Comparing Water and Ice Melting for fighting fires

[cptolemy]

Good morning,

I'm wondering on this question for a while. Imagine we have a fire progressing in a corridor 30 meters wide at a known velocity. What kind of barrier (of the following) can be most successful in minimizing or even erasing this fire and why: a water-soaked area, or a zone covered with crushed ice (half a centimeter height for instance)? Or the effect will be the same?

Weird question I know, but I would very much like to hear your thoughts.

Kind regards

Ptolemy

 

[phinds]

Good morning,

I'm wondering on this question for a while. Imagine we have a fire progressing in a corridor 30 meters wide at a known velocity. What kind of barrier (of the following) can be most successful in minimizing or even erasing this fire and why: a water-soaked area, or a zone covered with crushed ice (half a centimeter height for instance)? Or the effect will be the same?

Weird question I know, but I would very much like to hear your thoughts.

Kind regards

Ptolemy

What do you think it would be and why?

 

[cptolemy]

Hi

I'm exactly collecting opinions.

I know that the water and ice evaporates at the same speed (I've read a specialized report about it).
But I cannot predict with the advance of the fire towards both situations, if one can be more efficient or not - probably they are the same. But I believe that the ice properly placed (like a ramp) could be (hip.) more efficient.

This is not an exam quiz test by the way. It's a real doubt, for a potential serious problem. Thus, I'm asking the experts.

Clear skies

Ptolemy

 

[berkeman]

What kind of fire? What exactly in the corridor is on fire? Are you familiar with the Fire Triangle? How much Fire Science have you studied? Can you Upload a PDF or JPEG sketch of your ice-related scheme?

https://upload.wikimedia.org/wikipe...Fire_triangle.svg/220px-Fire_triangle.svg.png

 

[anorlunda]

This is not an exam quiz test by the way. It's a real doubt, for a potential serious problem. Thus, I'm asking the experts.

If you want to make a fire barrier, you need to be a lot more specific before engineers can give qualified opinions.

Dimensions, duration, temperatures, volume on each side. Comparisons with other fire retardant systems.

 

[cptolemy]

Hi

Well, I was placing an hipothetical case, since in fires all is almost unpredictable. I was speaking of the unpredictable fire fronts, which killed, for instance, hundreds of people here in Portugal, in my own country, in Pedrogão last year (sufocated and burned alive). So actually, maybe if I ressurect them, they can give you gentlemen the accurate and precise information?... Like how long they spent dying? From what direction was the wind blowing? The flames velocity? Perhaps the accelaration?...

Oh, and another thing: I have a PHD in Math/Applyed Physics (variant astronomy) so don't patronize me. But I'm not an engineer, so I assume my ignorance in that department. Even with a Phd, I ask when I don't know or when I have doubts - it's called being humble (your familiar with the word, but most important, the meaning?). If this hipotetical data is not enough for an example - even if a simple one - instead of childish sarcasm, we are done. And if no one really can understand what I asked, and place an hipotetical case...well, go back to school, ok? Just my honest 2 cents.

Regards

Ptolemy.

 

[berkeman]

I was speaking of the unpredictable fire fronts, which killed, for instance, hundreds of people here in Portugal, in my own country, in Pedrogão last year (sufocated and burned alive).

So you are asking about forest fires? Or building fires? They are fought very differently and with different materials.

If this hipotetical data is not enough for an example - even if a simple one - instead of childish sarcasm, we are done. And if no one really can understand what I asked, and place an hipotetical case...well, go back to school, ok? Just my honest 2 cents.

I'm certainly not meaning to be patronizing or insulting. I do have a background in basic Fire Science (I work part time in EMS, and work closely with friends in the local Fire Departments). Hence my questions trying to understand your background.

