Which nozzle for fashover?

Replies to This Discussion

Permalink Reply by Dave Clark on July 1, 2009 at 1:39pm

Hey all,
I have heard some really great discussion on the subject of nozzle choice on flash-over, and can only surmise that there are some unresolved issues here which could cost some skin or life. I'm a west-coasty with three man companies and the old school combi nozzles or worse break-aparts. Our training comes mostly from the east coast experience, but takes a while to finally reach way out here on the fronteer. It seems that most agree that a smooth bore is the way to go if your fighting fire in a structure, which is also where flashovers ocurr. Puting enough water on the fire on the way in, and then if things go south in a hurry put more water before a flash. BUT my real question is this:

Why are you there? Did you actually do a size-up or just cowboy in the door ready to risk it all on this fire? Is there anyone inside near the fire who could survive the current heat and smoke conditions? Is the vent team in place before you decided to orphan your children for a structure the insurance company is already writing the check to replace?

The very best tool to use in a flash-over situation is between your ears! Don't put yourself into that situation. Use the experience of yourself and others to teach you when it is getting too hot, cool down the upper-levels with a smooth bore, ASK for the proper ventillation, and have an exit strategy which can be put into action within seconds. Never replace common sense with ego. Risk LIFE to SAVE LIFE. The best fire stories are the ones you tell yourself!

Permalink Reply by Walter J Lewis on July 1, 2009 at 5:28pm

Why are you getting "deep in the heat" with an 1 3/4"? Many fire service educators have been preaching for years, and for good reason, the addage of not opening up on smoke is old-news. Black fire, a pretty good precursor to flashover, is nearly as bad and if not prevented, slowed or stopped, will over-run you. If you end up in a burn unit or a coffin with a working nozzle in your hands, attached to a properly flowed line, then shame on you. Long discussion can occur about Automatic nozzles and their hazards, but I'm talking about a properly working smooth bore or straight stream nozzle. If you need to open up, then OPEN UP!

If you don't know why NOT to use "left for life", put a lid on a pot of water. Let the water get to a boil. Remove the lid. Put your hand over the pot of water. See how much you want to stay there. If you don't feel anything, have yourself checked by a doctor. In this case, the water's only at 212 degrees. Increase it's temperature by sending it to hotter temps at ceiling level, let physics happen and what your doing is terrible. For you, your crew and anyone else within.

It fathoms me how this is still a considerable option in the American Fire Service. WE AREN"T SWEDISH! We go into the structures to search for occupants. Pulsing the fire pushes back vapor fire coming at you. Nice. However, sometimes there is more to the vapor fire than what will be controlled by the pulse. Attack the seat of the fire. It's dark, its scary- I know. It's possible. And in many cases necessary- our citizens expect us to do our job. Especially if they are trapped in the same environment without protection.

Remember the reason why we show up. To save lives and protect property.

Permalink Reply by Walter J Lewis on July 1, 2009 at 5:33pm

Bro- that seems like a terrible idea. What if you accidentally turn the nozzle so that the fog comes out also and you didn't want it to, as if you were crawling in with the line? Does the nozzle lend itself to doing that? Does it push the fire pretty well, as a fog would? Do you guys use it for interiro work, or exterior firefighting (wildland, car fires) where the fog would be helpful in radiant heat protection?

Please don't take this as bashing, I'm honestly curious. I'd like to try it for myself at the academy.

Brandon Krause said:

We use the combi-pok smoothbore nozzles, they have a sliding collar the when pulled back creates an impenging stream full fog pattern. This is set up as a protection system and with it not being at typical type fog it doesnt seem to move as much air. Might cut down on pulling the fire in? One question I ask to Scott is do you wear the HFD Reed hood?


http://www.edarley.com/finditem/20923

Permalink Reply by Mike Walker on July 2, 2009 at 12:12pm

Bigger then the one on that line. Why? One to put out a fire that was obviously too big for the line I took in, and two to wash the s*** out of my pants when I get out.

