Opening the Nozzle in Smoke

Replies to This Discussion

Permalink Reply by John Ceriello on February 4, 2011 at 9:31am

Now this is what a call a discussion. I've spoken to Paul a number of times about this. Is it possible that in a container these concepts work very well, however when applied in the field with all the crazy variables that can exist it does not work as well? When the temp at ceiling level is elevated and the water is introduced the absorption of heat converting to steam will cool the area. I agree that if it is hotter 212 F how the steam not be hotter, if it is momentarily but it is heading down to that temp. contacting the fire gases along the way. Are you sure the staem was melting your helmet not fire gases? If i come up to a fire scene and I have fire blowing out the front of a tax-payer(1 story commercial) would you use the pulsing nozzle technique on this fire? Or is it when it is a smaller type fire and the need it to get down the hallway that has fire gases leaving an apartment moving in your direction?

Pierre-Louis LAMBALLAIS said:

John Ceriello said:

I just not sure if steam follows the laws of an ideal gas, when it is mixed with many other products of combustion in a fire building. Does that make sense?

yes. In fact mix gaz are very hard to study. In fact, maybe its hard to rise over the 212F but in a fire you have a HRR producing far more than this temp. So in a 500°F situation, steam will not stay at 212°F.

Last time I gave a flashover instructor  course, we were on our knees, facing the fire and practising noozle tech. I had a few heat sensation at the top of my head so I touch my helmet (we have MSG Gallet F1). The top part of the helmet was melting, like a chewingum and the helmet of the first row of traines was doing the same. And we were on our knews.. The therrmocouple recorded about 200°C (392°F)  to 240°C (482°F)  at helmet level.

In these conditions, the water cool a lot but the steam continue rising in temp. And we were at 20' from the seat of fire.

In a flashover container, with an opening of 1/3 of a second of a nozzle with flow rate at 30GPM, we destroy a sea of flame of 1,5' thick, 8' wide and 8' long  ( ' is for feet that's right??) . But if we open the nozzle a longer time (eg 1 sec) or use a higher flow rate, we see we have exactly the same effect, but suffer a "piston effect" from steam.

After a good period of thinking, we admit it was logical: we flow water at some distance, and some surface. If you open a nozzle 1 second or 1 min this will change nothing: the surface you will cover will be the same (assuming of course you d'ont move the nozzle).

If we compute the heat of smoke and compute the volume of water needed, according to the rate of absortion; we conclude that the best effect would be to have a nozzle wih wide angle (60°), at 45° from the ground, a flow rate of 30 to 40GPM and an opening of 1/3 of a second. That's funny to see that, on 1999 on his book "Fog Attack", Paul Grimwood, after some test, conclued the same.

With more water, you will not do "better": when smoke is cold, smoke is cold and you can't turn it to ice. The water you've sent too, will have another effect: producing over heated steam as it splash on over heated surface.

Regards

Pierre-Louis

PS: I'll search for steam temp in fire. But I must admit real data are not so numerous. For our course, we have a set of 16 thermocouples, but checking data is not very easy as humidity, wind and so on affect a lot the data.

Permalink Reply by John Ceriello on February 4, 2011 at 9:45am

We have begun the process of understanding this, Pierre is correct in saying" it's all about the air" what I mean is our fires and yours are air regulated. UL recent study will begin to get to the masses in the American fire service, just give it a little time. Many firefighters here think that more ventilation is the answer, that is why we are seeing more flashover situations. We understand that water on the fire is what needs to be accomplished, you guys think the pulsing will get you to the seat of the fire quicker and safely. We still are going to battle it with big water, I'm somewhere in the middle. That was the intent of the beginning of this blog from Ray, we are at different ends of the spectrum, however I think we can learn from you and you can learn from us. everyone keep talking. JC

Russ Chapman said:

Pierre.. you absolutley do not have the same fire load as us.  I know for a fact that you do not use the same amount of POL products.  Your penciling and fogs have burnt up guys.  Let us just agree to disagree with this.  You fight your fires your way, we will fight ours in our way.  We have a ton more than you, and the experience to prove it.  Enough said, please do not respond.

Pierre-Louis LAMBALLAIS said:

- For Adam: you can find also info about the impact of humidty, here:

http://www.ncdc.noaa.gov/temp-and-precip/heat-stress.html

- For John: you will suffer more with a wet turn out gear than with a dry one. See previous doc.

- For Russ

We have a totally different fire load than you.  Fog for interior attack burns too many firemen.  This will not work here.

We have all the same furniture: sofa, harmchair, bed, television. Do you think I'm living in a tipee, in the far deep of the forest, using a bicycle to produce electricty for my internet access :) :) :)

Now I'm living in Brasilia. The town named Aquas Claras has builing of about 30 floors, same shops than in the USA (I've a Wallmart at 300 meters from my appartement) or Europe. The fire load? Check for real data. You will see that the difference disappear about 30 years ago. Also, you must know that, in structural fire, the fire load is not the key element. The max HRR of a fire in a structural environnement depend on oxygen. It was first compute in 1917 by Thornton.

see http://jfs.sagepub.com/content/2/5/380.abstract

also:

nvl.nist.gov/pub/nistpubs/sp958-lide/280-282.pdf

As you see, Thornton is an American guy, and the last doc is... from the NIST.

Or maybe you think you have less fire load than we have? which can be true. The only difference you have, today, is that in many residencial area you have wooden houses. So you can cut, open wide and so on. In Europe, cutting a wall like you do with an Halligan Bar is impossible as we have concret houses. But, as I indicate previously, you will face, soon, very big problem with the new houses.

Do you know these guys:

http://nypassivehouse.org/

It's not a European nightmare. It's YOUR next nightmare. And this nightmare is from... New York.

Stop believing your fire are differents. Change. You don't know what these houses are. I know. And I can only tell you to change. Quickly my friend. Quickly.

 

Best regards

Pierre-Louis

 

Permalink Reply by Pierre-Louis LAMBALLAIS on February 4, 2011 at 9:59am

John Ceriello said:

Now this is what a call a discussion. I've spoken to Paul a number of times about this. Is it possible that in a container these concepts work very well, however when applied in the field with all the crazy variables that can exist it does not work as well?

