Trench effect - Revision history

Editor at 08:03, 27 June 2025

2025-06-27T08:03:30Z

← Older revision		Revision as of 08:03, 27 June 2025
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	* Approved Document B: Fire Safety. New enhanced fire safety updates.		* Approved Document B: Fire Safety. New enhanced fire safety updates.
	* Arcing.		* Arcing.
		+	* BS 476.
	* Building Safety Act.		* Building Safety Act.
	* Coanda effect.		* Coanda effect.

Editor at 07:52, 27 June 2025

2025-06-27T07:52:42Z

← Older revision		Revision as of 07:52, 27 June 2025
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	* Approved document B.		* Approved document B.
		+	* Approved Document B: Fire Safety. New enhanced fire safety updates.
	* Arcing.		* Arcing.
	* Building Safety Act.		* Building Safety Act.
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	* Ionisation smoke alarm.		* Ionisation smoke alarm.
	* Joint fire code.		* Joint fire code.
		+	* Material of limited combustibility.
	* Means of escape.		* Means of escape.
	* Optical smoke alarm.		* Optical smoke alarm.
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	* Smoke.		* Smoke.
	* Spontaneous ignition temperature.		* Spontaneous ignition temperature.
		+	* Timber and Fire Safety.
	* Wet riser.		* Wet riser.

	[[Category:Articles_needing_more_work]] [[Category:Building_safety]]		[[Category:Articles_needing_more_work]] [[Category:Building_safety]]

Editor at 05:58, 27 June 2025

2025-06-27T05:58:54Z

← Older revision		Revision as of 05:58, 27 June 2025
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−	The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: the coanda effect from fluid dynamics and the concept of flashover from ~~teh~~ physics of fire behaviour.	+	The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: the coanda effect from fluid dynamics and the concept of flashover from the physics of fire behaviour.

	The coanda effect refers to the tendency of a fast-moving stream of gas to curve toward and cling to nearby surfaces. As the stream moves, its static pressure drops, creating a pressure difference that pulls it toward the surface and keeps it attached. In the case of fire spread this refers to where rather than moving directly vertically in a fire gases may move toward and cling to nearby surfaces such as external walls.		The coanda effect refers to the tendency of a fast-moving stream of gas to curve toward and cling to nearby surfaces. As the stream moves, its static pressure drops, creating a pressure difference that pulls it toward the surface and keeps it attached. In the case of fire spread this refers to where rather than moving directly vertically in a fire gases may move toward and cling to nearby surfaces such as external walls.
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	* Arcing.		* Arcing.
	* Building Safety Act.		* Building Safety Act.
		+	* Coanda effect.
	* Combustibility.		* Combustibility.
	* Dry riser.		* Dry riser.
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	* Fire in buildings.		* Fire in buildings.
	* Fire inspector.		* Fire inspector.
		+	* Fire point.
	* Fire resistance.		* Fire resistance.
	* Fire retardant.		* Fire retardant.
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	* Fire spread.		* Fire spread.
	* Fire stopping.		* Fire stopping.
		+	* Flash point.
		+	* Flashover.
	* Grenfell Tower fire.		* Grenfell Tower fire.
	* Ionisation smoke alarm.		* Ionisation smoke alarm.
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	* Protected lobby.		* Protected lobby.
	* Smoke.		* Smoke.
		+	* Spontaneous ignition temperature.
	* Wet riser.		* Wet riser.

	[[Category:Articles_needing_more_work]] [[Category:Building_safety]]		[[Category:Articles_needing_more_work]] [[Category:Building_safety]]

Editor at 05:56, 27 June 2025

2025-06-27T05:56:30Z

← Older revision		Revision as of 05:56, 27 June 2025
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	For detailed information about the trench effect see "[https://publications.iafss.org/publications/fss/5/225/view/fss_5-225.pdf Fires in Inclined Trenches: the Effects of Trench and Burner Geometry on the Critical Angle]" by PJ. Woodburn and D.D.Drysdale		For detailed information about the trench effect see "[https://publications.iafss.org/publications/fss/5/225/view/fss_5-225.pdf Fires in Inclined Trenches: the Effects of Trench and Burner Geometry on the Critical Angle]" by PJ. Woodburn and D.D.Drysdale
		+
		+	= Related articles on Designing Buildings =
		+
		+	* Approved document B.
		+	* Arcing.
		+	* Building Safety Act.
		+	* Combustibility.
		+	* Dry riser.
		+	* External fire spread, Supplementary guidance to BR 187 incorporating probabilistic and time-based approaches.
		+	* External fire spread: building separation and boundary distances (BR 187).
		+	* Fire blanket.
		+	* Fire damper.
		+	* Fire detector.
		+	* Fire door.
		+	* Fire extinguisher.
		+	* Fire in buildings.
		+	* Fire inspector.
		+	* Fire resistance.
		+	* Fire retardant.
		+	* Fire Safety Act.
		+	* Fire safety information.
		+	* Fire (Scotland) Act 2005.
		+	* Fire Safety Requirements for Buildings.
		+	* Fire spread.
		+	* Fire stopping.
		+	* Grenfell Tower fire.
		+	* Ionisation smoke alarm.
		+	* Joint fire code.
		+	* Means of escape.
		+	* Optical smoke alarm.
		+	* Protected escape route.
		+	* Protected lobby.
		+	* Smoke.
		+	* Wet riser.

