Class D fires involve combustible metals, such as magnesium, titanium, potassium and sodium as well as pyrophoric organometallic reagents such as alkyllithiums, Grignards and diethylzinc. These materials burn at high temperatures and will react violently with water, air, carbon dioxide and/or other chemicals. The specific agents used on each type of fire are chosen for their inertness with respect to the burning material.
Class D extinguishers typically require a large amount of agent (several inches) to complete encapsulate and smother the fire which is why they are only available in 30 lb capacity for handheld units. These extinguishers are designed to softly deliver the agent so it piles up in a layer rather than the typical vigorous discharge of a conventional ABC-type extinguisher. Class D agents can also be purchased in pails and applied by scoop or shovel for smaller and/or well-contained fires.
If you have more typical fire threats, go back to the By Class page to view your other class options.
Among our customers who are preparing for potential lithium ion (LiON) battery fires, please see the Technical Note listed on our Lith-X product page.