Chapter 7 Extinguisher

Question 1

NFPA 10

Answer 1

Standard for portable fire extinguishers

Question 2

Class A

Answer 2

Water, water based, dry chem or class A foam
Ordinary combustibles - wood paper plastic textiles etc

Question 3

Class B

Answer 3

Flammable and combustible liquids and gases 
Extinguish with CO2, dry chemical and class B foam

Question 4

Class C

Answer 4

Energized electrical equipment
Can’t use water or water based.
Use class C extinguishing agents

Question 5

Class D

Answer 5

Combustible metals
Mag used in wheels and transmission components and some metal box springs for beds
Bright white fires.
Don’t use water - dry powder good but dry chemical is different than dry powder (dry powder can use potassium or sodium which will react violently)

Question 6

Class K

Answer 6

Cooking oils such as vegetable or animal fats that burn at extremely high temp.
Wet chemical systems and portable fire extinguishers

Question 7

Saponification

Answer 7

Alkaline based chemicals and certain cooking oils come into contact resulting in formation of a soapy film

Question 8

Methods used to extinguish

Answer 8

Smothering
Cooling 
Chain breaking 
Saponification 
If fuels have their own oxidizing agents (magnesium) oxygen depleting methods don’t work

Question 9

Water extinguishing methods

Answer 9

Cooling

O2 depletion

Question 10

CO2 extinguishing methods

Answer 10

O2 depletion

Cooling

Question 11

Foam extinguishing methods

Answer 11

O2 depletion

Vapour suppression

Question 12

Clean agent extinguishing methods

Answer 12

Chain inhibition

Cooling

Question 13

Dry chem extinguishing methods

Answer 13

Chain inhibition

O2 depletion

Question 14

Wet chem extinguishing methods

Answer 14

O2 depletion

Vapour suppression

Question 15

Dry powder extinguishing methods

Answer 15

O2 depletion

Heat transfer cooling

Question 16

Mechanisms for extinguishers to blow their load

Answer 16

Manual pump
Stored pressure
Pressure cartridge

Question 17

Extinguishers brief overview

Answer 17

Water-mist - deionized for electric (class a, safe for class C)
Wet chemi stored - K/alk for saponification
AFFF - for class B, has air aspirating nozzle. Let it rain down or deflect onto fuel. Seals off vapours - not for C, D, K or flowing fuels. (AFFF is corrosive)
Clean agent - replace halon. Halotron is approved as replacement. Smother class A B C.
CO2 - Class B and C. Doesn’t form a film so reignition possible. Doesn’t cool. Discharged as gas so wind. Static electricity builds up when discharging.
Dry chem -