Car park fire Liverpool

[The Stationmaster]

  

With fires originating in vehicles and their various cargoes, couldn’t water sprinklers sometimes have the effect of throwing water on a chip-pan fire?

 

Water mist is rather different from directing a jet of water -it's more about containment rather than extinguishing the fire.

[62613]

  

With fires originating in vehicles and their various cargoes, couldn’t water sprinklers sometimes have the effect of throwing water on a chip-pan fire?

I remember, when doing my fire training for the MN, watching the firemen extinguish an oil fire with a water spray. If you do it correctly, it's fairly simple.

[giz]

If you go on the piece quoted in the Wobbly Bridges thread, it remarks that the towers did their job in standing up to the impact of a plane; it was the subsequent fire that weakened the structure

If I recall correctly, the basic failure mechanism was that the relatively lightweight floor trusses succumbed to the fire and therefore ceased to restrain the external columns at each floor level, resulting in the effective length of the columns increasing until they failed by buckling.

[jjb1970]

Hi-fog mist systems are excellent, they're very different from conventional water deluge systems. These days there is a wide range of fire suppressants (gas, liquid, powder), some of which were developed as safe and environmentally acceptable alternatives for CO2 after Halon was banned, such as Inergen. Some of the chemical suppressants which work by interrupting the chemical reactions of combustion are excellent. The problem is these systems are often quite expensive and they're sometimes targeted at very specific applications. For general building use a water deluge system is probably all you need, it is simple, robust, low maintenance and cheap (well, compared to the alternatives) and it doesn't asphyxiate people or get vented and lose all effectiveness in an open space.

[Jenny Emily]

If I recall correctly, the basic failure mechanism was that the relatively lightweight floor trusses succumbed to the fire and therefore ceased to restrain the external columns at each floor level, resulting in the effective length of the columns increasing until they failed by buckling.

I'd thought it was to do with the heating of the steel beams causing them to soften and eventually fail under the weight of the floors above. That's why the tower that was hit second collapsed first, because the plane hit much lower down so there was more weight of building above to cause the softened steel to fail.

[giz]

I'd thought it was to do with the heating of the steel beams causing them to soften and eventually fail under the weight of the floors above. That's why the tower that was hit second collapsed first, because the plane hit much lower down so there was more weight of building above to cause the softened steel to fail.

Yes the heat softened the thinner gauge steel of the floor support trusses causing them to fail. As the floors failed they no longer had any restraining effect on the vertical external columns, effectively making them longer and they buckled outwards under load. Of course, as they were also subjected to intense fire their strength would have also been affected. As you say, since the hit on the second tower was lower down, the columns had more load to carry and failed earlier.

[admiles]

"It was striking how little survived of the tractor units."

 

The cabs are GRP. I was watching a repeat of Highway Through Hell last night featuring the recovery of a burnt out American tractor unit that had been reduced to radiator core, engine block/gearbox, chassis frame and axles/wheels.

 

Most modern tractor unit cabs are steel or aluminium these days.

[Bernard Lamb]

 For general building use a water deluge system is probably all you need, it is simple, robust, low maintenance and cheap (well, compared to the alternatives) and it doesn't asphyxiate people or get vented and lose all effectiveness in an open space.

 

Reminds me of the case of the old church in Silvertown.

Pigeons used to roost in the roof and over the years the poop built up.

When the building caught fire the poop melted and by the time the fire brigade arrived the fire was almost out.

Bernard

[Edwin_m]

Yes the heat softened the thinner gauge steel of the floor support trusses causing them to fail. As the floors failed they no longer had any restraining effect on the vertical external columns, effectively making them longer and they buckled outwards under load. Of course, as they were also subjected to intense fire their strength would have also been affected. As you say, since the hit on the second tower was lower down, the columns had more load to carry and failed earlier.

