is
within a Division 1 or 2, or Zone 1 or 2, classified location
Entire pit or sump
Drainage ditches, separators, impounding basins
Outdoors
Indoors
Area up to 450 mm (18 in.) above ditch, separator, or basin; also, area up to 450 mm (18 in.) above grade within 4.5 m (15 ft) horizontally from any edge
Same classified area as pits
Tank vehicle and tank car 2 loading through open dome
Area inside of the tank
Within 900 mm (3 ft) of edge of dome, extending in all directions Area between
900 mm and 4.5 m (3 ft and
15 ft) from edge of dome, extending in all directions
Loading through bottom connections with atmospheric venting
1 0 Area inside of the tank
1 I Within 900 mm (3 ft) of point of venting to atmosphere, extending in all directions
2 2 Area between 900 mm and 4.5 m (3 ft and
15 ft) from point of venting to atmosphere, extending in all directions; also, up to 450 mm (18 in.) above grade within a horizontal radius of 3.0 m (10 ft) from point of loading connection
Office and rest rooms
If there is any opening to these rooms within the extent of an indoor classified location, the room shall be classified the same as if the wall, curb, or partition did not exist.
Loading through closed dome with atmospheric venting
Loading through closed dome with vapor control
1 Within 900 mm (3 ft) of open end of vent, extending in all directions
2 Area between 900 mm and 4.5 m (3 ft and
15 ft) from open end of vent, extending in all directions; also, within 900 mm (3 ft) of edge of dome, extending in all directions
2 Within 900 mm (3 ft) of point of connection of
both fill and vapor lines extending in all directions
Bottom loading with vapor control or any bottom Within 900 mm (3 ft) of point of connections,
unloading
Storage and repair garage for tank vehicles
Garages for other than tank vehicles
extending in all directions; also up to 450 mm (18 in.) above grade within a
horizontal radius of 3.0 m (10 ft) from point of connections

1 1 All pits or spaces below floor level

2 2 Area up to 450 mm (18 in.) above floor or

grade level for entire storage or repair
garage
Unclassified If there is any opening to these rooms within
the extent of an outdoor classified location, the entire room shall be classified the same as the area classification at the point of the opening.
Outdoor drum storage
Inside rooms or storage lockers used for the storage of Class I liquids
Unclassified
2
2
Entire room
Indoor warehousing where there is no flammable Unclassified If there is any opening to these rooms within
liquid transfer
Piers and wharves
the extent of an indoor classified location,
the room shall be classified the same as if
the wall, curb, or partition did not exist.
See Figure 515.3.
'The release of Class I liquids may generate vapors to the extent