3D Firefighting - Fog v Solid

[PaulGRIMWOOD]

Ok .... rules for posting here

1. Anyone can post a question and I will try my best to answer.
2. Your opinion counts
3. Any logical debate against current scientific knowledge can only be based on 'reliable' personal experience.
4 Recognise that this is NOT a general smooth-bore versus fog debate!

3D Water-fog will outperform a straight or solid stream when used to -

a) Effectively reduce temperatures in the overhead gas layers
b) Maintain (or even raise) the level of the smoke interface
c) Suppress volumes of gas-phase flaming combustion

It can be seen from tests undertaken on live fire that the 4-500 deg C 'spikes' created by bouncing 'pulsed' straight streams off the ceiling create excessive steam in comparison to the 150 deg C spikes on the thermocouple gradient created through 3D water-fog pulsing.

[RFDACM]

Paul could you possibly post the temperatures in Farenhiet for us US firefighters who cannot convert readily? This certainly will be interesting, I'm going to find so old clothes and goggles so the mud doesn't ruin my Sunday best!

[PaulGRIMWOOD]

Paul could you possibly post the temperatures in Farenhiet for us US firefighters who cannot convert readily? This certainly will be interesting, I'm going to find so old clothes and goggles so the mud doesn't ruin my Sunday best!

LMAO

Yes apologies ....

700 C = 1292 F
200 C = 392 F
500 C Spikes = 932 F spikes

600 C = 1112 F
450 C = 842 F
150 C spikes = 302 F spikes

[HalliganHook111]

The smoothbore cools the thermal layer from 1292 F to 392 F after a quick burst, and the fog mist only lowers it a few hundred degrees F. Am I reading that right? Also, you mentioned more steam was generated using the soild stream. Do you feel the steam generated from the SS would present a problem to firefighters or victims nearby?

[PaulGRIMWOOD]

Hey Halligan .... Yes that can be confusing. The bursts from the straight stream reduce temperatures in the overhead quite dramatically in comparison to the bursts from a fog pattern. However, remember this is just for a few short seconds.

Straight Stream More water hits the ceiling where greater evaporation occurs. A great deal of steam is created in the overhead and this shows on the gradients as a high cooling rate. However, the temperature quickly returns to its original level within a second or two. The effect briefly forces the smoke layer to descend.

3D Fog Bursts Hardly any water hits the ceiling and most of the evaporation occurs in the gas layer. This has the effect of contracting the gas layers .... the overhead gases shrink instead of expanding. This has the effect of raising the smoke layer.

As the process of gas cooling continues, the overhead gas temperatures cool faster and more effectively with a 3D fog pattern compared to a bursting or constant flow straight stream. The steam generated from the straight stream forced firefighters to vent the compartment or temporarily move back.

[PaulGRIMWOOD]

The evaporation of 3D water-fog has the effect of raising the smoke layer and maintaining thermal balance more effectively

[PaulGRIMWOOD]

The effects on the smoke layer of bursting straight streams at the ceiling ....

[chopper12]

I do not foresee this thread ending well.

[benson11]

Remember the old civil defense drills they taught it school in the 50s? "Duck and Cover" . Might be an ideal idea for this thread. LMAO!

[Dave1983]

Paul...I tip my hat for your continued efforts, but I think its a loosing battle. Firefighters here are a hard-headed bunch (if you didnt figure that out already).

[jlcooke3]

First off I want to make sure I get this straight in my head:

1.) 3D fog reduces the overall temp. of the upper gaseous layer for longer periods of time than solid streams or straight streams that are pulsed into the upper gaseous layer. Correct?

2.) Due to the cooling and contraction of the gases in the thermal layer the smoke actually rises when 3D fog attack is used, or at least doesn't bank down. Correct?

[PaulGRIMWOOD]

Dave I was a firefighter in the US for two years and I appreciate what you are saying. I also appreciate that forum posters here are likely to take every opportunity to rebuke what i am attempting to say. However, if we can keep the debate relevant .... to the point .... informed .... based on valid facts or experience .... then maybe we can all learn something.

I am not debating from the stance that 'my way is better than yours' and neither should anyone else be. This debate should keep to reasoned opinions or hard facts. If I suggest that firefighters are poorly trained in specific subjects and that this lack of training might be causing LODDs that is not meant as a personal attack on anybody. We are ALL facing the same hazards on a day to day basis and any attempt to improve firefighter safety and efficiency should be welcomed.

If systems of work appear too complex to take onto the fire-ground then let us analyse this belief. This thread is NOT about about High Pressure Fog! It is NOT about smooth-bore versus fog! I am so far simply stating research that supports my practical experience of 35 years. If you want to discuss this research, or the techniques behind it, now is your chance.

I have a hard head too!

[PaulGRIMWOOD]

First off I want to make sure I get this straight in my head:

1.) 3D fog reduces the overall temp. of the upper gaseous layer for longer periods of time than solid streams or straight streams that are pulsed into the upper gaseous layer. Correct?

