NEBOSH IGC Element 10 Cheat Sheet: Fire

10.1 Fire principles

Fire needs three things: a source of ignition (heat), fuel and oxygen.
- ('text', 'Fire needs three things: a source of ignition (heat), fuel and oxygen.')
Classification of fires depends on the fuel (different local classifications are accepted).
- ('text', 'Classification of fires depends on the fuel (different local classifications are accepted).')
A widely used system of fire classes:
- Class A: ordinary solids such as wood and paper.
- Class B: flammable liquids.
- Class C: gases.
- Class D: metals.
- A class for cooking oils and fats (Class F in some countries, K in others).
Local systems differ: for example, in some countries Class C means electrical fires, so always use the system taught in your own country.
- ('text', 'Local systems differ: for example, in some countries Class C means electrical fires, so always use the system taught in your own country.')
Heat is transmitted by:
- Convection (hot gases rising).
- Conduction (through solids).
- Radiation (heat waves).
- Direct burning (flames touching material).
Common causes of fire: electrical faults, arson, careless smoking, hot work, poor housekeeping, and heating equipment.
- ('text', 'Common causes of fire: electrical faults, arson, careless smoking, hot work, poor housekeeping, and heating equipment.')

Terms: Fire triangle

Tip: Controls work by removing one side of the triangle.

To reduce the chance of a fire starting:
- Eliminate or reduce the quantities of flammable and combustible materials used or stored
- Control ignition sources (including using suitable electrical equipment in flammable atmospheres)
- Use safe systems of work (for example permits for hot work)
- Keep a good standard of housekeeping
Flammable liquids should be stored in the smallest practical quantities, in closed containers, in a designated safe location or fire-resisting cabinet away from ignition sources, and only small amounts in workrooms.
- ('text', 'Flammable liquids should be stored in the smallest practical quantities, in closed containers, in a designated safe location or fire-resisting cabinet away from ignition sources, and only small amounts in workrooms.')
Structural measures slow the spread of fire and smoke: building materials with fire resistance (including fire doors), compartmentation (dividing a building into fire-resisting sections), and protecting openings and voids such as ducts and shafts.
- ('text', 'Structural measures slow the spread of fire and smoke: building materials with fire resistance (including fire doors), compartmentation (dividing a building into fire-resisting sections), and protecting openings and voids such as ducts and shafts.')

Tip: Compartmentation buys time for people to escape.

Detection and alarm systems: manual call points, smoke detectors, heat detectors and sounders (and in some places voice systems and links to emergency services).
- ('text', 'Detection and alarm systems: manual call points, smoke detectors, heat detectors and sounders (and in some places voice systems and links to emergency services).')
Portable fire-fighting equipment must be suitable for the fire risk, sited where people can find it (for example near exits), maintained, and used by trained people.
- ('text', 'Portable fire-fighting equipment must be suitable for the fire risk, sited where people can find it (for example near exits), maintained, and used by trained people.')
Extinguishing media:
- Water: cools; for class A fires; not for electrical or liquid fires.
- Foam: liquids and solids.
- Dry powder: liquids, gases and some metals.
- Carbon dioxide: electrical and liquid fires, leaves no residue but gives little cooling.
- Wet chemical: cooking oil and fat fires.
Each has advantages and limitations, so the choice depends on the type of fire.
- ('text', 'Each has advantages and limitations, so the choice depends on the type of fire.')
Access for fire and rescue services and vehicles must be planned and kept clear.
- ('text', 'Access for fire and rescue services and vehicles must be planned and kept clear.')

Tip: Never choose water for a flammable liquid or live electrical fire.

Means of escape: sufficient exits, with limits on the travel distance to a safe place; suitable stairs, passageways and doors; emergency lighting; clear exit and directional signs; and assembly points outside the building.
- ('text', 'Means of escape: sufficient exits, with limits on the travel distance to a safe place; suitable stairs, passageways and doors; emergency lighting; clear exit and directional signs; and assembly points outside the building.')
An emergency evacuation procedure sets out the alarm, who does what, how people reach the assembly point and how everyone is accounted for.
- ('text', 'An emergency evacuation procedure sets out the alarm, who does what, how people reach the assembly point and how everyone is accounted for.')
Drills test the procedure, and a roll call checks that everyone is accounted for.
- ('text', 'Drills test the procedure, and a roll call checks that everyone is accounted for.')
Provisions for people with disabilities, for example personal emergency evacuation plans, refuges and evacuation aids.
- ('text', 'Provisions for people with disabilities, for example personal emergency evacuation plans, refuges and evacuation aids.')

Tip: Escape routes must be kept clear, unlocked and well lit at all times.