	[[Category:Articles_needing_more_work]] [[Category:Building_safety]]		[[Category:Articles_needing_more_work]] [[Category:Building_safety]]

Editor at 10:10, 25 June 2025

2025-06-25T10:10:53Z

← Older revision		Revision as of 10:10, 25 June 2025
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	As a scenario a fire burning next to a steep slope causes the flames to follow the surface (coanda effect ), the flames heat the material further upslope, which with the heat emit flammable gases and ignite creating a flashover. The new flames, from the flashover in turn, follow the slope, creating more gases and rapid spread of fire, continuing upward until the any available fuel is exhausted.		As a scenario a fire burning next to a steep slope causes the flames to follow the surface (coanda effect ), the flames heat the material further upslope, which with the heat emit flammable gases and ignite creating a flashover. The new flames, from the flashover in turn, follow the slope, creating more gases and rapid spread of fire, continuing upward until the any available fuel is exhausted.

−	A particular case in point example of the trench effect occurring with tragic consequences was the King’s Cross Underground fire on 18 November, 1987, which claimed 31 lives and injured commuters and emergency personnel. Initially the fire was judged as manageable, but the fire unexpectedly intensified, rapidly spreading up a wooden escalator and into the ticket hall. The post-incident investigations identified the trench effect as a key factor in the escalation of the fire. As the flames and hot gases were funnelled beneath the escalator the fire rapidly intensified as it went up to the hall space of the station. The fire was studied with experimental scale models and computer simulations, which revealed how fire dynamics in trench-like structures encourage this phenomenon and can lead to sudden, catastrophic flare-ups, particularly significant and of danger when occurring in confined spaces such as was the case with the Kings Cross fire.	+	A particular case in point example of the trench effect occurring with tragic consequences was the [https://www.railwaysarchive.co.uk/docsummary.php?docID=75 King’s Cross Underground fire on 18 November, 1987], which claimed 31 lives and injured commuters and emergency personnel. Initially the fire was judged as manageable, but the fire unexpectedly intensified, rapidly spreading up a wooden escalator and into the ticket hall. The post-incident investigations identified the trench effect as a key factor in the escalation of the fire. As the flames and hot gases were funnelled beneath the escalator the fire rapidly intensified as it went up to the hall space of the station. The fire was studied with experimental scale models and computer simulations, which revealed how fire dynamics in trench-like structures encourage this phenomenon and can lead to sudden, catastrophic flare-ups, particularly significant and of danger when occurring in confined spaces such as was the case with the Kings Cross fire.

−	[[Category:Articles_needing_more_work]]	+	For detailed information about the trench effect see "[https://publications.iafss.org/publications/fss/5/225/view/fss_5-225.pdf Fires in Inclined Trenches: the Effects of Trench and Burner Geometry on the Critical Angle]" by PJ. Woodburn and D.D.Drysdale
		+
		+	[[Category:Articles_needing_more_work]] [[Category:Building_safety]]

Editor at 10:05, 25 June 2025

2025-06-25T10:05:46Z

← Older revision		Revision as of 10:05, 25 June 2025
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	Flashover is a sudden, intense ignition of all combustible materials in a space. It occurs when surfaces become so hot that they release flammable gases, which spontaneously ignite once they reach a critical temperature. Prior to flashover, these gases may be present but remain too cool to ignite.		Flashover is a sudden, intense ignition of all combustible materials in a space. It occurs when surfaces become so hot that they release flammable gases, which spontaneously ignite once they reach a critical temperature. Prior to flashover, these gases may be present but remain too cool to ignite.

