The amount of venting to relieve the pressure and of water to cool tanks of
flammable liquids exposed to fires are examined. The rise in pressure and
temperature have been assessed from estimates of the heat such a tank would
receive from a fire in its own or another bund. From the values to which the
pressure and temperature rise should be limited the amount of pressure relief
and water cooling have then been calculated. The pressure relief is close to
the values recommended by the National Fire Protection Association though the
provision of water cooling gives some grounds for reducing the sizes of vent area.
Theoretically about 1/6th of the rate recommended by the National Fire Protection
Association is capable of extracting all the heat to which the tank is exposed
but this requires all the water to be vaporized and none lost by splashing. This
would require impractically small nozzles distributed closely over the whole of
the circumferential area of the tank and in view of this it is doubtful that any
worthwhile reduction in the recommended rates could be effected without further
experimental study.