Well in fact we discover than the container is a harder situation. Notice we dont use two level container and we don't have top vent. In a container, wall and ceiling are made of metal. If you strike the metal, you produce a lot of steam. In an appartment, it's not so important. As we know that, on the fire scene, the stress and population "pressure" tend to disminish the quality of what you do, we instruct the guy to avoid touching the wall and ceiling (and we can easily listen to the noise of water againts metal to correct the student). The goal is to have a perfect gesture, to get a "correct" one on the fire scene.

Concerning the fact it works or not on real fire scene, we know it work fine. I instrustedmany FF in Europe and the change is visible. The amount of water use is divided some by 100, time of extinction is less than 5 minutes and so on.

 

When the temp at ceiling level is elevated and the water is introduced the absorption of heat converting to steam will cool the area. I agree that if it is hotter 212 F how the steam not be hotter, if it is momentarily but it is heading down to that temp. contacting the fire gases along the way. Are you sure the staem was melting your helmet not fire gases?

in this cases, it was the heat, due to the radiative feedback from the smoke layer; Not the steam. It was a special burn, at the end of the two week instructor cours, so with guy knowing perfectlyt how to use a nozzle, so no over production of steam

If i come up to a fire scene and I have fire blowing out the front of a tax-payer(1 story commercial) would you use the pulsing nozzle technique on this fire? Or is it when it is a smaller type fire and the need it to get down the hallway that has fire gases leaving an apartment moving in your direction?

It don't depend really on the size of the fire. It depend on the fact you can see the seat or not. If you can see it, flow water on it. But if you have to enter and search for the fire, you must remember one point: "Ceilling = warning!" The fire release 30% of radiative energy, but 70% as convective one, so to the top. If you have a ceilling over your head, convective heat will stay prisonner and will travel over you. In this case you must cool the upper layer.

The main problem is distance: if you have a 20' ceilling height, you would be unable to cool the upper part of the layer.

This mean the 3D methods are perfect for appartement, small shops, houses and so on. But completly unusefull on outisde fire (againt a car fire) or in industrial conditions.

 

Regards

Pierre-Louis

Permalink Reply by John Ceriello on February 4, 2011 at 10:03pm

I've read the links, I do not see where the info shows how in a structure fire we are creating superheated steam? Yes in a steam engine you will or when the pressure is increased, however when is that happening in a fire? The engineers I spoke with produce steam everyday for Con-Edison, I do believe they are experts, remember we are firefighters. Can I ask you why was the pulsing technique even looked at in the beginning. In most cases technique change comes in response to problems, what were the problems that lead to this change in tactic. Was it firefighter deaths, was it getting chased out of hallways by steam, was it a water damage issue? 

John Ceriello said:

Does superheated steam need to be pressurized to be hotter than 212 F? I believe it does. How does this pressurization occur in a fire building.Is not it cooling the entire time it exists? When I get a chance I will read your links, then respond. I do not believe your fires are different, lets make that clear. I just not sure if steam follows the laws of an ideal gas, when it is mixed with many other products of combustion in a fire building. Does that make sense? By the way lets keep things intelligent when we discus this topic, remember we are professional firefighters trying to learn from each other, at least that is my angle. JC

Pierre-Louis LAMBALLAIS said:

John Ceriello said:

What I've been told is that steam is not hotter than 212 F, it's still there it's just not hotter that 212 F. The Europeans disagree with that. 

Law of physics are not the same in Europe and in the USA?

Be serious John. Here is a document from Massachusetts! It's not really in Europe.

http://www.massengineers.com/documents/properties_of_steam_and_wate...

And if you look for steam engineers on the web, you'll find that:

http://www.spiraxsarco.com/resources/steam-engineering-tutorials/st...

I suppose your "steam engineers" friend was sleeping during the "Superheated steam" course.:)  :)  :)

Best regards

Pierre-Louis

Permalink Reply by Pierre-Louis LAMBALLAIS on February 5, 2011 at 6:24am

John Ceriello said:

I've read the links, I do not see where the info shows how in a structure fire we are creating superheated steam? Yes in a steam engine you will or when the pressure is increased, however when is that happening in a fire? The engineers I spoke with produce steam everyday for Con-Edison, I do believe they are experts, remember we are firefighters.

 

Im' not only that. Im' software engenieer and quality expert. I agree the production of superheated steam is far more easy with over pressure, but in many cases the steam itself is pressure generator.

Just notice that from the Spirax Sarco web site "If the saturated steam produced in a boiler is exposed to a surface with a higher temperature, its temperature will increase above the evaporating temperature.

The steam is then described as superheated by the number of temperature degrees through which it has been heated above saturation temperature."

 

This is what happened in a compartement fire. Notice also the production of steam, due to the expansion of it, will produce over pressure. What would be interesting is to compute the result to see if this overpressure will "help" the production of superheated steam so that, in the case of our use of water, the steam production would  "help" itself. In the case of your friend, the most difficult with "expert" is to describe them exactly what you want to ask. Because in many cases they just listen to the beginning of the question then give you a complet answer which in many case 70% don't really apply to the initial question. As an expert I can admit we are great specialists of answer without real link to the question. :)  :)   :)   :)

 

See also that:

http://en.wikipedia.org/wiki/Boiler

 

I think you friend are talking of Spercriticla steam generator as we are (I think) more closer to this:

http://en.wikipedia.org/wiki/Superheater

 

This part of the discussion is interresting because on the container, we don't feel "wet" and this article talk about "dry" and "wet" steam.

 

Can I ask you why was the pulsing technique even looked at in the beginning. In most cases technique change comes in response to problems, what were the problems that lead to this change in tactic. Was it firefighter deaths, was it getting chased out of hallways by steam, was it a water damage issue? 

Really I don't know. What I know is that the real story seem to start in Sweeden about 30 years ago. The info I have (take care, 'Im not sure of the real truth of all of that) is that in Stockholm, a fire killed two FF and the acccident was described as very fast with a big ball of fire, like a gas event. A few weeks after, the same case happened again. So two Sweedish FF started to see what was happening. Because of the high price of test, they just buy a sea container and put the fire inside. They start to see some strange flames, far away from the seat of fire, and so discoverd that smoke was not only a black cloud, disturbing visibility and health, but that is was a new fuel. In act, they just discove than a room fire is made not only of a solid fuel, but of a solid one, which create an gaseous one.

