Which option correctly describes a dry pipe sprinkler system in terms of pipe contents and climate use?

• A. Wet pipes are installed outdoors to withstand weather.
• B. Dry pipe systems have pressurized air or nitrogen in the pipes with water in the main; wet pipe systems have water-filled tubes; dry pipes are used in colder climates to prevent freezing.
• C. Dry pipes are always cheaper to maintain than wet pipes.
• D. Wet pipes are installed in every climate without exceptions.

Answer: (C)

Dry pipe sprinkler systems keep water out of the piping until a sprinkler head is activated. The pipes are pressurized with air or nitrogen, and water is held in the supply or a separate tank until needed. This arrangement prevents the water in the lines from freezing in cold climates, so these systems are used in colder environments. The option that describes dry pipes as having pressurized air in the pipes with water kept in the supply and notes their use in preventing freezing captures this essential behavior and purpose. The other descriptions either mix up how dry vs wet pipes fill or make general maintenance claims that don’t define the system’s key feature.