Extinguishers

Question 1

Class A

Answer 1

Solid Combustible Materials
E.g paper, wood, textiles & furnishings

Question 2

Class B

Answer 2

Flammable Liquids
I.e. petrol, diesel, oil, wax, grease, spirits & oil based paints

Question 3

Class C

Answer 3

Flammable Gases
I.e. natural gases, hydrogen, camping gas, propane, butane & methane

Question 4

Class D

Answer 4

Combustible Metals
I.e. magnesium, potassium, aluminium

Question 5

Class F

Answer 5

Cooking Oils/Fats
I.e. fats and oils

Question 6

Electric

Answer 6

Electrical fires
I.e. short circuiting equipment

Question 7

Water fire extinguisher

Answer 7

Class A only

Signal red

Cools, smothers and starves fire.

•Extinguishers with a capacity over 5 litres should last 60 seconds..
- Jet of no less than 7m/spray no less than 4m
Operating pressure of approx. 10bar
- should discharge about 95% of contents

Question 8

Foam extinguishers

Answer 8

Class A, B & F
Cools and smothers
Usually 6-9ltrs
•Extinguishers with a capacity over 5 litres should last a minimum of 30 seconds
•Operating pressure of approximately 10 bar
•Should discharge 95% of contents..
- jet no less than 5m
- can be self aspirating or non aspirating

Question 9

Dry Powder

Answer 9

• CLASS A, B, C & Electrical
• Range from 1-12kg in size
  Interferes with the chain reaction
  •Should discharge 85% of contents
  •Wind and moisture will affect efficiency
  •Visibility will be reduced
  •Powders are messy in use (electrical equipment)
  •Can damage sensitive electrical equipment
• powder treated with a flow additive (anti-caking)
• different powders for different fires

Question 10

Carbon Dioxide

Answer 10

CLASS B, Electrical & F

Starves fuel of oxygen

• 56 bar stored pressure
• range from 0.9-6.8kg
• expansion ratio of 450:1
  •Specially shaped discharge horn
  •CO2 approximately -79℃ on discharge
  •Extinguisher should discharge 95% of contents
  •Noisy on discharge
  •Visibility may be impaired
  •Discharge hose and horn will become extremely cold