Notice the company selling container for training in the US, wih name sounding like "Sweede" seems to be far from this spririt. Double level container are not good for such training and the real sweedish container are at very low price. The containers we used cost a max of 2500 Euros (3400 US$), ready to use with transportation included and the time to transform them is about 1 day for two guys knowing how to cut metal and puot bricks on the ground (so very basic!) and the cost I give included the bricks and cement.

 

Discoverting this "gaseous fuel" ask a big question: the way to fight that. The solid fuel must be consider at a 2D problem. When I flow water, I can move my nozzle form left to right (one axis) and up and down (second axis). While considering a solid fire, the third axis (close to me or far away) is not a problem: as the water will strike the solid fuel, the solid will stop water.

On the fire service, it's easy to check the difficulty of this thrid axis: draw a circle on the wall, and ask a FF to use a nozzle, at about 20' from the wall, and put water inside the circle. You will see the FF is immediatly able to do that. Then, draw the same circle on the ground, and ask the FF to stand at the distance he want, but in order to put water inside this circle. You will see that it's hard. The third axis is a real problem.

So the Sweedish introduce  the concept of 3D which is, in fact the concept of cooling this gaseous fuel. In order to deal with the third axis the use pulsing, which is opening and clothing the nozzle, very quickly. The flow of water is minimum and stay close to the FF. He then can advence by one or two meter, cool again, and so on, to reach the seat of the fire, while cooling this dangerous smoke.

What we know discover is that this gaseous fuel is the key element. It's hard to explain here, but during our course we just use an array saying that:

Step 1 - At the begining, the fire is fuel controled beacuse there is more air than needed. The element which control the fire is visible. The fuel (sofa) is visible, solid, static and spread is slow.

Step 2 - After a short time, the fire create heavy smoke. At this moment, thinks are completly different. The fire is air controled and this element which controle the fire is invisble (air). Now, the fuel is, in a large %, a gaseous one. So the smoke is the main fuel. This new fuel is visible, but its gaseous, mobile, and spread is fast

Step 3 - When the roof collapsed, we come back to the first step: fuel controled fire, fuel is solid, visible, static and spred is low

 

What we must consider is that before 1973 we didnt have problem. Before this date, we didnt' have isolation or double glass window. So the fire was going directly to step 1 to step 3: if the window breaks during stage 1, you go direclty to step 3 and can use solide bore from the outside. Why 1973? Because in october 1973, it was the Kippour's war. USA (you) and  European (we) were helping Israel againt Arabic countries. And the organisation of Petrol producer decided to close the flow of petrol, so the price rise a lot. As US is a petrol producer, the effect was of no real impact against you. But it was dramatic for us. I'm 51 years old, and I remember of people trying to glue plastic sheet over windows to "imagine" a kind of double glass for isolation!

The change in fire was not immediate, of course. Before 1973, we were facing such special fire, like you were: cellar fire are confined fire, hard to deal with. But when you have 1% of the fire which are cellar fire, why bother? But after 1973, all appartement and house fire turn step by step to be kind of cellar fire. When you have 5% of "cellar fire", then 10%, then 20%, then 30% and so on, you start to change. Like with air bags in cars: one car with air bag over 10 milions dont' create a need to change. 50% of car with air bag start to ask many question. That's the same.

Today, the fossil fuel is not a European problem but a world wide one. Remember Ale Gore"s film "An Inconvenient Truth". So you start to face isolated house and you start to face the same problem as ours: arriving in front of a house, with smoke and no flame. And the team stay there, without knowing exactly what to do. And when you start breaking windows, you just give the fire what it's waiting for: air. And when you enter to save, you just try to win a race in front of a fire spreading in gas. But the only one I know who run faster than the fire, is James Bond. :)

So as you have a nozzle, you just do what you learn: flow, flow, flow, flow. That what exacly I learned to do, and that we were doing. But remember the Predator first film, when the team was using all their arms for minutes against a kind of gasous enemy. Noise, stress, shouts, but nothing more.

 

On the other hand, we are discovering that this change in way of doing, produce other effects that we didn't really imagine: we disminish water damage, so we disminish destruction of furnitures, so we disminish collaspse of house (water is heavy). We reduce the time of extinction so it cost less for the fire service (running a pumper for hours costs a lot),  we have less inujries (less time on the fire ground with less chance to slip on water).

I think the goal was not well defined. It was surely not to avoid water damage and not to avoid FF death. But we avoid water damage and disminished accident as a result of a better firefighting. Army speak of "Collateral damage". Maybe here we can speak of "Collateral benefits".

Today, we see that "Everyone goes home" is not really winning the war againts LODD. Because the LOOD in New Jersey is far from Texas. It's human. An accident in north of France has no impact on the fire service in the South of France. Accident are always for the other, not for me! The challenge to disminish LODD will not be winned with poster and commercial add. It will be winned by a change in the fire ground. And maybe in a change of extinction way of doing.

 

Notice if you want a container, and want to build it by yourself, I can help you and show you all of that for the price of a plane ticket and some good beers :)

 

Best regards, sorrry for my poor english, and thanks very much for the discussion.

Pierre-Louis

Permalink Reply by John Ceriello on February 5, 2011 at 8:22am

That was a lot of information to digest, however I will and then respond. very good conversation! JC

Pierre-Louis LAMBALLAIS said:

John Ceriello said:

I've read the links, I do not see where the info shows how in a structure fire we are creating superheated steam? Yes in a steam engine you will or when the pressure is increased, however when is that happening in a fire? The engineers I spoke with produce steam everyday for Con-Edison, I do believe they are experts, remember we are firefighters.

 

Im' not only that. Im' software engenieer and quality expert. I agree the production of superheated steam is far more easy with over pressure, but in many cases the steam itself is pressure generator.

Just notice that from the Spirax Sarco web site "If the saturated steam produced in a boiler is exposed to a surface with a higher temperature, its temperature will increase above the evaporating temperature.

The steam is then described as superheated by the number of temperature degrees through which it has been heated above saturation temperature."

