Which sprinkler system stores water in pipes and releases to heads when activated?

• A. Wet-pipe
• B. Deluge
• C. Pre-action
• D. Dry-pipe

Answer: (D)

Understanding how sprinkler systems store and deliver water helps identify which type matches water already in the piping and released to heads when activated. In a wet-pipe system, the piping itself is filled with water, so when a heat-responsive sprinkler head is activated, water immediately flows from the pipes to that head. The water is already in the network, providing instantaneous discharge at the time of activation. In contrast, a dry-pipe system keeps pipes charged with pressurized air or nitrogen and stores the actual water in a separate tank; water is released into the pipes only after activation. Deluge systems have piping that is typically empty of water until activation, with all heads releasing water simultaneously. Pre-action systems require a triggering event before water enters the pipes, adding a protective step before discharge. So, the description of water being stored in the piping and released to heads on activation aligns with a wet-pipe sprinkler system.