What is a key characteristic of dry pipe systems compared to wet pipe systems?

A key characteristic of dry pipe systems is that they contain pressurized air or gas within the pipes. Unlike wet pipe systems, which have water already present in the pipes at all times, dry pipe systems keep the pipes filled with air or nitrogen. This configuration prevents water from freezing in the pipes, making dry pipe systems suitable for environments where temperatures may drop below freezing.

When a dry pipe system is activated, the pressurized air is released, allowing the valve to open and water to flow into the piping system from a remote supply. This process causes a delay in water discharge compared to wet pipe systems, where water is immediately available.

This characteristic of dry systems being filled with air makes them a preferred choice in specific applications, particularly in unheated buildings or areas prone to freezing, ensuring safety and effectiveness in fire protection.