
on free-burning fires (Figure 17.8) is made by a direct attack on the fire - usually from a solid
stream or straight stream. The water is applied in short bursts directly onto the burning fuels
(often called “penciling”) until the fire is extinguished “darkens down” (Figure 15.12). Another
effective technique (often called “painting”) is to direct the stream onto the ceiling and walls
cool hot surfaces which can to slow or stop the pyrolysis process on these hot surfaces by
gently applying water and allowing it to run over the hot material. Water should not be applied
long enough to upset the thermal layering (sometimes called thermal balance) in the
compartment; the steam produced will begin to condense, causing the smoke and heat to drop
rapidly to the floor and move sluggishly thereafter.
Indirect Attack
When firefighters are unable to enter a burning building or compartment because of the intense
heat inside, an indirect attack can be made from outside the structure or involved area
compartment through a window or other small opening (Figure 15.13). The attack is made
through a window or other opening, directing the stream toward the ceiling to cool the room
(Figure 17.9). This method of attack produces large quantities of steam and must be
coordinated with ventilation. is not ideal where building occupants may still be inside or where
the spread of fire to uninvolved areas cannot be contained. While an indirect attack cools the
fire environment, it results in a fairly uniform temperature from floor to ceiling and fills the
compartment with the combined mixture of smoke and steam. However, this may be the only
method of attack possible until temperatures are reduced.
To make an indirect attack on the fire, a fog stream is introduced through an small opening and
directed at the ceiling where the temperature is the highest heat is the most intense. The heat
converts the water spray to steam, which fills the compartment and absorbs the majority bulk of
the heat. Once the majority of the fire has been reduced in quantity darkened down and the
space has been ventilated, hoselines can be advanced inside and firefighters can make a
direct attack on the body of fire water applied directly onto whatever is burning.
Essentials of Fire Fighting, Sixth Edition (IFSTA, 2013)
Chapter 17 Fire Control, Pages 1013-1016
(RED INDICATES CHANGES FROM FIFTH EDITION)


Combination Attack
The combination attack uses the heat-absorbing technique of combines cooling the hot gas layer at the
ceiling level using an indirect attack with a followed by a heat-reducing direct attack on the materials fuels
burning near the floor level. The attack starts with short bursts, known as penciling, from a penetrating fog
stream directed into the hot gas layer at the ceiling level (gas cooling) (Figure 15.14). Then the attack
switches to a straight stream, known as painting, to attack the combustibles burning near the floor level.
To combine both attacks, move the nozzle from the area overhead to the floor in a Z, inverted T, or
rotational manner (Figure 17.10) Remember that applying Excessive application of water to smoke does
not extinguish the fire and only may causes unnecessary water damage and disturbance of the thermal
layering. Applying water to smoke that is not heated may disrupt the thermal layering which has a
tendency to decrease visibility if ventilation is not accomplished.
Gas Cooling
Gas cooling is not a fire extinguishment method but simply is a way of reducing the hazard presented by
heat release from the hot gas layer. This technique is effective when faced with a shielded fire; that is,
one you cannot see from the doorway because it is located in a remote part of the structure or objects are
shielding it the fire . In these situations, you cannot apply water directly onto the burning material without
entering the room and working under the hot gas layer.
The hot gas layer accumulating in the upper levels of the compartment can present a number of problems
for you and other members of the hoseline team crew. Remember that smoke is fuel, and it may transition
to rollover, flashover or a smoke explosion at any time. In addition, hot smoke radiates heat to furniture
and other combustibles in the compartment. This increases pyrolysis which adds more flammable fuel to
the gas layer. Cooling the hot gas layer mitigates these hazards by slowing slows the transfer of heat to
other combustibles and reducing reduces the chances of the overhead gases igniting.
You can To cool the hot gas layer, direct short bursts or by applying short pulses of water for into it. With
the nozzle set on a 40- to 60- degree fog pattern, direct it upward toward the gas layer and quickly and
smoothly open and close it in one- to two second pulses (Figure 17.11). The length of the pulse will
depend on the size of the space, varying from less than a second to much longer. The nozzle pattern may
need to be adjusted based on fire conditions in the compartment and its configuration and size. In narrow
hallways, the fog pattern may need to be restricted. In large-volume compartments or when the upper
layer temperature is extremely high, the duration of the pulses may need to be increased slightly.
The reach of the stream is also important for cooling the gas layer. Remember that Your intent is to cool
the gases, not to cool the ceiling produce a large volume of steam. Cooling the ceiling will produce a
large volume of steam. When If water droplets begin to fall out of the overhead smoke layer, it means that
the gases have been cooled and you can stop spraying water into the smoke. If the fire continues to burn
unchecked, the gas layer will regain its heat and the gas-cooling technique may have to be repeated.
The gas-cooling technique should be repeated as necessary while the hose team advances under the
gas layer toward the fire.
Essentials of Fire Fighting, Sixth Edition (IFSTA, 2013)
Chapter 17 Fire Control, Pages 1013-1016
(RED INDICATES CHANGES FROM FIFTH EDITION)
2013