No not quite .... 3D fog reduces the temperatures in the overhead with less disruption of the gas and smoke layer. The cooling process in a compartment is more gradual .... much less steam. It takes several nozzle bursts to achieve this but over a few minutes the cooling effect is much greater than with a straight stream used in the same way..

2.) Due to the cooling and contraction of the gases in the thermal layer the smoke actually rises when 3D fog attack is used, or at least doesn't bank down. Correct?

Quite correct.

Here is a classic fire gas layer that is in need of some 3D bursts of water fog before the main fire is taken .... it is a natural approach that would be taken as you advance up the stair-shaft.

[don120]

No not quite .... 3D fog reduces the temperatures in the overhead with less disruption of the gas and smoke layer. The cooling process in a compartment is more gradual .... much less steam. It takes several nozzle bursts to achieve this but over a few minutes the cooling effect is much greater than with a straight stream used in the same way..



Quite correct.

And during these "few" minutes and multiple 3D fog bursts is the fire
not still burning and spreading and producing more and more hot gases?

Don

[jlcooke3]

Ok, I believe I have the jist of it.

Question: 1.) Under what circumstances are you advocating that 3D Fog is better than solid stream?

[PaulGRIMWOOD]

And during these "few" minutes and multiple 3D fog bursts is the fire
not still burning and spreading and producing more and more hot gases?

Don

Don .... your point is important here. Once the base of the fire can be attacked then a straight stream should be used. The use of 3D fog bursts are reserved for the approach to a fire (see above example). In this case you would be in position to apply 3D fog bursts as you advance up the stairs, just before taking the main fire room.

[PaulGRIMWOOD]

Ok, I believe I have the jist of it.

Question: 1.) Under what circumstances are you advocating that 3D Fog is better than solid stream?

Cooling the gas layers on the approach routes to a fire .... in smoke filled environments ... in corridors .... in adjacent rooms where hot fire gas layers are transporting .... in stairshafts (esp where a burning gas layer exists) .... where a room is bordering on flashover with flaming in the overhead but you haven't located the base of the fire or the main fuel fire. Also to test the heat in the overhead .... burst a straight stream directly above your head and you'll get a lot of water dropping back down whatever the temperature in the overhead right? Do it with a fog pattern (just a brief burst) and the fall back will effectively guide you as to the temperature above your head! If its near flashover you won't see ANY drop back!

[jlcooke3]

Cooling the gas layers on the approach routes to a fire .... in smoke filled environments ... in corridors .... in adjacent rooms where hot fire gas layers are transporting .... in stairshafts (esp where a burning gas layer exists) ....

Doesn't proper and effective ventilation of a fire building do the same thing?

where a room is bordering on flashover with flaming in the overhead but you haven't located the base of the fire or the main fuel fire.

A straight stream or solid stream into the overhead area will do the same thing when properly applied. In my expierence, which is not vast but non the less valid, properly apllied short burst of a straight stream or solid stream into the fire gas layer causes little if any thermal layer imbalance, significantly cools the area, does not cause a significant banking down of smoke. I will state for the record that I have never used or trained in 3D Water Fog techniques.

[PaulGRIMWOOD]

Doesn't proper and effective ventilation of a fire building do the same thing?

You tell me! Are you honestly saying that ALL the smoke and dangerous gases clear from a structure as soon as you vent? Of course correctly applied venting will assist but if the fire is not immediately located the burn rate and smoke production will increase.

A straight stream or solid stream into the overhead area will do the same thing when properly applied. In my expierence, which is not vast but non the less valid, properly apllied short burst of a straight stream or solid stream into the fire gas layer causes little if any thermal layer imbalance, significantly cools the area, does not cause a significant banking down of smoke. I will state for the record that I have never used or trained in 3D Water Fog techniques.

OK .... but 3D fog does it more effectively. Now if you don't see drops in the smoke layer or feel steam when bursting a straight stream then maybe the temperature in the overhead is not hot enough to create these effects? I have repeatedly done this in live burns and live fires over a 20 year period. I can repeat the effects for demonstration. If you don't see steam or smoke layers descending when bursting the straight stream .... try it in a room bordering flashover or with a temperature around 1000 F at the ceiling? I am interested in your views in this respect and accept what you say. I am interested in the reasons why you don't see the same as me though?

[jlcooke3]

You tell me! Are you honestly saying that ALL the smoke and dangerous gases clear from a structure as soon as you vent?

Nope, not at all. I think everyone knows that while proper ventilation has immediate effects, I don't believe anyone is delusional enough to believe that the effects of ventilation are instantaneous. In the same regard though, are you saying that your tactic of 3D Water Fog immediatley renders the fire gas layer inert and stops the burning process? No I don't believe so. I believe that ventilation and 3D Water Fog accomplish the same thing by using two different methods.

I am interested in the reasons why you don't see the same as me though?

See what the same, that 3D Water Fog does it better or the smoke banking down and descending steam? I didn't state that there was no banking of smoke or steam production I stated that it was minimal when properly applied.