gfdtrk4 writes (recent topic)
'Oh Man, My vote goes to the solid bore.
I personally have conducted my own test, not very scientific, however very real world.
Everyone has seen the show on Discovery or T.L.C. or has been in a swede flash(roll)over can!
NEVER SAY NEVER, BUT... contrary to popular belief, you do not have to always be concerned with the fire over your head.
The fire at the the ceiling is just a symptom of the real problem.
Next time you have the opportunity to be in a flashover chamber, ask the instructor to spray the nozzle right into the trash can when it really starts to roll, see what happens. If you are really in need of a steam burn ask the inst. to spray a wide fog at the ceiling ( for PROTECTION :eek
If you still need to spray your fog at the ceiling, use a thermal imager to see the difference between fog & straight.
I love to discuss this topic'.
What concerns me is that these comments come from a training officer who clearly has not grasped some of the basics!
Firstly, these 'flash(roll)over simulators were introduced in Sweden and developed in the UK through the 1980s to teach firefighters the basic concepts of how fire gas layers may form and transport - fire behavior to a limited extent. This was the closest tool that had been developed to date that could would allow firefighters to train safely and effectively at close quarters as a fire progressed to the stages of a simulated flashover....the absence of any fire loading at lower levels prevents any true progression to flashover but enables repeated 'rollovers' which preced the phenomena of flashover by brief seconds - this was as close as a firefighter needs to get to appreciate what is occuring!
The simulators are also used to teach methods of controlling these 'rollovers' to demonstrate to the firefighters that by recognition of events and by intercepting the 'rollovers' at an early stage - the progression to flashover may be avoided.
Whilst these training facilities may be adapted somewhat to accomodate 'local' procedures they were never designed for the use of 'straight' or smooth-bore streams. It was proven scientifically at a very early stage that the most effective and SAFEST way to COOL and INERT super-heated fire gases in the overhead is by 'pulsing' - www.firetactics.com - spurts of water-fog at the ceiling area. This FACT has been proven over and over again by scientific and practical research projects in several countries including USA. The use of thermal imagers ALSO clearly display the true effects of 'pulsed' fog patterns (in comparison to straight/smooth streams) in cooling the overhead - the 'inertion' effect is not visibly apparent though.
These simulation units are, like any form of live fire training - DANGEROUS - if used without due care! In europe we have developed strict safety standards for the design, construction and USE of such training facilities based on nearly 20 years of use. The use of STRAIGHT/SMOOTH-BORE streams in these units is forbidden! Narrowed fog patterns are the closest you will come to such a use and then - water is applied sparingly. The geometrical design of these units does NOT welcome the concepts of 'direct' attack whilst occupied.
To hear a training officer suggest that you do not always need to be concerned with the fire over your head makes me cringe! We should be INDOCTRINATING exactly that hazard into firefighters minds! In a simulator you can SEE the fire in the overhead - in a 'real' fire you may not be able to! Never ever tell a firefighter that he need not concern him/herself with fire in the overhead........thats where the danger lies!
Safe and effective tactics lie in the correct use of the right stream at any particular time - straight streams/smooth-bores/fog patterns ALL have distinct advantages if used correctly and under specific circumstances with a set objective. But 'flash(rollover)' cans/simulators are onl truly safe and effective for a portion of this overall approach - certainly not for teaching straight-stream attack....if thats the way you see it you have missed the point sir!
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Thread: SWEDE Flash (Roll) Over 'Cans'!!
10-05-2001, 01:25 AM #1
SWEDE Flash (Roll) Over 'Cans'!!
10-05-2001, 02:40 AM #2
- Join Date
- May 1999
- City of Brevard Fire Department, NC
I must agree that we should always teach our students to observe the conditions which are present in the overhead but to totally ban an accepted practice of using a stright or solid stream in a container is absurd. The whole intent of a training evoluion is to expose students to different methods of attacking and controlling a fire. The use of a smooth bore line to protect and extinguish fires is a proven method and if an instructor wants to expose or reinforce this tactic than more power to him.