 

[cptolemy]

Hi Berkeman,

Ok, I apologise... It's just I'm developing a prototype that might help (not solve) in some heavy and violent forest fires. We lost big last year. And dispite the efforts of hundreds of men, dispite the most brilliant minds, the best known resources (even from France, Spain, etc.), we just...lost. And we saw those losses.

What I'm trying to establish is, if in a uncontroled fire (in a forest for instance) I need to contain a front, let's say of 30 meters (to 100, let's say) which advances towards a village (so I assume that direction will sustain for 10 minutes for instance without wind changes), is it more efficient to use a wide a water-soaked area (or dig small channels in the ground - if there's time), or if a zone covered with crushed ice would work more effiently. Since my prototype needs time, I'm searching the most efficient (and less expensive - since tons are needed) material that would work.

Just that.

Regards

Ptolemy

 

[CWatters]

I think you would have to do the experiment. I think I could argue it both ways...

The latent heat of melting favours ice but Ice might fall off the ceiling/trees leaving it/them dry, (or at least less wet than one soaked in water.).

 

[cptolemy]

Hi

Yes, it was my idea also. But that latent heat was the first thing that make me think about it. I didn't do, however, any test. In the same scenario, imagine a ground "band" of 5 meters by 50 m in front of the coming fire just wet by water (what fireman usually try to do so the fire won't spread), and the same belt covered by ice. Wouldn't the second be more efficient in delaying the fire?...

Regards

 

[berkeman]

It is certainly a noble and worthwhile thing to explore. I live in Northern California, and our wildfires have been especially bad the past few years, with many deaths and billions of dollars of damage. I have several friends who are wildland firefighters, and I know many of our local firefighters who are assigned to temporary "Strike Teams" who drive to the fires in their engines and serve for a couple weeks at a time. Rough duty!

What I'm trying to establish is, if in a uncontroled fire (in a forest for instance) I need to contain a front, let's say of 30 meters (to 100, let's say) which advances towards a village (so I assume that direction will sustain for 10 minutes for instance without wind changes), is it more efficient to use a wide a water-soaked area (or dig small channels in the ground - if there's time), or if a zone covered with crushed ice would work more effiently. Since my prototype needs time, I'm searching the most efficient (and less expensive - since tons are needed) material that would work.

I think it's worth exploring, especially in connection with other fire suppressant materials. Keep in mind that air drops are the typical way that such suppressants are dropped ahead of the advancing fire (or on hot spots in some cases), so the density of the material (weight per unit area covered on the ground) is an important measure of effectiveness.

I'm guessing that the complications of making the tons of ice for air drops, and the fact that the ice will melt on the ground before the advancing fire front reaches it, will probably be the reasons that ice isn't used currently and may not work any better than water. I think the state of the art is currently dry fire suppressant powder, in combination with smaller water drops on hot spots by helicopter. This introductory article at Wikipedia looks fairly good, although more directed Google searches may help to shed light on the ice option...

https://en.wikipedia.org/wiki/Wildfire_suppression

https://upload.wikimedia.org/wikipedia/commons/thumb/2/20/BLM_Firefighting_at_Pine_Mountain,_Oregon_(14186496134).jpg/300px-BLM_Firefighting_at_Pine_Mountain,_Oregon_(14186496134).jpg

 

[berkeman]

BTW, I was talking with a Battalion Chief friend of mine recently at my local fire station, and he asked me if I had ever seen the daily briefing maps that are printed out each day at the Incident Command Center of a typical wildland fire. I told him that I hadn't seen any, and since he had just gotten back from Strike Team duty for a recent wildland fire (where he was part of the Incident Command Staff), he opened the back of his Tahoe and pulled out some of the maps they had been using.

Turns out they have large format color printers running on the generators at the Incident Command Center, and each morning they print out the situation maps for the Command Staff to use in the planning for that day's operations. Pretty amazing stuff, especially when you consider what it takes to coordinate hundreds of firefighters and dozens of aircraft all in the same relatively small area. And to do it in the best possible way to protect life and then structures. Hats off to such amazing teamwork.

