Fire: Factors Influencing the Level of Risk

Transcription

1 Fire: Factors Influencing the Level of Risk IOSH West of Scotland Branch 25 September 2014 James Doyle BSc CMIOSH

2 What is Fire? the light and heat and especially the flame produced by burning a process in which substances combine chemically with oxygen from the air and typically give out bright light, heat, and smoke; combustion or burning. A rapid, persistent chemical change that releases heat and light and is accompanied by flame, especially the exothermic oxidation of a combustible substance.

3 Composition of Fire Triangle of Fire

4 Square of Fire Oxygen Heat Fuel Senior Officer

5 Principles of Fire Safety (Demo) Turkey Fire Safety.avi

6 How Long Has Fire Been Around? Fire was first controlled by humans anywhere from about 230,000 years ago to 1.4 or 1.5 million years ago, depending on which evidence you accept as definitive. The first full time Fire department, in western culture, might have been in Rome some 2000 years ago. They had people who were selected to roam the city and not only sound the alarm and put out fires but enforce fire codes

7 Fire Prevention? Middle Ages Houses in medieval England were usually built of timber frames filled in with wattle and daub; the roofs were thatched and chimneys as such did not exist. Within the congested walled towns the houses were built in narrow streets with over hanging upper storeys. With houses having a central hearth and straw as the floor covering a fire spread could spread very easily. William the Conqueror required all fires to be extinguished at night. The most popular method of achieving this was to use a metal cover that was put over the fire to exclude the air. This cover was called a Couvert Feu which in use became Curfew.

8 Influencing Factors Oxygen (Air) - Availibility Heat Source; Nature/State; Proximity Conduction; Convection; Radiation; Flame impingement (Direct Contact) Fuel Availability; Quantity; Composition; State (Solid/Dust/Liquid/Gas/ Liquified Gas etc)

9 How Fire Works Flash Point Fire Point Decomposition of Fuel: Burning of Gases The dangerous thing about the chemical reactions in fire is the fact that they are self-perpetuating. The heat of the flame itself keeps the fuel at the ignition temperature, so it continues to burn as long as there is fuel and oxygen around it. The flame heats any surrounding fuel so it releases gases as well. When the flame ignites the gases, the fire spreads.

10 What is Smoke? A visible suspension of carbon or other particles in air, typically one emitted from a burning substance. So can you wet a towel and wrap it round your head to run through a Fire?

11 What gases are present in Fire? Carbon Monoxide (CO): causes asphyxiation Carbon Dioxide (CO2): increases inhalation of both oxygen and possible toxic gases and vapours produced by the fire. Hydrogen Cyanide (HCN):They exert an inhibiting action on the use of oxygen by the living cells of the body tissues.

12 Gases Cont. Hydrogen Chloride (HCL): damage the upper respiratory tract and lead to asphyxiation or death. (reacts with water to form HydroChloric Acid) Nitrogen (Di)oxide (NO(2): damage tissues in the respiratory tract by reacting with moisture to produce nitrous and nitric acids. Polyethylene; Polystyrene; Polyvinyl Chloride; Wood; Cellulose; Acrylic.

13 So are all Products of Combustion Bad San Diego.avi for You?

14 How Fire Spreads Conduction Convection Radiation Direct Burning front room fire.mpg Bradford City Stadium Fire.mp4 flashover clip.mpg Glasgow School of Art Fire, part 4.mp4

15 So how do I start my Risk Assessment? Understand the factors that create the risk. (Triangle of Fire) Look at: Availability of Fuel Composition/state/location/process (Wood beams/panelling/rough or smooth/sawdust) Investigate: Location of Fuel- proximity to heat sources Consider: Quantity of fuel Assess: Fuel Characteristics- SsoFlame, Diesel V Petrol Flammability limits-petrol - Car Engine v Container

16 Availability of Heat Sources? Naked Flames/Hot Working/Conducted Heat/Process Risks etc Electrical Fire- What is it?

17 Other Factors which impact on your Assessment? Human Behaviour Woolworths Fire Manchester 1979 During this fire 10 people died 26 people were rescued by the fire brigade 6 others were assisted from the building by the fire brigade 47 people were taken to hospital 6 firemen were injured, but none serious 90% of the second floor was seriously damaged by the fire The third, fourth and fifth floors were severely damaged by smoke The first floor was slightly damaged by fire The stock on the first floor, ground floor and basement was damaged by water.

18 The Circumstances? 500 customers and staff were inside the building when the fire broke out 12 calls were received by brigade control to this fire, none of which came from the store People were trapped on the second, third and fourth floors, women were seen at barred windows on the second floor, frantically calling for help. a number of customers mainly in the restaurant area refused to leave the store, regardless of the alarms and the pleading of staff; Reports indicate that some customers even continued to queue at an abandoned check-out. It is suggested that those in the restaurant section simply refused to leave because they had just paid for their meals/drinks, and wanted to make the most of their money

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20 People generally do not panic. There's still a myth in the public mind that people "panic" in an emergency, but in fact panic is very rare. Usually when people say they panicked, they just mean that they became fearful, not crazy or irrational. People are often altruistic. In an emergency, strangers will often help each other out even when they put themselves at greater risk by doing so, altruism is also linked to familiarity. That is, people are even more likely to act in helpful ways when they know each other. (Families will try to reunite)(summerland 1973: 50 Fatalities) Most people will try to exit through the door they entered. This is true even when emergency exit signs are well marked, During an emergency occupants don't want to use an exit they have no experience with--they don't know where it will lead. People will move through smoke when necessary. Fire-safety engineers used to believe that people would turn back when they encountered thick smoke. In reality, researchers have found that people will move through terrible smoke if they feel they must in order to survive. People are inertial creatures. People don't like to stop what they're doing, and often a fire alarm isn't enough of a cue to get them to drop their everyday tasks and exit a building. It's the accumulation of multiple cues-- fire alarm, smoke odour, urging from co-workers and such--that will finally convince them to do so.

21 Prevention Good Housekeeping Training Good Work Practices (Permit?) Mitigate Risks (Standard H&S Hierarchy)

22 Protection Compartmentation Structural Protection (smoke Reservoir/Building Materials etc) Smoke Detection Sprinklers Alarm Systems

23 Pitfalls As always; Assessor must know the business Care Home/Factory Process etc Impact of Structural changes; Roof Voids, Cupboards, Door Wedges, Self Closers. Impact of Maintenance work :Electrical Training: System, Drills, New Employees, Responsibilities AVOID COMPLACENCY

24 Useful Links Rescue/FireLaw/FireLaw/News Rescue/FireLaw/FireLaw/GeneralGuidance Publicly Available Specification (PAS 79)

25 A Little Knowledge is Dangerous! bonfire.wmv

26 Questions?