The smooth bore nozzle effectively extinguishes any fire which a nozzle on a narrow pattern pulsing will and this is not a dangerous tactic for use on interior fires as you continually purport in these forums. The only problem with it is that you have a problem with it. The solid stream when applied properly causes overhead fires to extinguish.
I have been witness to a swede style nozzle used in the can and have noticed that the stream creates steam, reduces visibility and causes the thermal layering to change. When pulsing the nozzle the best position to prevent this from occuring is by leaving the nozzle in the straight stream position. But the best way to extinguish the fire, in my opinion of course, is with a solid stream nozzle.
I believe that your fog stream is not the only narrow tool you possess.
10-05-2001, 06:43 PM #3
Hey BFD Lt.....good to talk again
....but to totally ban an accepted practice of using a straight or solid stream in a container is absurd....Hey Lou - I am not in a position to ban but just inform you that can be dangerous! Those containers were never designed for straight stream attack - if you are using yours the way they were originally designed they will have chip-board linings for each burn - the small fire underneath these serves no purpose other than to create heat to these linings that, in turn, produce a flammable gas layer. The containers were designed solely to teach a) fire behavior (observation) and b) to learn how to deal with a forming gas layer - again, 'pulsed' water-fog is proven to be the MOST effective way to handle this....I am not quoting opinion but the results of dozens of scientifically supported tests carried out in a practical format in europe and the USA.
So Lt.....when did I EVER say smooth-bores were a dangerous tactic for use in interior structure fires??? I think you have misread my posts........never ever said that!! I APPROVE OF THIS FORM OF ATTACK in the right situation!
You go on........I have been witness to a swede style nozzle used in the can and have noticed that the stream creates steam, reduces visibility and causes the thermal layering to change. When pulsing the nozzle the best position to prevent this from occuring is by leaving the nozzle in the straight stream position. But the best way to extinguish the fire, in my opinion of course, is with a solid stream nozzle....Again, I would say the instructor is teaching incorrectly! The purpose of pulsing fog patterns is to reduce steam, raise the level of the smoke interface (improving visibility) and also maintaining the thermal balance....any reversal of these effects strongly suggests the instructor is teaching incorrectly or the student isn't quite getting it right! If you are pulsing straight/smoothies then for sure - all the things you suggest will occur. I can only reiterate Lt......if you wanna practise smooth-bore techniques/applications you need a different (larger) type of structure.
Stay safe bro...........
I believe that your fog stream is not the only narrow tool you possess.
10-05-2001, 07:15 PM #4
- Join Date
- Sep 2001
- The southern shore of beautiful Lake Michigan
I am not a very fast typist, and I do not have all the time in the world to sit in front of my computer to "hunt and peck" a 10 page report on my findings based on numerous live fire trainings in acquired structures, 10 short years of personal exp., riding with some of the busiest fire companies in the midwest,& numerous discussions with VERY respected people in our field concerning this topic.
I did not mean to come across as harsh or rude, (sorry) however, I felt as though you were attacking my views without understanding where I am coming from!
I believe something like "... a training officer without proper knowledge of fire behavior..." or something like that.
THOU HAS CAST THE FIRST STONE... AND.. I was just responding to a question on the forum, asking for "OPINIONS" on fog vs. smooth.
As I have stated, I don't have time to devote to this subject (in this medium) that it deserves.
Again, I am sorry if I have upset anyone with my views.FTM-PTB
10-06-2001, 08:40 AM #5
Certainly no offence taken here gdftrk4 and I do respect ANY views on this forum - especially those of firefighters based in busy 'working' areas such as Gary, IND. My point was to draw attention to what I believe is mis-use of 'flashover' (can) simulators and to place greater emphasis on the notion that firefighters need to grasp a greater understanding of fire behavior - it is exactly in the 'overhead' that we need to direct our attention. A failure to appreciate what might lay above our heads has often been cited as a cause for some LODDs in the past.
My views are sometimes taken in opposition to the use of smooth-bore and this is totally incorrect. I feel that 1) straight stream (direct) attack; 2) indirect fog attack; and 3) 3D 'pulsing' offensive fog attack are ALL important tools - as important as each other - in specific situations. I have used ALL 3 forms of water application successfully to deal with fires in different stages of development in varying geometrical layouts....in my mind this is NOT a logical argument....to say its either straight stream or fog! They ALL have distinct advantages.
