What are "cross-mains" in the context of sprinkler systems?

Cross-mains refer to the horizontal pipes that distribute water to the branch lines within a sprinkler system. They play a crucial role in the overall design, as they are responsible for efficiently delivering water from the main supply to various branch lines that extend to individual sprinkler heads.

Understanding the function of cross-mains is essential for proper system design, as they must be adequately sized and strategically located to ensure that all areas of a protected space receive the necessary water supply during an activation incident. This design consideration helps maintain uniform coverage and pressure throughout the system, which is vital for effective fire suppression.

In contrast, vertical pipes leading to water storage do not align with the definition of cross-mains, as they are more typically referred to as risers or supply lines. Pipes connected to the main water supply are characterized as mains themselves and do not serve the specific distributing function that cross-mains provide. Meanwhile, redundant systems for safety are not directly related to the distribution of water but pertain to backup systems designed to enhance reliability and safety.