Definition
A white crystalline chemical compound (NaHCO₃) used as the active extinguishing agent in dry chemical fire extinguishers. When heated by a fire, it decomposes and releases carbon dioxide, which smothers the flames by displacing oxygen, and leaves a residue that helps interrupt the combustion process.
Plain English
It's the powder inside a dry chemical fire extinguisher. When it hits a fire, the heat breaks it down, releasing a gas that smothers the flames.
Context Anchor
Seen during aircraft battery servicing, spill cleanup, and discussions of dry-chemical fire extinguishers.
Derivation
From the Latin sodium (the chemical element) and bicarbonate (a compound containing one hydrogen and one carbonate group). The same substance is known in everyday life as baking soda.
Why Pilots Care
Correct identification ensures the right agent is used for non-electrical fires without leaving corrosive residue on aircraft components.
Intuition Check
Do not think of sodium bicarbonate only as a kitchen product. In aircraft maintenance, the important point is that it is a chemical powder that can neutralize acid and can be used in some fire extinguishers.
Example Sentence 1
The hand-held extinguisher in the cockpit contained sodium bicarbonate, which the pilot used to knock down a small electrical fire behind the panel.
Example Sentence 2
Sodium bicarbonate extinguishers are selected for aircraft interiors because they leave no residue that could damage electrical systems.