What is a characteristic of dry pipe systems in older buildings?

A characteristic of dry pipe systems in older buildings is that they have no permanent connection to a water supply. This design is significant because dry pipe systems are typically used in environments where the potential for freezing exists, such as unheated spaces. Instead of being filled with water, these systems are filled with air or nitrogen. When a fire occurs and the temperature rises, a heat-sensitive sprinkler head opens, and the pressure in the system drops, allowing water to flow into the pipes from an external source only at that moment.

This characteristic is essential for the functionality of dry pipe systems, providing flexibility while preventing freezing and potential water damage in non-heated areas. Understanding this feature is important for recognizing how these systems are designed to operate effectively in specific environments.