Inlet fill pipe with horizontal exit
perpendicular to a tank radial. Discharge is
approximately 4 inches (100 mm) above tank
floor and enlarged to reduce fuel velocity.
An inverted trap is placed in the line to
serve as a liquid lock to prevent entry of
fire or an explosion from outside the fill
* = Lowest point in the tank not the sump
Overfill protection with a hydraulically
operated diaphragm control valve. Tanks
connected to commercial pipelines or marine
offload systems with restrictions on shut-off
may require diversion to additional tankage.
On aboveground tanks, ensure valve closes no
later than on high-high level. For
underground tanks, comply with NFPA 30 by
automatically shutting off the flow into the
tank when the tank is no more than 95 percent
full. Comply with most stringent of local,
state, or federal regulations. For Navy and
control valve to close the valve as a backup.
Use API RP 2350 to establish the proper
overfill level setting. On gravity drop
fills, replace valve with an integral high
level shut-off valve in the drop tube. Prior
to designing automatic valve closure features,
conduct a surge analysis on pressure filled
systems. See Plate Nos. 018 and 019.
* If pressure-filled.
A lockable, welded steel overfill protection
box (15 gallon (60 L) minimum) and a manual
(omit the drain feature on aviation turbine
Vertical Aboveground Storage Tank
Horizontal Aboveground Storage Tank
Horizontal Underground Storage Tank
Aboveground Concrete-Encased Storage Tank
Vertical Underground Storage Tank