Differentiate between wet-pipe and dry-pipe sprinkler systems.

Differentiate between wet-pipe and dry-pipe sprinkler systems.

• A. Wet-pipe systems keep pipes filled with air, while dry-pipe systems are always filled with water.
• B. Wet-pipe systems release water into pipes when a head is activated; dry-pipe systems release water into pipes when a head is activated but are filled with air.
• C. Wet-pipe systems have water-filled pipes that discharge immediately; dry-pipe systems keep pipes filled with pressurized air or nitrogen and release water into the pipes when a head is activated.
• D. Wet-pipe uses water mist; dry-pipe uses foam.

Answer: (C)

The main distinction is whether the piping itself is normally full of water or kept dry and pressurized with air until a head is activated. In a wet-pipe system, the pipes are always filled with water, so when a sprinkler head is heated and released, water exits immediately into the head and the discharge happens right away. In a dry-pipe system, the main piping is kept dry by filling it with pressurized air or nitrogen; water is stored in a separate reservoir and only released into the dry pipes when a head is activated, letting water push into the lines to reach the sprinkler heads. That difference explains why wet-pipe provides immediate water at the head, while dry-pipe introduces a brief delay as water moves into the dry lines, and also why dry-pipe systems are favored in unheated areas to reduce the risk of freezing.

The main distinction is whether the piping itself is normally full of water or kept dry and pressurized with air until a head is activated. In a wet-pipe system, the pipes are always filled with water, so when a sprinkler head is heated and released, water exits immediately into the head and the discharge happens right away. In a dry-pipe system, the main piping is kept dry by filling it with pressurized air or nitrogen; water is stored in a separate reservoir and only released into the dry pipes when a head is activated, letting water push into the lines to reach the sprinkler heads. That difference explains why wet-pipe provides immediate water at the head, while dry-pipe introduces a brief delay as water moves into the dry lines, and also why dry-pipe systems are favored in unheated areas to reduce the risk of freezing.