What is the main difference between preaction systems and dry pipe systems?

Prepare for the First Responder Inspector Test. Utilize sample tests, detailed explanations, and interactive flashcards to boost your confidence and knowledge. Get exam-ready!

The essential distinction is how water gets into the piping. In a preaction system, water is held back and only released into the system when a detection device triggers a valve, so water enters the pipes after an alarm or sensor activation. In a dry pipe system, the pipes are charged with pressurized air (or nitrogen) and water is held back by a dry-pipe valve; when a sprinkler head is activated, the released air lowers pressure and allows water to rush into the pipes and up to the heads. This means preaction adds a detection-trigger step before water release, while dry pipe relies on releasing the air to permit water flow once a head is triggered.