How is a tenant's common duct classified in relation to the building owner's common duct?

The classification of a tenant's common duct as a branch duct in relation to the building owner's common duct makes sense within the context of fire protection systems. In dry chemical extinguishing systems, duct types are categorized based on their function and connection within the overall system architecture.

A branch duct serves as a conduit that connects to a main duct, which in this scenario would be the building owner's common duct. The tenant's common duct is designed to distribute the extinguishing agent from the main duct to the specific areas within the tenant's space. By functioning in this manner, it relies on the main duct for the supply of the extinguishing agent while contributing to the overall system's coverage and effectiveness.

This classification ensures clarity in understanding the system's layout and helps with proper maintenance and code compliance, as each type of duct has specific requirements and configurations laid out by standards such as NFPA 17. Therefore, identifying the tenant's common duct as a branch duct accurately reflects its operational role in the fire protection strategy within a multi-tenant building.