 

This is what happened in a compartement fire. Notice also the production of steam, due to the expansion of it, will produce over pressure. What would be interesting is to compute the result to see if this overpressure will "help" the production of superheated steam so that, in the case of our use of water, the steam production would  "help" itself. In the case of your friend, the most difficult with "expert" is to describe them exactly what you want to ask. Because in many cases they just listen to the beginning of the question then give you a complet answer which in many case 70% don't really apply to the initial question. As an expert I can admit we are great specialists of answer without real link to the question. :)  :)   :)   :)

 

See also that:

http://en.wikipedia.org/wiki/Boiler

 

I think you friend are talking of Spercriticla steam generator as we are (I think) more closer to this:

http://en.wikipedia.org/wiki/Superheater

 

This part of the discussion is interresting because on the container, we don't feel "wet" and this article talk about "dry" and "wet" steam.

 

Can I ask you why was the pulsing technique even looked at in the beginning. In most cases technique change comes in response to problems, what were the problems that lead to this change in tactic. Was it firefighter deaths, was it getting chased out of hallways by steam, was it a water damage issue? 

Really I don't know. What I know is that the real story seem to start in Sweeden about 30 years ago. The info I have (take care, 'Im not sure of the real truth of all of that) is that in Stockholm, a fire killed two FF and the acccident was described as very fast with a big ball of fire, like a gas event. A few weeks after, the same case happened again. So two Sweedish FF started to see what was happening. Because of the high price of test, they just buy a sea container and put the fire inside. They start to see some strange flames, far away from the seat of fire, and so discoverd that smoke was not only a black cloud, disturbing visibility and health, but that is was a new fuel. In act, they just discove than a room fire is made not only of a solid fuel, but of a solid one, which create an gaseous one.

Notice the company selling container for training in the US, wih name sounding like "Sweede" seems to be far from this spririt. Double level container are not good for such training and the real sweedish container are at very low price. The containers we used cost a max of 2500 Euros (3400 US$), ready to use with transportation included and the time to transform them is about 1 day for two guys knowing how to cut metal and puot bricks on the ground (so very basic!) and the cost I give included the bricks and cement.

 

Discoverting this "gaseous fuel" ask a big question: the way to fight that. The solid fuel must be consider at a 2D problem. When I flow water, I can move my nozzle form left to right (one axis) and up and down (second axis). While considering a solid fire, the third axis (close to me or far away) is not a problem: as the water will strike the solid fuel, the solid will stop water.

On the fire service, it's easy to check the difficulty of this thrid axis: draw a circle on the wall, and ask a FF to use a nozzle, at about 20' from the wall, and put water inside the circle. You will see the FF is immediatly able to do that. Then, draw the same circle on the ground, and ask the FF to stand at the distance he want, but in order to put water inside this circle. You will see that it's hard. The third axis is a real problem.

So the Sweedish introduce  the concept of 3D which is, in fact the concept of cooling this gaseous fuel. In order to deal with the third axis the use pulsing, which is opening and clothing the nozzle, very quickly. The flow of water is minimum and stay close to the FF. He then can advence by one or two meter, cool again, and so on, to reach the seat of the fire, while cooling this dangerous smoke.

What we know discover is that this gaseous fuel is the key element. It's hard to explain here, but during our course we just use an array saying that:

Step 1 - At the begining, the fire is fuel controled beacuse there is more air than needed. The element which control the fire is visible. The fuel (sofa) is visible, solid, static and spread is slow.

Step 2 - After a short time, the fire create heavy smoke. At this moment, thinks are completly different. The fire is air controled and this element which controle the fire is invisble (air). Now, the fuel is, in a large %, a gaseous one. So the smoke is the main fuel. This new fuel is visible, but its gaseous, mobile, and spread is fast

Step 3 - When the roof collapsed, we come back to the first step: fuel controled fire, fuel is solid, visible, static and spred is low

 

What we must consider is that before 1973 we didnt have problem. Before this date, we didnt' have isolation or double glass window. So the fire was going directly to step 1 to step 3: if the window breaks during stage 1, you go direclty to step 3 and can use solide bore from the outside. Why 1973? Because in october 1973, it was the Kippour's war. USA (you) and  European (we) were helping Israel againt Arabic countries. And the organisation of Petrol producer decided to close the flow of petrol, so the price rise a lot. As US is a petrol producer, the effect was of no real impact against you. But it was dramatic for us. I'm 51 years old, and I remember of people trying to glue plastic sheet over windows to "imagine" a kind of double glass for isolation!

The change in fire was not immediate, of course. Before 1973, we were facing such special fire, like you were: cellar fire are confined fire, hard to deal with. But when you have 1% of the fire which are cellar fire, why bother? But after 1973, all appartement and house fire turn step by step to be kind of cellar fire. When you have 5% of "cellar fire", then 10%, then 20%, then 30% and so on, you start to change. Like with air bags in cars: one car with air bag over 10 milions dont' create a need to change. 50% of car with air bag start to ask many question. That's the same.

Today, the fossil fuel is not a European problem but a world wide one. Remember Ale Gore"s film "An Inconvenient Truth". So you start to face isolated house and you start to face the same problem as ours: arriving in front of a house, with smoke and no flame. And the team stay there, without knowing exactly what to do. And when you start breaking windows, you just give the fire what it's waiting for: air. And when you enter to save, you just try to win a race in front of a fire spreading in gas. But the only one I know who run faster than the fire, is James Bond. :)

So as you have a nozzle, you just do what you learn: flow, flow, flow, flow. That what exacly I learned to do, and that we were doing. But remember the Predator first film, when the team was using all their arms for minutes against a kind of gasous enemy. Noise, stress, shouts, but nothing more.

 

On the other hand, we are discovering that this change in way of doing, produce other effects that we didn't really imagine: we disminish water damage, so we disminish destruction of furnitures, so we disminish collaspse of house (water is heavy). We reduce the time of extinction so it cost less for the fire service (running a pumper for hours costs a lot),  we have less inujries (less time on the fire ground with less chance to slip on water).

I think the goal was not well defined. It was surely not to avoid water damage and not to avoid FF death. But we avoid water damage and disminished accident as a result of a better firefighting. Army speak of "Collateral damage". Maybe here we can speak of "Collateral benefits".

