Answer :
'Dry Powder' fire extinguishers, containing substances like graphite and sodium chloride, are specifically designed for Class D fires. Class D fires involve combustible metals such as magnesium, titanium, sodium, or potassium.
Why Class D Fires?
- Metals involved in Class D fires react violently with water and other common firefighting substances, making them dangerous to extinguish with typical methods. The dry powder in these extinguishers absorbs heat and smothers the fire without reacting with the metals.
How They Work:
- The dry powder forms a crust over the burning metal, effectively cutting off the oxygen supply and stopping the combustion process. The high thermal conductivity of graphite and the non-reactive nature of sodium chloride aid in efficiently controlling the fire.
Application:
- These extinguishers are typically used in environments where metal shavings, powders, or chips are present and are more naturally subject to a fire risk.
Therefore, the correct choice for the type of fire that 'Dry Powder' fire extinguishers are used for is Class D.
