Section 1 - Fire and Fire Protection Flashcards
a) One of the methods used to extinguish fire is smothering. Explain why this method is used
(3 marks)
b) Describe one other method to extinguish fire. (1 marks)
The fire tetrahedron is composed of the elements required to sustain a fire, they are
Oxygen
Heat
Fuel
Chemical chain reaction
Removing one of the components prevents the exothermic reaction being maintained. Smothering a fire removes oxygen from a fire causing the chain reaction, and the fire to be extinguished. Smothering is used, for example, to extinguish a chip pan fire. A fire blanket can be used to prevent oxygen reaching the burning liquid oils or fats. Cooling by water would be unsuitable in this situation.
Cooling is another method used to extinguish a fire. Water can be applied to burning paper or wood removing the heat element of the fire tetrahedron
Describe, from a scientific perspective, the following two stages of fire development:
a) Ignition (2 marks)
b) Decay (3 marks)
A
Stage one - Ignition
As identified in the fire triangle, this first stage is brought about when heat, oxygen and a fuel source
combine to achieve a chemical reaction resulting in fire, for example an electrical appliance catching
fire, or a lighted cigarette carelessly discarded in a waste paper bin. At this stage a very small fire,
generating little heat, which may well go out of its own accord, or be spotted and quickly extinguished
using for example a fire extinguisher before the next stage is reached.
Decay
Likely to be the longest stage of a fire, governed by the decrease in oxygen or fuel within the
compartment and the means of access to extinguish the fire by the fire services.
Furthermore, there is also a risk of the fire recurring where oxygen is reintroduced to such a volatile,
confined space, or where non-flaming combustibles within the compartment are ignited to start a new
fire, if not fully extinguished.
Describe the ways in which regular fire drills and alarm tests can affect behaviour in a fire. (3
marks)
Regular fire drills can affect behaviour by
1 making people familiar with the sound of the alarm
2 familiarising with escape routes and safe areas
3 Reacting quickly and calmly
4 May become complacent
Explain what is meant by passive fire protection and give two examples of different passive
fire protection systems that can be found in buildings. (4 marks)
Passive fire protection is built into the fabric of a building and does not require any energisation to function. PFP is intended to restrict a fire to its compartment of origin for a given period of time. One example of PFP is a Pipe closure collar fitted around a pipe. Another example of passive fire protection is Thin film intumescent coatings applied to structural steel. Expands into a solid char insulating the steel member and preventing the steel from reaching its critical temperature of 550C
Describe the purpose of a “Fire Action Notice” safety sign and state three instructions that you
would expect to find on a Fire Action Notice. (4 marks)
The purpose of a fire action notice is to give building occupants instructions to follow in the event of discovering a fire or hearing the alarm.
Instructions expected would be
Raise alarm
Evacuate building
Proceed to assembly point
Prohibition signs such as do not use lift or return to building unless authorised to do so