Today, we see that "Everyone goes home" is not really winning the war againts LODD. Because the LOOD in New Jersey is far from Texas. It's human. An accident in north of France has no impact on the fire service in the South of France. Accident are always for the other, not for me! The challenge to disminish LODD will not be winned with poster and commercial add. It will be winned by a change in the fire ground. And maybe in a change of extinction way of doing.

 

Notice if you want a container, and want to build it by yourself, I can help you and show you all of that for the price of a plane ticket and some good beers :)

 

Best regards, sorrry for my poor english, and thanks very much for the discussion.

Pierre-Louis

Permalink Reply by John Ceriello on February 5, 2011 at 8:38am

Wikipedia links are good, however I'm still not seeing how the production of superheated steam in a fire compartment. I'll keep looking.

Pierre-Louis LAMBALLAIS said:

John Ceriello said:

I've read the links, I do not see where the info shows how in a structure fire we are creating superheated steam? Yes in a steam engine you will or when the pressure is increased, however when is that happening in a fire? The engineers I spoke with produce steam everyday for Con-Edison, I do believe they are experts, remember we are firefighters.

 

Im' not only that. Im' software engenieer and quality expert. I agree the production of superheated steam is far more easy with over pressure, but in many cases the steam itself is pressure generator.

Just notice that from the Spirax Sarco web site "If the saturated steam produced in a boiler is exposed to a surface with a higher temperature, its temperature will increase above the evaporating temperature.

The steam is then described as superheated by the number of temperature degrees through which it has been heated above saturation temperature."

 

This is what happened in a compartement fire. Notice also the production of steam, due to the expansion of it, will produce over pressure. What would be interesting is to compute the result to see if this overpressure will "help" the production of superheated steam so that, in the case of our use of water, the steam production would  "help" itself. In the case of your friend, the most difficult with "expert" is to describe them exactly what you want to ask. Because in many cases they just listen to the beginning of the question then give you a complet answer which in many case 70% don't really apply to the initial question. As an expert I can admit we are great specialists of answer without real link to the question. :)  :)   :)   :)

 

See also that:

http://en.wikipedia.org/wiki/Boiler

 

I think you friend are talking of Spercriticla steam generator as we are (I think) more closer to this:

http://en.wikipedia.org/wiki/Superheater

 

This part of the discussion is interresting because on the container, we don't feel "wet" and this article talk about "dry" and "wet" steam.

 

Can I ask you why was the pulsing technique even looked at in the beginning. In most cases technique change comes in response to problems, what were the problems that lead to this change in tactic. Was it firefighter deaths, was it getting chased out of hallways by steam, was it a water damage issue? 

Really I don't know. What I know is that the real story seem to start in Sweeden about 30 years ago. The info I have (take care, 'Im not sure of the real truth of all of that) is that in Stockholm, a fire killed two FF and the acccident was described as very fast with a big ball of fire, like a gas event. A few weeks after, the same case happened again. So two Sweedish FF started to see what was happening. Because of the high price of test, they just buy a sea container and put the fire inside. They start to see some strange flames, far away from the seat of fire, and so discoverd that smoke was not only a black cloud, disturbing visibility and health, but that is was a new fuel. In act, they just discove than a room fire is made not only of a solid fuel, but of a solid one, which create an gaseous one.

Notice the company selling container for training in the US, wih name sounding like "Sweede" seems to be far from this spririt. Double level container are not good for such training and the real sweedish container are at very low price. The containers we used cost a max of 2500 Euros (3400 US$), ready to use with transportation included and the time to transform them is about 1 day for two guys knowing how to cut metal and puot bricks on the ground (so very basic!) and the cost I give included the bricks and cement.

 

Discoverting this "gaseous fuel" ask a big question: the way to fight that. The solid fuel must be consider at a 2D problem. When I flow water, I can move my nozzle form left to right (one axis) and up and down (second axis). While considering a solid fire, the third axis (close to me or far away) is not a problem: as the water will strike the solid fuel, the solid will stop water.

On the fire service, it's easy to check the difficulty of this thrid axis: draw a circle on the wall, and ask a FF to use a nozzle, at about 20' from the wall, and put water inside the circle. You will see the FF is immediatly able to do that. Then, draw the same circle on the ground, and ask the FF to stand at the distance he want, but in order to put water inside this circle. You will see that it's hard. The third axis is a real problem.

So the Sweedish introduce  the concept of 3D which is, in fact the concept of cooling this gaseous fuel. In order to deal with the third axis the use pulsing, which is opening and clothing the nozzle, very quickly. The flow of water is minimum and stay close to the FF. He then can advence by one or two meter, cool again, and so on, to reach the seat of the fire, while cooling this dangerous smoke.

What we know discover is that this gaseous fuel is the key element. It's hard to explain here, but during our course we just use an array saying that:

Step 1 - At the begining, the fire is fuel controled beacuse there is more air than needed. The element which control the fire is visible. The fuel (sofa) is visible, solid, static and spread is slow.

Step 2 - After a short time, the fire create heavy smoke. At this moment, thinks are completly different. The fire is air controled and this element which controle the fire is invisble (air). Now, the fuel is, in a large %, a gaseous one. So the smoke is the main fuel. This new fuel is visible, but its gaseous, mobile, and spread is fast

Step 3 - When the roof collapsed, we come back to the first step: fuel controled fire, fuel is solid, visible, static and spred is low

 

What we must consider is that before 1973 we didnt have problem. Before this date, we didnt' have isolation or double glass window. So the fire was going directly to step 1 to step 3: if the window breaks during stage 1, you go direclty to step 3 and can use solide bore from the outside. Why 1973? Because in october 1973, it was the Kippour's war. USA (you) and  European (we) were helping Israel againt Arabic countries. And the organisation of Petrol producer decided to close the flow of petrol, so the price rise a lot. As US is a petrol producer, the effect was of no real impact against you. But it was dramatic for us. I'm 51 years old, and I remember of people trying to glue plastic sheet over windows to "imagine" a kind of double glass for isolation!

