07.16 Do the day tank vents need to terminate outside?

NFPA requirements are that fuel tank vents must terminate outside of buildings. Emergency vents are often mounted directly on the day tank and these are typically acceptable since they are normally closed vents.

Some local regulations may require that emergency vents terminate outside the building as well. If the day tank is a UL 142 double wall tank with a closed secondary containment, then the tank will have a secondary emergency vent. In some cases both the primary and secondary emergency vents, as well as the normal breathing vent, must be terminated outside the building. The size and number of these vent pipe can be a routing challenge within the building, so it is an issue worth addressing with the local fire authorities early in the project.