What best describes hydro-chem/wet chemical?

• A. Dry chemical injected into a water or foam master stream
• B. Foam concentrate injected directly into the air stream
• C. Water stream used alone without additives
• D. Halogen gas extinguishing agent

Answer: (A)

Hydro-chem, or wet chemical, is described by delivering a dry chemical additive into a water- or foam-delivered master stream. The dry chemical mixes with the water (or foam) to create a wetting and soaping action that cools the fuel and, for grease/oil fires, saponifies fats to form a soapy layer that helps suppress the fire. This delivery method—using a dry chemical carried by the water/foam stream—matches how wet chemical systems are designed to operate. It isn’t simply foam injected into the air stream, or water used alone without additives, and it isn’t a halogen gas extinguishing agent.