What must permanently identify each subslab soil exhaust duct within the floor level?

Each subslab soil exhaust duct within the floor level must be permanently identified using a tag or stencil. This requirement ensures that the ducts are easily recognizable and can be distinguished from other ducts or systems within the building. Proper identification is crucial in facilitating maintenance, inspections, and any potential future modifications of the duct system.

The use of tags or stencils provides a clear and durable form of identification that remains in place over time, allowing for consistent recognition regardless of who is working in the building. This practice is vital for safety and compliance with mechanical codes, as it helps professionals understand the specific function of that duct and ensures that it is not confused with other systems, thereby promoting efficient operation and upkeep of the mechanical systems in place.

Options that suggest a color code, documentation, or a laboratory seal do not directly relate to the permanent identification that aids in operational safety and maintenance efficiency in the same way that tags or stencils do. While those methods might provide helpful information, they lack the immediate visibility and permanence that tags or stencils offer on site.