This is not one of his maps; his were similar to this, but zoomed in Topographical maps with lots more details on the terrain and the fire(s)...

https://www.facebook.com/ShastaTrin...994429865937/2236994326532614/?type=3&theater

 

[some bloke]

I've not got any official accreditation on the sunject, but my thoughts would be that it depends greatly on the temperature of the fire. Water prevents fire by both smothering and cooling the fuel - preventing oxygen from reaching it. If you had crushed ice, but the fire was hot enough to evaporate the surface film of water before it had a chance to make contact with the fuel, then it will not make it as wet as just water. You will also have to consider the increased surface area of the ice compared to the forest floor, as if the crushed ice has a greater surface area, it will melt & evaporate quicker than just a wet floor.

The ice will only work if it melts and subsequently makes the fuel wet, I think. If the fire is fierce enough to evaporate the ice as it melts, then it will not have a very good effect.

You aim, I take I, is to prevent a forest fire from sweeping into a village? Are you aiming to give enough time for the village to be evacuated, or to actually halt the fire to the point where it burns itself out?

Fire breaks would be a good way to start - lines of deforestation designed to prevent the fire from having anywhere to spread. Natural barriers like lakes and rivers and their artificial counterparts like canals and moats would also be a good thing to investigate. I suspect that a permanent feature will be a more useful method than something like ice - you would need a lot of ice, and it would have to be on standby all the time, using up energy to keep it frozen (I'm assuming the forest fires are typically in the heat of summer). Then you will need a method of delivery for the ice. If you're talking about a 10 minute window, that will mean every village will need their own system, there wouldn't be time for one to be delivered.

You might be able to use some sort of chilled hose to pump a slush out, but I suspect that water would be a lot easier to manage than ice, from a strictly practical point of view. You also need to think how warm the ground will be on which it sits - it could be that the ice will simply melt before the fire even gets there.

I don't know how it would react to fire, so someone else will have to weigh in on this, but could you mix dry-ice (CO2) with regular ice to maintain the low temperatures? The dry ice would also help to suffocate the flames, as it would melt into Carbon Dioxide ,which is used in fire extinguishers.

Disclaimer - As at the start of the post, I'm not qualified in fire fighting, so please get further advice before following my ideas!

 

[sophiecentaur]

There are many practicalities that would detract from possible advantages from using ice - you would need to produce it or have a handy local source.
One thing in favour of ice could be the fact that it would be easier, perhaps, to project it a great height or long distance in small chunks (ballistic delivery) than pumping water could achieve. But there could be problems getting to so stay in some places where water would do naturally.
The specific application would need to be know, as others have pointed out.

 

[cptolemy]

Hi

Thanks for the replies. They are very helpull, really. I was not thinking on using ice cubes as we know it (taken from the freze - I apologise for any confusion), but a kind of crushed ice - like the slush of a plain tequila (I don't know if you ever saw it). That is, an optimized granulated volume. So it would be light, and easy to carry. It could not be very thin, neither too "huge" as an ice cube. So it would melt with a controlled time. This kind of ice is easely done and tranported.

But some remarks here are giving me some ideas. And yes, the idea would be to delay, or restrain the path of the fire - thus controling where it would go (in preference to the nearest river...which is improbable) or make it circle itself (once there was no more to burn, the fire would extinguesh by itself, not for lack of O2 but lack of material to burn, its "fuel"). This would only work in certain kind of terrains of course. Not in forests, or places where a leaf on fire could go in the wind and reach a tree or bush across the secured ground area spreading the fire.

Kind regards

(and thanks - sincerely)

 

[CWatters]

I was in the south of France during a forest fire. I think one of the big problems is getting enough water to the site of a fire. That time they used seaplanes to scoop up seawater without landing, then fly to the fire, drop and repeat. Two or three planes flew continuously overhead for most of the day without containing the fire.