However, on this topic I am questioning the use of 'Swede Cans' and would welcome an open debate from you and your colleagues and any other firefighters who may have views to express.......are they being used correctly and safely for the purpose they were designed for?
My apologies brother - did not mean to be so arrogant to suggest a fellow firefighting instructor was possibly failing in his job....we all have opinions and constructive debate is a way of learning from each other. I respect your views and would like to continue this 'conference' at some stage.
10-12-2001, 08:14 PM #6
- Join Date
- Apr 2001
- Elkhart, IN, USA
In my opinion the Swede can is a simulator. In this simulator you do not want to put the fire out, just knock it back to allow you to learn from the fire behavior over and over. The simulator is not an extinguishment trainer, but a fire behavior training aid.
10-13-2001, 04:17 AM #7
I would agree with that statement from jmichael - observing fire behaviour is the main purpose of simulator 'can' containers. However, they were also designed to teach and practise 3D gas-cooling using 'pulsing' patterns of water-fog directed into the forming gases. Are you using/teaching/learning this technique as a firefighting tool? Pulsing fog patterns cools the gases more effectively than any other method, shrinks the gases, reduces steam production to acceptable levels, narrows the flammable range of forming fire gases and raise the smoke interface to improve visibility. This method is NOT a substitute for straight/smooth bore attack but an additional tool to enable firefighters to work in safer and controlled conditions.
10-14-2001, 10:09 AM #8
- Join Date
- Apr 2001
- Elkhart, IN, USA
I really think we are using two sets of constants in this debate. If I am not mistaken the nozzle used in the swede container delivers about 30 gpm in fog position, thus knock the rollover back, let the fire behavior training aid roll over again. Small delivery of water, small production of steam.
In fire fighting we deliver large quantities of water, when delivered in fog patterns the production qreat quantities of steam. When these large quantities of water are delivered by a smooth bore/straight stream less steam is generated. Thus the debate over sb/fog. Mr Grimwood is correct when saying fog pattern will cool the environment quicker. In firefighting we need the environment cooled effectiveeffectiveproduction of steam is not effective. Sweeping the ceiling with a smooth bore at 150 to 200 gpm will effectively cool the area. Very little steam will be produced. the stream will have the punch to reach the base of the flames. Effectively putting out the fire.
Steam is produced when water hits the "latent heat of vaporization" the high surface area of the water in a fog pattern allows the water to reach the latent heat of vaporization quicker but the stream will be lacking the punch reach the base of the flame. The steam produced will displace the oxygen in the room the fire will darken down but the high humidity will damage firefighters and civilians. How many times have you had people from Arizona say "but its a dry heat". There is a lot of truth to that.
In closing the absolute best nozzle you can use is the one you have in your hand at the time you need it. Each nozzle has its place in the fire service. Do not use a fire behavior training aid and twist it around to use it for an extinguishment trainer. More water means the fire will go out quicker. If it is burned it is junk if it is wet it will dry.
10-14-2001, 01:00 PM #9
Whilst I agree with a lot you say sir I would wish to comment on a couple of points WITHOUT turning this thread into a smooth-bore .v. fog battleground
The nozzle used in swede style containers should ideally be THE ONE YOU USE FOR REAL FIRES! I am aware that a particular type of (Swedish) nozzle may accompany this form of training because of its low-flow capabilities but that does not help firefighters grasp the techniques associated with 3D nozzle pulsing of fog patterns and enable a transition to 'real-world' fires.
A container burn is a simulation - it is not a real fire. It is used to demonstrate how fire gases form and ignite and is representative of a small fire. You talk of 30 gpm flows - that is a good flow for this size of fire when 'pulsing' the gases and yes - higher flows within these dimensions will over-do the steam!!
In reality, (as an example), a selectable-flow nozzle with flow-ranges of 30 - 150 gpm might be an ideal tool for a one or two roomed fire. Its important to gain an effective droplet range and spinning teeth may ahieve this better than fixed although the cone won't be fully filled.
