§ 42-11. Vent pipes.

A. 

An open steel vent pipe not less than two inches in diameter without trap and draining to the tank shall be provided for each tank. The lower end of the vent pipe shall not extend through the top of the tank more than one inch.

B. 

For all tanks located beneath the lowest story of the building, or tanks located on the lowest story of the building, the vent pipe shall be two inches in diameter, and terminate in such a location as to be readily observed in the event of an overflow from the tank during filling operations.

C. 

Vent openings shall be equipped with a weatherproof hood, and shall be of sufficient area to permit proper inflow of the liquid during the filling operation.

D. 

Vent pipes shall terminate outside of the building above the street surface not less than four feet nor more than 12 feet above the fill pipe. Such vent outlet shall not be located within three feet in any direction of a window or other opening, or an exterior stairway, or fire escape. Vent pipes shall not be placed in elevator or dumbwaiter shafts, or in enclosed courts.

E. 

If necessary, because of structural conditions, to carry the vent outlet higher than 12 feet above the fill box, and if the fill lines are connected to tank trucks by tight connections and filled by pressure, a one-inch line shall be connected to the tank parallel to the fill line and terminating in the fill box with unthreaded end.

(1) 

A check valve shall be installed in the line so as to permit excess oil in the tank to flow to the fill box and shall be so set as to prevent the passage of vapor to the street.

F. 

All vent pipes must be not less than two inches in diameter.