Pre-action sprinkler systems are characterized by which of the following?

• A. They release water automatically on sprinkler head activation
• B. They are only used in outdoor facilities
• C. They require a two-event sequence before water is released
• D. They do not exist in modern design

Answer: (C)

Pre-action sprinkler systems release water only after a two-step process, which is the main idea behind their design. First, an initiating event occurs—such as a detection signal or a manual release—that prepares the system by opening a valve or otherwise allowing the piping to be primed. Only after this initiating event does a second event, typically sprinkler head activation, release water into the system and discharge from the heads. This two-event requirement helps prevent accidental discharge, protecting areas where water damage would be especially costly.

That’s why the best choice describes a two-event sequence before water is released. Water flowing automatically just because a sprinkler head activates happens in wet-pipe systems, not pre-action systems. Pre-action systems aren’t limited to outdoor facilities and are still widely used in modern design where sensitive contents or high-value areas are at risk.