Dry Powder - Class D (stored pressure)
The first type of Class D dry powder fire extinguisher contains a specially blended Sodium Chloride based dry powder used to extinguish metal fires involving magnesium, sodium, potassium, sodium potassium alloys, uranium and powdered aluminum. Heat from these types of fires causes the powder to cake and form a crust excluding air and dissipating the heat from the burning metal.
The second type of Class D dry powder fire extinguisher contains a specially developed copper extinguishing agent that was developed by the US NAVY to combat fires of lithium and lithium alloys. The copper compound smothers the fire and provides an excellent heat sink for dissipating the heat of the fire. It is the only known lithium fire fighting agent which will cling to a vertical surface making it the preferred agent on three dimensional and flowing fires.