Permalink Reply by Jim Miller on July 3, 2009 at 9:53am

It sounds as if you are trying to play two cards.I am there to protect life and save property!!!! I am there to stretch, staff, and advance a line between the victims and the fire and to protect any property that is deemed savable. Therefore, if the fire is doable, then you have to do what you are sworn to do, put the fire out. Therefore, sooner or later you are going to have to determine when to open the nozzle, you know to make the push, prevent imminent flashover, make the fire room and extinguish. Size-up is important, but you can't see it all from the outside or fight them all from the window. A room and contents fire out into the hall has the potential for flashing. This you have to determine from the HALL! Anyway, flashover recognition and control is vital, because just because you entered don't make you a cowboy.

Dave Clark said:

Hey all,
I have heard some really great discussion on the subject of nozzle choice on flash-over, and can only surmise that there are some unresolved issues here which could cost some skin or life. I'm a west-coasty with three man companies and the old school combi nozzles or worse break-aparts. Our training comes mostly from the east coast experience, but takes a while to finally reach way out here on the fronteer. It seems that most agree that a smooth bore is the way to go if your fighting fire in a structure, which is also where flashovers ocurr. Puting enough water on the fire on the way in, and then if things go south in a hurry put more water before a flash. BUT my real question is this:

Why are you there? Did you actually do a size-up or just cowboy in the door ready to risk it all on this fire? Is there anyone inside near the fire who could survive the current heat and smoke conditions? Is the vent team in place before you decided to orphan your children for a structure the insurance company is already writing the check to replace?

The very best tool to use in a flash-over situation is between your ears! Don't put yourself into that situation. Use the experience of yourself and others to teach you when it is getting too hot, cool down the upper-levels with a smooth bore, ASK for the proper ventillation, and have an exit strategy which can be put into action within seconds. Never replace common sense with ego. Risk LIFE to SAVE LIFE. The best fire stories are the ones you tell yourself!

Permalink Reply by Brandon Krause on July 3, 2009 at 8:52pm

The fog portion only slides with some force, I have never seen one open accidentally! None of our guys have ever used the fog outside of training just to see what it looks like. We use this style of nozzle on all lines even the 2 1/2". We will probably not be ordering anymore, going to smoothbore tip and shutoff only.

Walter J Lewis said:

Bro- that seems like a terrible idea. What if you accidentally turn the nozzle so that the fog comes out also and you didn't want it to, as if you were crawling in with the line? Does the nozzle lend itself to doing that? Does it push the fire pretty well, as a fog would? Do you guys use it for interiro work, or exterior firefighting (wildland, car fires) where the fog would be helpful in radiant heat protection?

Please don't take this as bashing, I'm honestly curious. I'd like to try it for myself at the academy.

Brandon Krause said:

We use the combi-pok smoothbore nozzles, they have a sliding collar the when pulled back creates an impenging stream full fog pattern. This is set up as a protection system and with it not being at typical type fog it doesnt seem to move as much air. Might cut down on pulling the fire in? One question I ask to Scott is do you wear the HFD Reed hood?


http://www.edarley.com/finditem/20923

Permalink Reply by Ed Hartin on July 5, 2009 at 1:10pm

While there appears to be a great deal of agreement among the responses to the original post which asked: “Suppose you are "deep in the heat" on a 1 3/4" when things go awry (flash or near-flash). Which nozzle do you want on your line and why?”

All of the responses to this point advocate high flow, solid (or at least straight) stream application to counter impending flashover conditions. Reasons identified include the need for a high flow rate as well as lower steam production and reduced impact on air flow to the fire. I take a different position. A combination nozzle (with an adequate flow rate) allows effective cooling of the hot gas layer with a fog pattern and effective direct attack with a straight stream. The best way to deal with potential flashover conditions is to prevent them from developing. This requires knowledge of fire behavior, situational awareness, and effective tactical operations.

Stating, “apply the right amount of water in the right place during the right time span” George Potter paraphrased made by Floyd Nelson in his book Qualitative Fire Behavior, Nelson continued on to say “However, the number of different fire situations one finds in structures often makes this task difficult” (p. 102). This is absolutely correct.

