HYDROCARBON
ENGINEERING
56
increasing terminal
efficiency, provide a
safer work
environment, and
reduce pollution.
All tank farms are
different and the risks
vary based on things
like location, products
stored, tank integrity
and operational
procedures. API 2350
categorises tanks
based on attendance
level and degree of
complexity. These
categories are a
method of grouping
all the possible tank
overfill gauging
configurations into
three broad
configuration
categories. Although
the standard says
nothing about which
category is ‘better’ it
generally understood
that, the higher the
category, the more
reliable is the gauging
and alarm system:
Category 1
Category 1 systems are
essentially manual
systems such as
measurement of the
level by insertion of a
tape or rod, which
indicates the level of
oil on it. Although an
automatic tank gauge
(ATG) may be at the
tank and used for
level measurement, it
has no capability to
transmit level signals
so all information
about level is
localised to the tank.
This category should
only be used when the
risks are low (no Class
1 liquids), the receipt
operation is
infrequent, the rate of
level rise is slow and
where the operation is
so simple that an
Figure 1.
Definition of overfill protection system categories.
Figure 2.
Automatic overfill prevention system with powerful overfill prevention
in line with API 2350.
