Sentence 3.6.2.7.(8)

Intent 1:

To limit the probability that escaped liquid will spread outside the vault, which could lead to the ignition of vapour by a nearby ignition source, which could lead to harm to persons.

Intent 2:

To limit the probability that ignited liquid from a fire in the vault will spread outside the vault, which could lead to the spread of fire to other parts of the building, which could lead to harm to persons.