While steam production is often cited as a hazardous consequence of using a fog pattern during interior firefighting operations, water that has not been converted to steam has not done significant work towards fire control. The energy required to raise the temperature of water (and correspondingly reduce the temperature of hot gases or surfaces) is considerably less than that required to turn water at 100o C (212o F) into steam. For example, raising the temperature of one kilogram (kg) of water from 20o C (68o F) to 100o C requires 334.88 Kilojoules (kJ) of energy, the energy required to change the same kilo of water to steam requires 2260 kJ of energy (almost seven times the energy required to heat the water to its boiling point). Steam is not the problem, excessive steam production is.

Solid or straight streams are generally the most effective way to apply cooling water to burning fuel. However, they are not particularly effective at cooling hot gases. Firefighters generally understand the concept of surface to mass ratio when applied to fuel (lightweight trusses in comparison to heavy timber or a Christmas tree compared to a log of the same mass). The same concept applied to water used for fire control. Small droplets have a greater surface area in comparison to their mass. This makes for less reach, but tremendous capacity for cooling hot gases.

If water can be applied directly to the burning fuel you can put the fire out and solve the problem. However, what if the fire is shielded from direct attack? Flashover requires transfer of sufficient energy to fuel packages (such as furniture or combustible compartment linings) to result in rapid transition to flaming combustion. Cooling the hot gas layer reduces heat transfer to unburned fuel and the thermal insult to firefighters below the hot gas layer. This reduces the potential for flashover and increases the safety of the hose team pushing in to the seat of the fire.

Excess steam production does not result from the use of a fog pattern, but from inappropriate use of water fog. Water expands considerably when converted to steam. However, cooling the hot gases overhead causes them to contract. Water turned to steam in the hot gas layer causes a greater contraction in the hot gas layer than the expansion of steam, actually reducing the total volume of hot gases overhead and potentially raising the level of the hot gas layer. While this is a (relatively) simple application of the Ideal Gas Law, it is contrary to most firefighter’s experience. Why? The answer is simple.

Water that does not turn to steam in the hot gas layer hits the ceiling where it turns to steam and expands (roughly 1700:1 at 100o C) and adds to the volume of the hot gas layer. If excessive water reaches the ceiling or other hot compartment linings, the volume of the hot gas layer will increase an cause the level of the hot gas layer to drop, making conditions uncomfortable at best and untenable at worst. Long application or use of an ineffective pattern (too narrow or too wide) can result in too much water reaching compartment linings and resulting excess steam production.

As Floyd Nelson observed, the solution is to put the right amount of water in the right place. Cooling hot gases to manage the fire environment is most effectively accomplished with a (relatively) small amount of water applied in a fog pattern. However, this is not an extinguishing technique. It is simply a method to reduce the temperature of the hot gas layer and the potential for extreme fire behavior. Use of a straight or solid stream in an effort to cool gases is considerably less effective and is likely to result in production of excessive steam (as water will be converted to steam on contact with the compartment linings rather than hot gases).

Developing the skills necessary for effective fire stream application requires practice. I concur with the posts that point to limitations of container based props. However, it is important to remember that all live fire training is a simulation. Container based props are an excellent tool when used correctly and provide a great opportunity for participants to observe fire development in a compartment and learn nozzle technique. However, they have as much to do with firefighting as a driving range or putting green have to do with the game of golf. Useful tools for deliberate practice, but not the same thing! As observed by earlier replies, the instructor is the key to providing participants with an understanding of the context and purpose of the training exercise.

Ed Hartin, MS, EFO, MIFireE, CFO
CFBT-US, LLC
http://www.cfbt-us.com

Permalink Reply by Stephen Florian on July 11, 2009 at 11:56pm

I do agree with what ever nozzle works and has water, but also remember this dont put your self into this situation unless someones life is in jeapordy. Learn the signs of a flash over. Also think of this all of you MONDAY quarter backers if you have ever been in a flash over you would know that its not a style of nozzle that you need, its a way out because it happens so fast you will never see it coming, Oh ya Its hot in there. Your body heat will rise so fast you maybe the one on fire. All you will want to do is find a way to get out and get out of your gear. You will also have a hard time breathing while hyper ventilating. FOG does not make it any cooler in there guys putting the fire out does Foging is a practice that should be used ONLY for hydraulic ventilation, trash and car fire not structural fire attack.

