What is a clean agent?

• A. Electrically nonconducting, volatile, or gaseous fire extinguishant that does not leave a residue upon evaporation.
• B. Liquid solvent that leaves a sticky residue after evaporation.
• C. Water-based suppressant that forms a film.
• D. Foam concentrate used with air to blanket a fire.

Answer: (A)

Clean agents are extinguishing agents that do not conduct electricity, exist as a vapor or very rapidly evaporating liquid, and leave no residue after they evaporate. This combination allows them to suppress fires in electrical or sensitive equipment areas and in occupied spaces where cleanup or surface damage must be avoided, enabling a quicker return to service. They work by cooling, displacing, or interrupting chemical reactions in the flame without leaving a conductive or destructive residue.

The other options describe substances that leave residues or films (a sticky solvent, a water-based film), or that blanket with foam—none of which meet the defining trait of a clean agent: no residue after evaporation.