The change in fire was not immediate, of course. Before 1973, we were facing such special fire, like you were: cellar fire are confined fire, hard to deal with. But when you have 1% of the fire which are cellar fire, why bother? But after 1973, all appartement and house fire turn step by step to be kind of cellar fire. When you have 5% of "cellar fire", then 10%, then 20%, then 30% and so on, you start to change. Like with air bags in cars: one car with air bag over 10 milions dont' create a need to change. 50% of car with air bag start to ask many question. That's the same.

Today, the fossil fuel is not a European problem but a world wide one. Remember Ale Gore"s film "An Inconvenient Truth". So you start to face isolated house and you start to face the same problem as ours: arriving in front of a house, with smoke and no flame. And the team stay there, without knowing exactly what to do. And when you start breaking windows, you just give the fire what it's waiting for: air. And when you enter to save, you just try to win a race in front of a fire spreading in gas. But the only one I know who run faster than the fire, is James Bond. :)

So as you have a nozzle, you just do what you learn: flow, flow, flow, flow. That what exacly I learned to do, and that we were doing. But remember the Predator first film, when the team was using all their arms for minutes against a kind of gasous enemy. Noise, stress, shouts, but nothing more.

 

On the other hand, we are discovering that this change in way of doing, produce other effects that we didn't really imagine: we disminish water damage, so we disminish destruction of furnitures, so we disminish collaspse of house (water is heavy). We reduce the time of extinction so it cost less for the fire service (running a pumper for hours costs a lot),  we have less inujries (less time on the fire ground with less chance to slip on water).

I think the goal was not well defined. It was surely not to avoid water damage and not to avoid FF death. But we avoid water damage and disminished accident as a result of a better firefighting. Army speak of "Collateral damage". Maybe here we can speak of "Collateral benefits".

Today, we see that "Everyone goes home" is not really winning the war againts LODD. Because the LOOD in New Jersey is far from Texas. It's human. An accident in north of France has no impact on the fire service in the South of France. Accident are always for the other, not for me! The challenge to disminish LODD will not be winned with poster and commercial add. It will be winned by a change in the fire ground. And maybe in a change of extinction way of doing.

 

Notice if you want a container, and want to build it by yourself, I can help you and show you all of that for the price of a plane ticket and some good beers :)

 

Best regards, sorrry for my poor english, and thanks very much for the discussion.

Pierre-Louis

Permalink Reply by Ben Fleagle on February 12, 2011 at 5:23pm

John,

After re-reading this whole thread here, I am in agreement with where you are heading in your comments.  Everyone here has well balanced arguements and our foreign brother is definitely well versed in his stance.  My specialty isn't fire behavior necessarily, I teach building construction, but I fight fires in the same buildings that you guys do and I can relate what you are saying to what I have experienced in my career.  

How many firefighters that die in structure fires today have reached the seat of the fire or even know where it is?  I would venture to say very few.  I agree with Jim in that the water applied directly to the burning surface is the quickest and most effective way to stop the heat, but in reality, I think the issue is not defined by this conversation at all.  Steam burns, radiant heat burns, both hurt.  I believe that American firefighters are dying in fires due to other issues, not nozzle tactics.

My department equips me with a TFT Automatic Pressure Control Nozzle flowing 95 - 300 GPM at 100 psi.  Frequently, I'd really rather have a smoothbore with a few tip choices.  But not because I think the fog nozzle is inadequate, but because I am convinced of the smoothbore's reach and more effective handling.  But the combo tip is what I'm crrently equipped with and we put fires out successfully.  Yes, steam hurts, proper nozzle use can prevent that most of the time and I don't shoot smoke without due cause.  But I mentioned a few months back on this feed that I would rather take my chances with steam than with flashover.  Firefighters are dying due to leadership and command/control issues, lack of training in some instances, lack of manpower and poor communication.  I can't recall any recent Line of Duty deaths due to nozzle choices.  (I keep up on the Line of Duty Death's published but I could have missed something).

 

However, in recent commercial jobs, it has become obvious due to discussions like these and other works by progressive departments, that our efforts to stick with these combo nozzles and smaller lines on such fires has proven unproductive.  I have seen immediately positive results using the smoothbore approach on big lines that are packing a punch.  Why bring a pistol to a pistol fight, bring a big gun.  We are finally going to make some effective changes in that area.  Sorry I don't have a bunch of physics to quote, this discussion is a great read and I mean no harm, but I think we are talking circles around a much different problem.  I shoot smoke when I think it will buy my company more time to hit the seat.  These fires today are very quick to grow out of control and smoke is fuel. 

John Ceriello said:

So what you are saying is you would rather deal with uncontrolled fire gases than steam, my thoughts on that is that they need to be re-examined. I know of a number of firefighters who have died because we did not get water on the fire, yet I know of none that have been killed by steam, civilians included. If any one knows of any then have I would like to hear about it. Yet the fear of steam production is on the foremost on firefighters minds, their focus needs to look at uncontrolled fire gases that is a larger danger. By the way I've spoken to steam engineers and they tell me that steam can not be hotter than 212 F, steam at 212 F will burn you much more than water at 212 F however our gear can handle that for a period of time. 

Adam Miceli said:

"use fog not solid stream. Why? In order to cool something, water has to increase in temp then evaporate. That's physics. In order to do that, water must have a large contact with heat. The more the contact is, the better is the transformation of water so the better is the cooling effect. The problem is that this transformation of state (from liquid to gas) create steam which will burn you."

 

I guess I'm not convinced of the bold statement above. Doesn't the cooling take place when the heated material transfers heat to the cooler water? In the process the water temp rises to 212 F and evaporates. In fact, if you are correct, wouldn't we just use steam spray to extinguish fires. The point being is that the evaporation is a side affect and not a benefit of the cooling process. The reason more contact is better is that it allows more heat transfer. The contact of already heated or smaller particles only succeeds in reducing the cooling power of the water. This is somewhat different in 3D tactics where you need the smaller particles to stay aloft to absorb heat, vs. the larger heavier droplets that fall to rapidly to absorb and the superheated gases. 

 

So, while I'm not a 3D convert or user, I can understand the value from purely theoretical standpoint and why it works for so many, but alas, I cannot see using fog on the actual burning material. Theres's a great article on nozzle/hose selection in this months FE magazine that gets into so specific data supporting the use of solid streams in direct fire attack.

