In a dry-pipe system, what is the purpose of pressurized air or nitrogen in the piping before activation?

• A. To delay water release
• B. To reduce corrosion
• C. To maintain ready pressure and enable rapid water fill when a head is activated
• D. To cool the air

Answer: (C)

In a dry-pipe system, the piping is kept under pressurized air (or nitrogen) instead of water so the system is ready to go and water can reach the heads quickly. That pressurized gas maintains a ready pressure in the dry pipes, and when a sprinkler head is opened, the air is displaced as water begins to flow into the pipes. The change in pressure signals the dry-pipe valve to release water into the system, allowing a rapid fill and delivery of water to the activated head. This setup prevents water from sitting in the pipes at all times and ensures a fast response when a head is activated. The other options don’t reflect the main purpose: delaying water release isn’t the goal, reducing corrosion isn’t the primary function, and cooling the air isn’t involved.