What standard must be followed for aboveground private fire service mains to protect against freezing?

The correct answer pertains to NFPA 13, which governs the installation of sprinkler systems, including considerations for fire protection systems in various environments. When it comes to protecting aboveground private fire service mains against freezing, NFPA 13 outlines requirements that help ensure the integrity and functionality of fire protection systems in cold climates.

NFPA 13 specifically addresses issues such as pipe insulation, the appropriate materials to use, and design considerations for preventing freezing conditions. This is critical because any freezing in the fire service mains could lead to blockages or ruptures, impairing the system's ability to function effectively during a fire emergency.

While other standards like NFPA 14, NFPA 20, and NFPA 22 focus on different aspects of fire protection—such as standpipe systems, pumps, and water tanks—the protection against freezing in aboveground mains is explicitly covered under NFPA 13. Therefore, this standard is the most relevant when considering how to ensure that private fire service mains operate effectively in potentially freezing conditions.