Which of the following is NOT one of the four standard automatic sprinkler system types?

• A. Wet-pipe systems
• B. Dry-pipe systems
• C. Deluge systems
• D. Foam systems

Answer: (D)

Understanding automatic sprinkler system types means recognizing the common configurations used in most buildings. The standard automatic sprinkler systems are wet-pipe, where pipes are filled with water for immediate discharge; dry-pipe, with pipes filled with pressurized air or nitrogen and water held back at the riser to minimize unwanted water damage; deluge, in which all sprinkler heads are open and water is released through every head when the system is activated; and pre-action, which requires a initiating event before water enters the pipes to reduce accidental discharge. Foam systems, on the other hand, are specialized foam-water systems designed for specific hazards (like aircraft hangars or certain chemical facilities) that mix foam concentrate with water to blanket the fire. They’re not considered one of the standard automatic sprinkler system types, which is why they’re the correct choice for not belonging to the four.