07.17 Can a common vent pipe be used for several day tanks?

NFPA requirements are that vent pipes be independent for each tank, except in special circumstances. The special circumstances are usually vapor recovery systems for gasoline underground tanks.

In some cases, the local regulators have allowed for the combining of day tank vents into a common vent header to the outside of the building.

Another basis for combining vents is to calculate the normal and emergency venting requirements of the day tank, and provide a single properly sized vent pipe to the exterior that is normally open, and fulfills the requirements of both functions.