NEBOSH Fire Safety Management 4

Question 1

What is the 'fire tetrahedron' and how does it differ from the fire triangle?

Accepted Answer

It adds a fourth element — the chemical chain reaction — to the three elements of the fire triangle

Answer

The fire tetrahedron adds a fourth element to the fire triangle: the uninhibited chemical chain reaction. While the fire triangle explains fire initiation, the tetrahedron explains fire sustainment. Some extinguishing agents such as dry powder work by interrupting this chain reaction (chemical inhibition) rather than removing heat, fuel, or oxygen.

Question 2

Step 2 of a fire risk assessment requires identification of people at risk. Which groups need special consideration?

Accepted Answer

Persons with disabilities, lone workers, night workers, visitors, contractors, children, and people sleeping on premises

Answer

Step 2 requires identifying everyone who may be at risk, with special consideration for vulnerable groups including persons with mobility, hearing or visual impairments, lone workers, sleeping occupants, young persons, elderly persons, visitors unfamiliar with the building, contractors, and anyone in remote or high-risk areas.

Question 3

What type of fire detection device is most suitable for areas where fast-flaming fires are the primary risk?

Accepted Answer

Ionisation smoke detector

Answer

Ionisation smoke detectors contain a small radioactive source that ionises the air in a sensing chamber. Small particles from fast-flaming fires (such as burning paper or flammable liquids) disrupt the ion current, triggering the alarm. They respond more quickly to fast-flaming fires than optical detectors but are prone to false alarms from cooking fumes.

Question 4

A foam extinguisher has which colour band and is suitable for which fire classes?

Accepted Answer

Cream band, suitable for Class A and Class B fires

Answer

Foam extinguishers have a cream colour band and are suitable for Class A fires (solid combustibles such as wood, paper, textiles) and Class B fires (flammable liquids such as petrol, oil, solvents). They should not be used on electrical fires unless they are di-electrically tested, or on Class F cooking fat fires.

Question 5

What structural fire protection measure divides a building into compartments to limit fire spread?

Accepted Answer

Compartmentation using fire-resisting walls, floors, and doors

Answer

Compartmentation divides a building into fire-resistant compartments using walls, floors, ceilings, and doors with specified fire resistance ratings. Each compartment acts as a barrier to contain fire and smoke, limiting damage, protecting escape routes, and providing time for evacuation and firefighting. Breaches from cable trays or pipes must be fire-stopped.

NEBOSH IGC Practice Test

NEBOSH IGC Practice Test

NEBOSH Fire Safety Management 4