I believe the reason for the heat softening was that the initial impact had badly damaged the heat-reistant coating that was sprayed onto the steel.  So it's possible that the towers would have survived either an impact without fire or a fire without impact.  As soon as one floor failed the impact of that pancaking down onto the floor below made that one fail too, even though less damaged, and so on down to the ground. 

[giz]

I believe the reason for the heat softening was that the initial impact had badly damaged the heat-reistant coating that was sprayed onto the steel.  So it's possible that the towers would have survived either an impact without fire or a fire without impact.  As soon as one floor failed the impact of that pancaking down onto the floor below made that one fail too, even though less damaged, and so on down to the ground. 

I did read that the fire break around the stairwell was basically a plasterboard partition which was destroyed in the impact, resulting in the people above being trapped. If there had just been a fire that would have been intact long enough for everyone to escape. You could also be correct about an intumescent coating to the steel being damaged.

[62613]

I believe the reason for the heat softening was that the initial impact had badly damaged the heat-reistant coating that was sprayed onto the steel.  So it's possible that the towers would have survived either an impact without fire or a fire without impact.  As soon as one floor failed the impact of that pancaking down onto the floor below made that one fail too, even though less damaged, and so on down to the ground. 

I've heard that too

[chriswright03]

The fire was so severe it melted the metal and the protective covering yet people from floors above managed to walk down past it?  Lot of stuff out there about it all but a lot needs quite a lot of salt..................................from both sides.  But we are way off topic now.

[PatB]

At the Dagenham town show many years ago (1980's?) the local police were demonstrating how dangerous a 'ringed' car could be. They had a Triumph Dolomite on show that looked in very good condition but was a death trap. The documentation was from an accident write-off but the only part of that car was from the back seat rearwards, the roof and the floorpan were from two other cars, stolen or wrecked but no identification marks. The front end and the mechanicals were from a stolen car. As I said it would have been a death trap, apart from a few tap welds it was held together by filler, the windscreen pillars were virtually all filler. I was told that even if it had hit a bump even at a moderate speed it would have disintegrated.

 

So pretty much the same structural integrity as any other 10+ year old British saloon of the time then .

[rockershovel]

I remember, when doing my fire training for the MN, watching the firemen extinguish an oil fire with a water spray. If you do it correctly, it's fairly simple.

There’s a similar exercise in the offshore training for the oil and gas sector, probably the same course?

[PhilJ W]

So pretty much the same structural integrity as any other 10+ year old British saloon of the time then .

It must have been earlier (1970's) then IIRC it was only two or three years old at the time on a K reg.

[duncan]

If a (say) car park has sprinklers to deluge the area, that in itself might pose an insurance problem - not sure if the usual "park at your own risk" get out clause would work, whether or not the system was correctly activated.  

 

As an aside, we don't have a sprinkler system at work, as a) the fire brigade would not enter our premises anyway, unless people were inside (quite rightly), b) the water would possibly cause flaming liquid to flow around & c) the water itself would do a lot of damage.

[34theletterbetweenB&D]

So pretty much the same structural integrity as any other 10+ year old British saloon of the time then .

 In my impoverished early career, a similarly financially challenged colleague had a Hillman Avenger on which the front seat passenger could feel the firewall moving relative to the floor pan. Came the day we were heading back to the office from an off site pint and an emergency stop was required for astray mother plus pushchair in road. I feared the worst as the brakes on this vehicle were pathetic, but it was a well integrated design and the small braking effort was enough to collapse the nearside front suspension, and the wreck thus elegantly turned so that the back end was nearly removed by a happily positioned lamp post bringing us to a halt, and no one got hurt.

[62613]

There’s a similar exercise in the offshore training for the oil and gas sector, probably the same course?

Mine was when I was a cadet in 1973, but yes, probably an updated version of it

[JeremyC]

There’s a similar exercise in the offshore training for the oil and gas sector, probably the same course?

From what what I was told by colleagues who had done them both the offshore fire course was much harder (I only ever did the MN one)