Permalink Reply by Mike Puchol on July 19, 2009 at 6:59pm

I see two main issues here. The first is that there is a wide-spread misunderstanding of fog pattern techniques and their use in pre-flashover situations. I say pre-flashover very specifically, as once the flashover is rolling all you want to do is GET OUT, never mind getting your crayons out to start penciling or debating what size bore your nozzle has or if you want to bring in the lobsters to steam-cook them while you're at it.

To make things clear: nobody is saying fog is used to extinguish the fire, but only to break a brewing flashover, giving the team more time to use a straight stream to knock down the fire. What you see in can simulators is the repeated application of fog to teach students the technique - I have talked with a few firefighters who see videos on YouTube and believe they are watching an extinguishing technique - wrong! You need to combine fog with straight stream in the right way, time and place, as was mentioned by George. If you don't know or don't have enough experience to gauge this, then at the first sign of an impending flashover, GET OUT, and fight from a safe distance. There is no shame in admitting one is not qualified or experienced in the use of certain techniques, but there is shame in dissing them because one is not familiar with them.

The second issue deals with the basic physics on how fires are extinguished, and fire gasses cooled. Ed hit it square on - to reduce the temperature of the fire gases, or to extinguish the fire, you need to get water turned into steam. There is no way to break the laws of physics here. If you lower steam production, you are letting water run off without having absorbed heat. As Ed says, the RIGHT amount of fog will produce the RIGHT amount of steam which will allow fire gasses to contract, making conditions more bearable, pushing back flashover and buying you time to attack the fire with a straight stream. Assuming that the technique is to place yourself under a water umbrella is stupid - that will produce the WRONG amount of steam and will get you cooked, or if you make it out, a permanent advocate of solid bores and straight streams.

For those of you who haven't read it, I recommend Paul Grimwood's "Euro Firefighter", it's a great mix of fire service history, hard physics, and fog techniques.

Permalink Reply by Russ Chapman on September 5, 2009 at 9:15am

Mr Hartin brings up great, and very much researched points. The scientific data is in. But it boils down to a simple exercise. Take a hoseline with a combi nozzle out on a windy day, and open the line with the wind to your back on SS. Now open it to full fog, partrail fog, what ever. Isnt it amazing that there is water going backwards against the wind? Fog nozzles create a negative vortex right about where your head is. The only way is like Ray said, a bunch of water, and conduct emergency action drills on how to back out when your are in a very low position. As far as Royer and Nelson? Please leave them out of it. They probably are responsible for burning up more guys than we can imagine due to the bastardation of Layman's tactics.

Permalink Reply by Daryl Liggins on September 21, 2010 at 10:35pm

This scenario sounds like there were tactical problems that led up to the event. The solid or straight stream will afford you the reach to hit rooms of fire prior to entering them. Safety can come from using the reach of the stream. If heat conditions are that severe and not getting better with the line fully open usually we are not at the seat of the fire. In my experience the fire was usually below us in a basement. hold your position and get a line to the seat of the fire. If you are at the seat of the fire and the heat halts your advance you need more water and/or more ventilation. A fog pattern is not the answer.

Permalink Reply by Russ Chapman on September 22, 2010 at 10:49am

Hey guys, the bottom line is this, like Ray said, A TON OF WATER. But, if you wish to use a fog pattern inside a burning structure, start carryinig mustard. Poor it all over you before you go in. Because you will make yourself and anyone in the place a boiled hot dog by the time you get out. Leave the fog patterns for the burning propane gas drills when you use those props. Fog patterns have no business inside a burning structure fire. Read 'Little Drops Of Water, Fifty Years Later" by the late Lt Andy Fredericks. You can Google it or search the archives on FE.

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