It would need a tremendous a mount of power to freeze enough water fast enough.

 

[cptolemy]

Hi CWaters

The granulated ice would be in containers - but it was one idea only.

Yes, you are correct about the planes tactics. The problem - which happened here in Portugal - was at one time the smoke was so intense that pilots didn't saw nothing, and the flames were so high that they had - to make things worst - fligh even higher (for their security) and the results were largely compromised. Another terrible factor was that winds were worst at night when the planes could not do anything.

So, we lost.

Regards

Ptolemy

 

[LURCH]

I had thought of a similar approach, using dry ice in snow machines, like the kind used to make a layer of snow for a ski resort. But my idea was related to oil well fires. One problem with the current idea is that forest fires tend to spread mostly along the tree tops, and not the ground. So ice on the ground is unlikely to stop the fire. Even shaved ice dropped from planes would tend to fall right through the tree tops without getting them very wet.

A large line of dry ice dropped behind the fire front would sublimate quickly from the heat, and get pulled into the fire by the same winds that are propelling the fire front. But the quantity needed would probably make that impractical. Still, some form of retardant sprayed into the air and carried by the wind might be of some benefit, allowing firefighters to attack from behind the fire, where it is much safer, and the wind is actually helping rather than hindering.

That’s just brainstorming, of course, but if others can build on the concept, maybe something useful could come of it.

 

[256bits]

Hi CWaters

The granulated ice would be in containers - but it was one idea only.

Yes, you are correct about the planes tactics. The problem - which happened here in Portugal - was at one time the smoke was so intense that pilots didn't saw nothing, and the flames were so high that they had - to make things worst - fligh even higher (for their security) and the results were largely compromised. Another terrible factor was that winds were worst at night when the planes could not do anything.

So, we lost.

Regards

Ptolemy

The extent of the fire was extreme.
It was uncontrollable for several days, and even suffered a 'downdraft' at one point that exposed a large area to heat and fire.
Progress of the fire front was km per hour and that was impossible to confront head on.
Only fringe areas could be combatted.

See here for the timeline of the fire in 2018.
http://www.portugalwildfires.com/pedrogao-grande-fire-timeline/

from
http://www.portugalwildfires.com/
for more information.

 

[sophiecentaur]

Even in disaster situations, the COST of dealing with the event would govern the choice of strategy. A refrigeration plant would be expensive to make and to run and I have a feeling that hiring and running more aircraft would be cheaper and allow a more effective response. That would apply in most situations but there could always be fires where ice could have its place.
Building design is responsible for the way many fires spread. I heard that the construction of the Twin Towers was largely responsible for the way the buildings behaved after the aircraft strikes and the magnitude of the Grenfell Tower disaster in the UK was entirely due to a bad design and cost cutting by the authorities.
Local politics has a large share of blame for the long term vulnerability of buildings and even forests. They get our votes on the basis of low taxes and it's only taxes that can pay for regulation and public works.

 

[Vanadium 50]

This whole thread is based on the idea that water stops fire primarily by cooling it. Except for very small fires (mass of item burning << mass of water), this is not the case. Water works primarily by smothering. Ice pellets with gaps between them will be less effective at smothering than liquid.

 

[PeterO]

Hi

Yes, it was my idea also. But that latent heat was the first thing that make me think about it. I didn't do, however, any test. In the same scenario, imagine a ground "band" of 5 meters by 50 m in front of the coming fire just wet by water (what fireman usually try to do so the fire won't spread), and the same belt covered by ice. Wouldn't the second be more efficient in delaying the fire?...

Regards

Any advantage of using ice vs water may be negated by the ability to transport the ice, rather than water, to the deployment location, and then distributing it once you get it there.
As one other responder said, easy to cover a tree/structure with water - very difficult to cover it with ice.