 

As for those who asked about steamed vs. fire/smoke fatalities? I doubt we'd know without a specific study or autopsy. One need only be in a steamed container to understand how the situation can only be far worse for any unprotected victims. Our PPE allows us to withstand far hotter dry heat than wet, our skin also can withstand dry better than wet heat. 

Permalink Reply by Pierre-Louis LAMBALLAIS on February 12, 2011 at 6:10pm

Ben Fleagle said:

John,

***

 

After re-reading this whole thread here, I am in agreement with where you are heading in your comments.  Everyone here has well balanced arguements and our foreign brother is definitely well versed in his stance.  My specialty isn't fire behavior necessarily, I teach building construction, but I fight fires in the same buildings that you guys do and I can relate what you are saying to what I have experienced in my career.  

How many firefighters that die in structure fires today have reached the seat of the fire or even know where it is?  I would venture to say very few.  I agree with Jim in that the water applied directly to the burning surface is the quickest and most effective way to stop the heat, but in reality, I think the issue is not defined by this conversation at all.  Steam burns, radiant heat burns, both hurt.  I believe that American firefighters are dying in fires due to other issues, not nozzle tactics.

My department equips me with a TFT Automatic Pressure Control Nozzle flowing 95 - 300 GPM at 100 psi.  Frequently, I'd really rather have a smoothbore with a few tip choices.  But not because I think the fog nozzle is inadequate, but because I am convinced of the smoothbore's reach and more effective handling.  But the combo tip is what I'm crrently equipped with and we put fires out successfully.  Yes, steam hurts, proper nozzle use can prevent that most of the time and I don't shoot smoke without due cause.  But I mentioned a few months back on this feed that I would rather take my chances with steam than with flashover.  Firefighters are dying due to leadership and command/control issues, lack of training in some instances, lack of manpower and poor communication.  I can't recall any recent Line of Duty deaths due to nozzle choices.  (I keep up on the Line of Duty Death's published but I could have missed something).

 

Hi,

 

I must admit your way of thinking seems a bit strange, or maybve there is something I don't understand (in this case, sorry). You start by saying that only a few FF dying in structure fire have reach the seat of fire. That's perfectly true and if you read doc about LODD you will see this is the case, each time.

Juste a few lines before you say you teach building construction and after that you say you prefer smoothbore's reach. I agree a smoothbore can flow water far away than a foig nozzle. But look at this web site:

http://www.houseplans.com

You will find thousand of house plans. Just take the plan, and imagine a fire in the bedroom. You are at the entrance of the house. What will you do? Even is the smoothborze will be able to flow water at 10 miles, you would not be able to attack the fire, because from the main entrancce of a house, we don't see inside the bedroom.

In fact, to see the seat of fire, you have to go inside. And during all the way from the entrance to the bedroom, the smoothbore will be of a poor help: it will produce steam that will burn you and will not cool correctly the smoke.

 

So my question is still there: what will yo do to go from the main door of an appartement or a house, to the seat of fire? Run? Crawl? Cool the gases?

 

In fact, why are you using smothbore in structural fire as the only way a smothbore is usefull, is the reach, and this has no real benefit inside a house?

 

Why bring a pistol to a pistol fight, bring a big gun. 

When you flow 135GPM with a smothbore, only 20% of the water is used for cooling, due to the poor contact surface between heat and water. With a fog nozzle the surface contact is far more important and you can have up to 80 to 90% of water used for cooling.

So with a smothbore, flowing 135GPM, you flow "usefull water" at 135/100x20 =27 GPM

With a fog nozzle at same flow rate (135GPM), you flow "usefull water" at 135/100x80 = 108 GPM

Its a mistake to talk of the water from tank. We must talk of the water which is really used to cool.

 

In  a few days I'll publish an article about the way Belgium FF fought a fiercy fire in december: flames of 4 to 5 meters from the window, only one pumper and a team of four (all volunters). Time between arriving on scene and complete extinction: 3 min and 20 sec. Proud to say they were my flashover students.

 

Best regards

Pierre-Louis

Permalink Reply by Ben Fleagle on February 12, 2011 at 7:12pm

I understand your confusion.  You're only getting the part I'm writing down here.  I'm sure the brothers over here in the US  are understanding my point because we are taught in the same environment.  I'm not worried about smoothbore vs. fog in a single family or even mutiple family dwelling on the vast majority of room and contents fires.  Give me either one, I'll put the fire out.  The point is that I would open a nozzle on smoke if it meant holding back imminent flashover BECAUSE your math probably works, but I would also not hesitate to use a smoothbore to achieve the same thing, moving rapidly across the ceiling in a short burst, a few feet in front of the nozzle.  IT WOULD BE BEST if we could find our way to the seat of the fire and knock it down with adequate ventilation assisting, but sometimes these things don't all come together as intended.  We're talking about steam burns vs. flashover or high heat exposure due to smoke that is getting ready to flash. Above the dense smoke layer is the ignition of gases at the highest point in the room, pushing that back can buy time.  Either nozzle will work.  Proper PPE use and stretching your neck so that your helmet covers that exposed area can also help keep some of the heat back, but either way, if its so hot that you are needing to do this, than you are already in pain.

The smoothbore with a 2.5" line reaches through layers of heat to the source of the heat when you can't get at the fire due to any number of reasons and delivers more than the required GPM on many of our fires.  The cases I referred to are large buildings with wide-open floor plans (60' - 100').  No offense intended, but keep your math, I'm talking about what I have seen working and what obviously wasn't working.  High fire loads in buildings with exposed steel structural support need to be cooled quickly.  At 150 gpm, with two fog nozzles in use w/straightstream on 1 3/4" lines, there wasn't anywhere near the penetration and rapid cooling that was achieved with a 2.5" line, with a 1 1/8" tip is flowing 265 gpm.  That's only one example.

Its not that I don't respect your math, but this is what I've seen work in fires set deep into large, open areas.  But that is merely a side point, it has nothing to do with opening your nozzle on smoke, which is the real point of this conversation.