30 gpm on the lowest setting is great for gas-cooling in small areas - increase this to something like 60 gpm in a larger room. For final extinguishment resort to straight-stream attack, using higher flows if necessary.
Correctly applied water-fog from a well designed nozzle (TFTs - Akrons - Elkharts?) will NOT steam you out....only the user will do that
Dry steam? Thats a term used to describe the type of steam produced by effective 'pulsing' applications. Wet steam burns....but dry steam is different! Its an illusion created by the shrinking of the fire gases as they cool....with correct application the steam is absorbed into the shrinking gases....there is a reduction in compartment pressure....no steam burns. You can feel the steam but the shrinking gases counter its expansion.
Firefighters need to adapt their own equipment in these simulators. Yes, there are two objectives in the containers -
1) Observe and learn about fire behaviour and fire gas formations/ignitions; and
2) Practise nozzle pulsing applications using 3D water-fog tactics to gas-cool.
You don't have to achieve both objectives as the 3D approach is not widely accepted (yet)!
It may be that the purpose your firefighters are entering a container is simply to learn about fire development. However, pulsing water-fog is a 'new-wave' approach that can save firefighter lives....it's NOT a substitute for smooth/straight stream....its a complementary tool that might save your bacon one day
10-14-2001, 05:23 PM #10
- Join Date
- Jun 2000
- MFD, New York
Hey Paul, do you have any ideas on how someone could train on using a 3D water fog that dosen't have access to a flash over trainer or even a burn tower? Could buildings that are going to be burned down at drills be used?
10-14-2001, 06:13 PM #11
Company40 - I first used 3D fog tactics in 1984 on 'live' fire in a 5 storey hotel where the stairshaft and a couple of rooms were alight. Before this I had NEVER entered a flashover can or had the opportunity to practise techniques in a training scenario - I was in at the deep end! The results impressed me enough to research this topic further!
Today I would strictly advise firefighters against such a practice and suggest that they learn fire behaviour in a setting similar to a flashover 'can'prior to advancing on to practise 3D techniques. It is important - ESSENTIAL - to learn how fire gases form and ignite first as this is what 3D firefighting is all about. Following on from this firefighters sould practise nozzle techniques in the open....outside! Pulse some bursts of a 30 degree angle fog-cone into the air and observe the 'hang-time' of your droplets. If they are fine enough they should suspend (falling) in air for 3-4 seconds. Get the feel of this 'pulsing' action before trying it on live fire. I can assure you, first attempts at pulsing nearly ALWAYS over-do it with too much water placed into the overhead. This allows water to reach hot surfaces and create a bit too much steam!
Taking this technique into the controlled conditions of a flashover 'can' is 'safe' and repeated evolutions are possible. However, taking this into real structures? I would say only those who are well versed in the techniques should do such a thing. I know it has been achieved in the UK, Sweden and Australia with great success but these were established research & training programmes that had gradually progressed to such settings.
Don't wanna dampen your enthusiasm brother but I would be wrong to say it would be safe to do such a thing without some training.
However, recently in Austin, Texas they DID take these techniques into real structures and 500 students practised 3D fog attack in 146 live training burns! Their conclusion was that this style of attack CAN be successful under certain conditions and should be taught to firefighters as a recognised form of attack.
10-15-2001, 08:48 AM #12
- Join Date
- Apr 2001
- Elkhart, IN, USA
Mr. Grimwood please email me about the 3D fog you speak of. I am not educated enough in this topic to effectively debate. I am not trying to turn this into a debate of sb/fog.
10-15-2001, 10:54 AM #13
jmichael - I appreciate you are not trying to but my own comments are sometimes taken as bait by the smooth .v. fog debate!!! I am a strong proponent of BOTH smooth AND fog but to be able to utilise the advantages of fog patterns in specific situations I am happy to propose combination nozzles as the ideal tool for th vas majority of interior firefighting scenarios.
I will e-mail you a paper on 3D - or alternatively it is available online at www.firetactics.com/FLASH-NZLE-TECHS-2000.htm
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