Terminology Flashcards
Conduction
Fires spread through direct contact between materials.
Convection
Heat from a fire is trapped by a ceiling or rooftop and then spreads horizontally.
Radiation
The transfer of heat in the air due to electromagnetic waves. This heat can travel in multiple directions.
Direct burning
Heat comes into contact with a combustible material.
The four methods heat can be transferred.
Conduction - Convection - Radiation - Direct burning.
The three basic stages of combustion are…
Induction - Fire growth - Decay
Two phenomena that increase the risk of a fire
Flashover - Backdraught
Flashover
The near-simultaneous ignition of most directly exposed combustible material in an enclosed area.
Backdraught
The abrupt burning of superheated gases in a fire is caused when oxygen rapidly enters a hot, oxygen-depleted environment; for example, when a window or door to an enclosed space is opened or broken
What is the fire triangle?
Oxygen - Heat - Fuel
The three main reasons why an organisation has to maintain good fire safety standards are -
Social - Economic - Moral
What is a Primary Fire?
Has casualties - Involves a property - Attendance of at least five appliances - Involved a rescue.
What is a Secondary Fire?
Attendance of four or fewer appliances - Did not involve a rescue, casualties or property
RRFSO
Regulatory Reform (Fire Safety) Order
ILO
International Labour Organisation.
ISO
International Organisation for Standardisation.
Flash point
The lowest temperature at which there is sufficient vapourisation of a substance capable of producing a flash momentarily when an ignition source is applied.
Fire point
The temperature at which a fuel will continue to burn after ignition. (Five seconds or more).
Ignition point
The temperature at which a material has to be heated for sustained combustion to be initiated by a pilot source.
Auto ignition temperature
The lowest temperature a substance or material will ignite spontaneously without the presence of a pilot source of ignition. Also known as kindling point.
Vapour density (Mass of vapour per unit volume) or Relative vapour density (Density of vapour relative to air).
Indicates whether a flammable vapour is likely to rise in the air or, more commonly, sink and accumulate in low-lying areas.
Vapour pressure
The pressure exerted by a vapour when a liquid and a vapour are in equilibrium (such as a closed vessel). It increases with temperature and high vapour pressure at a given temperature means the liquid in extremely volatile and likely to produce a flammable vapour.
Flammable liquid
The flash point of between 23 degrees C and 60 degrees C. Around ambient temperature.
Highly flammable liquid
The flash point of less than 23 degrees C and a boiling point of 35 degrees or more.
Extremely flammable liquids
Liquids having a flash point of less than 23 degrees C and a boiling point of less than 35 degrees C. High volatility.
LFL and LEL
Lower flammable limit and lower explosive limit
UFL and UEL
Upper flammable limit and upper explosive limit
Inerting
The introduction of an inert (non-combustible) gas into a closed system (e.g. a container or a process vessel) to make a flammable atmosphere oxygen deficient and non-ignitable
Lower flammable limit
When mixed with air, the lowest gas concentration will support a self-emitting flame. Below the lower flammability limit, there is not enough fuel to support combustion
Upper flammable limit
The upper flammable limit (UFL) identifies the richest flammable mixture.
The basic conditions required for ignition to occur are
A mixture of fuel and oxygen in a concentration in the flammable range.
The input of sufficient heat energy.
The two basic categories of explosion
Detonation - Deflagration
UVCE
Unconfined Vapour Cloud Explosion
CVCE
Confined Vapour Cloud Explosion
BLEVE
Boiling Liquid Expanding Vapour Explosion
The four types of explosions
UVCE - CVCE - BLEVE - Dust explosion
What are the main factors and conditions determining the likelihood of a dust explosion? - 5
The presence of an ignition source - Combustibility or explosibility of the substance - Moisture content - Particle size - Concentration in the air.