 

 

Permalink Reply by John Ceriello on February 12, 2011 at 7:26pm

If you look at LODD deaths where ff's were caught in extreme fire behavior(I'm not looking at running out of air or collapse)

water did not get on the fire so there was probably not much steam around. the point is it is uncontrolled hot fire gases that kill. The steam I've been in during an attack on a fire has been uncomfortable but not unbearable. We do use solid bore nozzles. I agree its not nozzle selection or nozzle tactics that are killing firefighters, it's bad tactics in general, not understanding what we are up against, as well as antiqued knowledge base. Yes, we would go at that commercial fire with 2 and half inch lines with 1"and 1/8th tip. I'd like to see"and 1/4 myself. We would also get Tower Ladders in position for fire attack, when needed.

Why is it so hard for ff's to say they would open up on smoke? almost everyones response was "I would not open on smoke, BUT if it was really hot I would- then the answer is YES I would if I need to! That is what I was trying to get people to say. YES if need be. 

The whole issue of dry vs. wet is; at the same temperature it would be correct to say we can handle dry better than wet, however rarely are at the same temp. 212 F steam will burn you much worse than 212 F water, the steam has 10 times the energy stored. what stored energy does uncontrolled fire gases have? 100s if not 1000s times the stored energy, thats is why they kill! The term superheated makes it sound that the fires of today are supernatural, they are not. peak temperatures of todays fires are a few 100 degrees hotter than 30 years ago. The peak is not the issue it is the heat release rate that gets the temperature into the lethal range much quicker, that is what ff's need to focus on.

We just had 4 situations in and around my fire dept. that had ff's having to bailout of structures, 1 jumped from a 2nd floor window. That is not good. 

Ben Fleagle said:

John,

After re-reading this whole thread here, I am in agreement with where you are heading in your comments.  Everyone here has well balanced arguements and our foreign brother is definitely well versed in his stance.  My specialty isn't fire behavior necessarily, I teach building construction, but I fight fires in the same buildings that you guys do and I can relate what you are saying to what I have experienced in my career.  

How many firefighters that die in structure fires today have reached the seat of the fire or even know where it is?  I would venture to say very few.  I agree with Jim in that the water applied directly to the burning surface is the quickest and most effective way to stop the heat, but in reality, I think the issue is not defined by this conversation at all.  Steam burns, radiant heat burns, both hurt.  I believe that American firefighters are dying in fires due to other issues, not nozzle tactics.

My department equips me with a TFT Automatic Pressure Control Nozzle flowing 95 - 300 GPM at 100 psi.  Frequently, I'd really rather have a smoothbore with a few tip choices.  But not because I think the fog nozzle is inadequate, but because I am convinced of the smoothbore's reach and more effective handling.  But the combo tip is what I'm crrently equipped with and we put fires out successfully.  Yes, steam hurts, proper nozzle use can prevent that most of the time and I don't shoot smoke without due cause.  But I mentioned a few months back on this feed that I would rather take my chances with steam than with flashover.  Firefighters are dying due to leadership and command/control issues, lack of training in some instances, lack of manpower and poor communication.  I can't recall any recent Line of Duty deaths due to nozzle choices.  (I keep up on the Line of Duty Death's published but I could have missed something).

 

However, in recent commercial jobs, it has become obvious due to discussions like these and other works by progressive departments, that our efforts to stick with these combo nozzles and smaller lines on such fires has proven unproductive.  I have seen immediately positive results using the smoothbore approach on big lines that are packing a punch.  Why bring a pistol to a pistol fight, bring a big gun.  We are finally going to make some effective changes in that area.  Sorry I don't have a bunch of physics to quote, this discussion is a great read and I mean no harm, but I think we are talking circles around a much different problem.  I shoot smoke when I think it will buy my company more time to hit the seat.  These fires today are very quick to grow out of control and smoke is fuel. 

John Ceriello said:

So what you are saying is you would rather deal with uncontrolled fire gases than steam, my thoughts on that is that they need to be re-examined. I know of a number of firefighters who have died because we did not get water on the fire, yet I know of none that have been killed by steam, civilians included. If any one knows of any then have I would like to hear about it. Yet the fear of steam production is on the foremost on firefighters minds, their focus needs to look at uncontrolled fire gases that is a larger danger. By the way I've spoken to steam engineers and they tell me that steam can not be hotter than 212 F, steam at 212 F will burn you much more than water at 212 F however our gear can handle that for a period of time. 

Adam Miceli said:

"use fog not solid stream. Why? In order to cool something, water has to increase in temp then evaporate. That's physics. In order to do that, water must have a large contact with heat. The more the contact is, the better is the transformation of water so the better is the cooling effect. The problem is that this transformation of state (from liquid to gas) create steam which will burn you."

 

I guess I'm not convinced of the bold statement above. Doesn't the cooling take place when the heated material transfers heat to the cooler water? In the process the water temp rises to 212 F and evaporates. In fact, if you are correct, wouldn't we just use steam spray to extinguish fires. The point being is that the evaporation is a side affect and not a benefit of the cooling process. The reason more contact is better is that it allows more heat transfer. The contact of already heated or smaller particles only succeeds in reducing the cooling power of the water. This is somewhat different in 3D tactics where you need the smaller particles to stay aloft to absorb heat, vs. the larger heavier droplets that fall to rapidly to absorb and the superheated gases. 

 

So, while I'm not a 3D convert or user, I can understand the value from purely theoretical standpoint and why it works for so many, but alas, I cannot see using fog on the actual burning material. Theres's a great article on nozzle/hose selection in this months FE magazine that gets into so specific data supporting the use of solid streams in direct fire attack.

 

As for those who asked about steamed vs. fire/smoke fatalities? I doubt we'd know without a specific study or autopsy. One need only be in a steamed container to understand how the situation can only be far worse for any unprotected victims. Our PPE allows us to withstand far hotter dry heat than wet, our skin also can withstand dry better than wet heat. 

Permalink Reply by Ben Fleagle on February 12, 2011 at 7:31pm

Amen to that brother.  We are not sizing up the structure or the fire itself.  Dodson's effort to get us to pay attention to "reading the smoke" is very valuable for the simple reason that regardless of whether you agree with his conclusions, he has put the focus on what the smoke is telling us.  We also have had serious close calls due to rapid fire growth and to be honest, failure to ventilate adequately.  Once again John, great topic!

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