Tank containers must be at least 80% full, to prevent dangerous surging of the liquids in transit. On the other hand, they must not as a rule be over 95% full, or there will not be sufficient ullage space for thermal expansion. The extent of thermal expansion may be calculated for each cargo on the basis of the following formula:
D V = Va * g + D t
D V
:
change in volume
Va
:
volume at initial temperature a
g
:
coefficient of cubic (thermal) expansion
D t
:
temperature difference in degrees Celsius
Tank containers intended for transporting foodstuffs must be labeled "Potable Liquids only".
Some hazardous materials must be transported in tank containers with no in- or outlet openings below the surface of the liquid.
Tank containers are generally designed for an operating pressure of up to 3 bar (above atmospheric). The test pressure used is 4.5 bar (above atmospheric).
If the cargo requires temperature-controlled transport, tank containers can be equipped with insulation or heating. The temperature of the cargo may be precisely controlled using temperature sensors.
