What is the primary reason for using a dry-barrel fire hydrant?

The primary reason for using a dry-barrel fire hydrant is to keep the hydrant from freezing. In areas where temperatures can drop below freezing, a dry-barrel hydrant is designed so that the water supply is located below the frost line. When the hydrant is not in use, the water in the barrel drains out, preventing any remaining water from freezing and potentially causing damage to the hydrant. This design is critical in cold climates, as it ensures that the hydrant remains functional for emergency use even during winter months.

Each of the other options, while potentially beneficial, does not address the central purpose of a dry-barrel hydrant. For instance, increasing water flow is more dependent on the hydrant's design and the water distribution system rather than the dry-barrel feature itself. Maintenance costs might be influenced by various factors, but the freeze protection is the standout feature of dry-barrel hydrants. Enhancing visibility, while important for firefighters to locate hydrants quickly, is not a direct function of the dry-barrel design. Thus, the correct answer focuses on the primary function of preventing freezing, ensuring reliable operation in colder conditions.