Dry Pipe System protects piping in areas where the ambient temperature may fall below freezing.

• A. Dry Pipe System
• B. Wet Pipe System
• C. Antifreeze System
• D. Preaction System

Answer: (A)

In areas that can get freezing temperatures, the goal is to keep water out of the pipes until needed. A dry pipe system does this by keeping the sprinkler piping filled with pressurized air (or nitrogen) and holding the water back behind a dry pipe valve. When a sprinkler head is released, air escapes, the valve opens, and water quickly fills the piping. Since most of the piping remains air-filled, there's little or no water in the lines to freeze, reducing the risk of freeze-related damage in unheated spaces.

Wet pipe systems, by contrast, have water-filled pipes all the time, which can freeze and cause damage in cold areas. Antifreeze systems introduce a antifreeze solution to prevent freezing but require careful material compatibility and maintenance. Preaction systems delay water entry for other protection goals and aren’t specifically aimed at preventing freezing in unheated spaces.