Water-mist/fog system to cool car - can this be used to put out a fire?

[H-viken]

Hi

The reason I am curious about this is that I work closely together with the technical department at a large ship owning company. Fire in the engine room onboard is one of our worst nightmares as they are very explosive. The main source of such a fire is oilmist.

To combat these fires the vessel has a CO2 system in the engine room. The problem is that it kills who ever is left in there, meaning that valuable time is lost getting people out before starting to put out the fire. What we have found is a lot more effective is a high pressure watermist system: it is harmless to people and equipment, plus it is extremely effective putting out these fires.

So my thought is - could we use this in our cars? If so, it is low cost, non-damaging to the equipment, environmentally friendly, and it leaves no residue like powder.

According to our techs it should be possible (even with a system using less than a quart of water).

Any thoughts?

/Johan

[davep]

If you are considering it as air conditioning, then I think it would be difficult. It would leave no residue only if it was distilled water (or equivalent), otherwise you get a fine salt fallout. Water evaporation will absorb a lot of heat, but it also increases humidity. I'm not sure how many pounds of water per hour would be required. A high pressure pump would be needed and a very fine nozzle.

[H-viken]

I would want to use it as a fire extinguisher in the engine bay and see several advantages over foam, powder, and gas, provided it is effective.

/Johan

[ejboyd5]

I trust that you are not re-inventing the wheel and going back to Lloyd Layman's WW II high pressure fog theories for fighting fires in confined spaces which were a certain way to steam boil any persons within. Are you using the water mist prior to ignition to alter the combustible range of the oil vapor or is it really being proposed as a firefighting agent?
Generally when a car fire gets going it is not from the ignition of a vapor, but rather from an electrical malfunction creating a heat source that transmits to its surroundings or from a frank spill of a flammable liquid that comes in contact with hot engine or exhaust components. Without more input, I don't see water mist as a viable supression agent in an automotive context.

[Frank Barrett]

Your vessel probably has a diesel engine. Your Porsche probably does not. Different rules apply to different fuel types.

Frank

[H-viken]

The vessels run on bunker (fuel oil). Which is marginally refined crude oil (agree, there is a difference depending on the burning medium).

In a Porsche - what causes fires most often: Oil leaks or fuel leaks? Onboard it is normally the bunker hitting a hot surface such as an exhaust pipe.

I am not convinced either that it works in a car, but thought it worth looking in to and interesting to discuss.

Ejboyd5, I am not familiar with the tests made in WWII, but fact remains that we use it onboard in confined spaces with great success.

/Johan

[Bummler]

Halon... If you can still get it.

[H-viken]

Halon... If you can still get it.

That would be great. But no can do - verboten in the EU.

/Johan

[docrodg]

Being a firefighter I can tell you that no water mist system is likely to work due to the fact that the amount of water needed to extinguish the fire is likely to be large and the mist system would have to put out enough gpm to actually extinguish. Add in the problem of petrochemicals spreadingand you get a big problem. In general the amount of water needed is gpm X time to extinguish=volume of fire area divided by 200 for normal combustibles. Fire systems in buildings are not meant to extinguish, just keep it from spreading quickly. Better would be a gas system such as CO2 or even better Halotron (which I believe is even approved for EU use). If water was to be used then AFFF would need to be added or better yet a CAFS system with AFFF used.

[H-viken]

Being a firefighter I can tell you that no water mist system is likely to work due to the fact that the amount of water needed to extinguish the fire is likely to be large and the mist system would have to put out enough gpm to actually extinguish. Add in the problem of petrochemicals spreadingand you get a big problem. In general the amount of water needed is gpm X time to extinguish=volume of fire area divided by 200 for normal combustibles. Fire systems in buildings are not meant to extinguish, just keep it from spreading quickly. Better would be a gas system such as CO2 or even better Halotron (which I believe is even approved for EU use). If water was to be used then AFFF would need to be added or better yet a CAFS system with AFFF used.

Thanks! I'll look in to Halotron (I know Halon is no longer allowed).

For those interested this is the system we use onboard; http://www.danfoss-semco.com/media/S...ing_System.pdf

It is extremely efficient when used on petrochemical fires. In our engine rooms we use tanks that are between 0,5-1 cubic metres in size. According to the Superintendents half a gallon should be plenty for an engine room in a car.

/Johan