 

[pedro the swift]

Greetings,
Don't know about using ice to fight fires but I had a idea some time ago(Ii do have them sometimes) that a possible way of fire fighting is to use dirt, Thinking mainly of bush fires and places where water is scarce.
My idea was to use some kind of machinery to project a large quantity of dirt or soil etc onto the fire to smother it. Maybe a high speed mobile conveyor and a system to feed dirt/soil onto it. Material could be scooped up locally in the bush by dozers etc. The conveyor should be able to project the dirt a fair distance, be easily moved across the flame front. I guess it would only be useable from bush tracks or trails and in suitable terrain.

 

[berkeman]

Greetings,
Don't know about using ice to fight fires but I had a idea some time ago(Ii do have them sometimes) that a possible way of fire fighting is to use dirt, Thinking mainly of bush fires and places where water is scarce.
My idea was to use some kind of machinery to project a large quantity of dirt or soil etc onto the fire to smother it. Maybe a high speed mobile conveyor and a system to feed dirt/soil onto it. Material could be scooped up locally in the bush by dozers etc. The conveyor should be able to project the dirt a fair distance, be easily moved across the flame front. I guess it would only be useable from bush tracks or trails and in suitable terrain.

Dirt is used on small scales to fight wildfires, but any large-scale use of dirt would require the digging/projecting apparatus to be way too close to the flame front on the ground. And given the speed of advance of many wildfires, that's a very dangerous place to be! That's why so much of the firefighting is done with planes and helicopters...

EDIT: Hey -- check this out. I did a quick search, and there are some situations where your idea is being used!

https://wildfiretoday.com/2011/07/04/dirt-throwing-machine/

 

[LURCH]

Air drops seem to be the most effective tool when fighting wildfires. The tragic example mentioned by the OP sounds like it was partly caused by the grounding of air support. Perhaps the greatest contributions could be made by expanding aerial capabilities.

If the air drops were being performed by very large drones, the restrictions could be relaxed a bit regarding the conditions under which they are allowed to fly. Improved sensors on board, together with better networking of information from all sources, would make the flying much safer, and the delivery more accurate.

NOw that I think of it, people are probably working on both of those ideas already. I am going to search around a little and see if I can come back with some information.

 

[LURCH]

Ok, that didn’t take long.
NBC News:
https://www.nbcnews.com/mach/amp/ncna820966
CNET:
https://www.cnet.com/google-amp/news/californias-fires-face-a-new-high-tech-foe-drones/
Fortune:
http://amp.timeinc.net/fortune/2018/11/29/drones-wildfires-california-drones
And this one from Fox News is exactly what I was thinking:
https://www.google.com/search?clien.....0...1...0i71j33i22i29i30j33i160.8Qq9_JwL3Kc

A lot more results. Many agencies are working on this, with some of them putting real fire-fighting drones in the air within the year (drones for surveillance of fires are already in use).

Problem with this, of course, is that it will be some time before this tech is widely available.

 

[pedro the swift]

They "stole" my idea about the dirt thrower! I knew I should have patented it!

 

[256bits]

A lot more results. Many agencies are working on this, with some of them putting real fire-fighting drones in the air within the year (drones for surveillance of fires are already in use).

The lack of drones isn't the problem - it can crash the same as a pilot controlled plane.
The air currents close to and above the fire are the problem.

Keeping an aircraft airborne - someone has to make a decisions regarding safety and effectiveness of deploying water bombers ( as well as ground crew ).
The water bomber has to be able to get low so that the drop of water does not dissipate before reaching the target. For an aggressive fire, that is difficult to do.
The fire in question was so aggressive that it was unsafe for people as well as machinery to be close to the fire front either on the ground or in the air.
The decision to ground the aircraft was done for safety reasons, as well as that the water drops from a height that would be flyable would imprint on dousing of the fire. - the water would evaporate before hitting the ground.
See post 19 for a review of the fire in question.
We are not talking 100's of feet, but thousands, even tens of thousands for safe flying. for an aggressive fire.