Which of the following is a classification of sprinkler systems?

• A. Preaction
• B. Internal Supply
• C. Full Flow
• D. External Supply

Answer: (A)

Sprinkler systems are categorized by how they release water and what activates them. A preaction system is a recognized classification because it uses a two-step release: water-filled pipes stay dry until a detection or control system is triggered, then water enters the pipes and a sprinkler head releases water only when heated. This design helps prevent accidental discharge in areas where sensitive equipment or valuable materials could be damaged.

The other terms describe where the water comes from rather than how the system operates. Internal supply and external supply refer to water sources, not a type of sprinkler system, and full flow isn’t a standalone sprinkler-system classification.