−	As ~~an example of the trench effect, impacted by the coanda effect could be~~ a fire burning next to a steep slope causes the flames to follow the ~~surface—an example of the~~ coanda effect ~~in action. As~~ the flames heat the material further upslope, ~~it begins to~~ emit flammable gases ~~that eventually~~ ignite in a flashover. The new flames, in turn, follow the slope, ~~feeding a jet~~ of fire ~~that continues up the incline~~ until the available fuel is exhausted.	+	As a scenario a fire burning next to a steep slope causes the flames to follow the surface (coanda effect ), the flames heat the material further upslope, which with the heat emit flammable gases and ignite creating a flashover. The new flames, from the flashover in turn, follow the slope, creating more gases and rapid spread of fire, continuing upward until the any available fuel is exhausted.
		+
		+	A particular case in point example of the trench effect occurring with tragic consequences was the King’s Cross Underground fire on 18 November, 1987, which claimed 31 lives and injured commuters and emergency personnel. Initially the fire was judged as manageable, but the fire unexpectedly intensified, rapidly spreading up a wooden escalator and into the ticket hall. The post-incident investigations identified the trench effect as a key factor in the escalation of the fire. As the flames and hot gases were funnelled beneath the escalator the fire rapidly intensified as it went up to the hall space of the station. The fire was studied with experimental scale models and computer simulations, which revealed how fire dynamics in trench-like structures encourage this phenomenon and can lead to sudden, catastrophic flare-ups, particularly significant and of danger when occurring in confined spaces such as was the case with the Kings Cross fire.

	[[Category:Articles_needing_more_work]]		[[Category:Articles_needing_more_work]]

Editor at 09:24, 25 June 2025

2025-06-25T09:24:01Z

← Older revision		Revision as of 09:24, 25 June 2025
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−	The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: the ~~Coand (~~coanda) effect from fluid dynamics and the concept of flashover from teh physics of fire behaviour.	+	The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: the coanda effect from fluid dynamics and the concept of flashover from teh physics of fire behaviour.

−	The ~~Coand~~ effect refers to the tendency of a fast-moving stream of gas to curve toward and cling to nearby surfaces. As the stream moves, its static pressure drops, creating a pressure difference that pulls it toward the surface and keeps it attached. In the case of fire spread this refers to where rather than moving directly vertically in a fire gases may move toward and cling to nearby surfaces such as external walls.	+	The coanda effect refers to the tendency of a fast-moving stream of gas to curve toward and cling to nearby surfaces. As the stream moves, its static pressure drops, creating a pressure difference that pulls it toward the surface and keeps it attached. In the case of fire spread this refers to where rather than moving directly vertically in a fire gases may move toward and cling to nearby surfaces such as external walls.

	Flashover is a sudden, intense ignition of all combustible materials in a space. It occurs when surfaces become so hot that they release flammable gases, which spontaneously ignite once they reach a critical temperature. Prior to flashover, these gases may be present but remain too cool to ignite.		Flashover is a sudden, intense ignition of all combustible materials in a space. It occurs when surfaces become so hot that they release flammable gases, which spontaneously ignite once they reach a critical temperature. Prior to flashover, these gases may be present but remain too cool to ignite.

−	As an example of the trench effect, impacted by the ~~Coand~~ effect could be a fire burning next to a steep slope causes the flames to follow the surface—an example of the ~~Coand~~ effect in action. As the flames heat the material further upslope, it begins to emit flammable gases that eventually ignite in a flashover. The new flames, in turn, follow the slope, feeding a jet of fire that continues up the incline until the available fuel is exhausted.	+	As an example of the trench effect, impacted by the coanda effect could be a fire burning next to a steep slope causes the flames to follow the surface—an example of the coanda effect in action. As the flames heat the material further upslope, it begins to emit flammable gases that eventually ignite in a flashover. The new flames, in turn, follow the slope, feeding a jet of fire that continues up the incline until the available fuel is exhausted.

	[[Category:Articles_needing_more_work]]		[[Category:Articles_needing_more_work]]

Editor: Created page with "The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: ..."

2025-06-25T09:23:13Z

Created page with "The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: ..."

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The trench effect describes a set of conditions that can cause a fire to rapidly accelerate up an inclined surface. It arises from the interaction of two established principles: the Coand (coanda) effect from fluid dynamics and the concept of flashover from teh physics of fire behaviour.

The Coand effect refers to the tendency of a fast-moving stream of gas to curve toward and cling to nearby surfaces. As the stream moves, its static pressure drops, creating a pressure difference that pulls it toward the surface and keeps it attached. In the case of fire spread this refers to where rather than moving directly vertically in a fire gases may move toward and cling to nearby surfaces such as external walls.

Flashover is a sudden, intense ignition of all combustible materials in a space. It occurs when surfaces become so hot that they release flammable gases, which spontaneously ignite once they reach a critical temperature. Prior to flashover, these gases may be present but remain too cool to ignite.

As an example of the trench effect, impacted by the Coand effect could be a fire burning next to a steep slope causes the flames to follow the surface—an example of the Coand effect in action. As the flames heat the material further upslope, it begins to emit flammable gases that eventually ignite in a flashover. The new flames, in turn, follow the slope, feeding a jet of fire that continues up the incline until the available fuel is exhausted.

[[Category:Articles_needing_more_work]]