4.3.6.3.(1)

Intent 1:

To limit the probability that liquid or vapour will escape through the opening, which could lead to the ignition of vapour, which could lead to a fire or explosion, which could lead to harm to persons.

Intent 2:

To limit the probability of tampering or entry of foreign objects into the tank, which could lead to the ignition of vapour, which could lead to a fire or explosion, which could lead to harm to persons.

Intent 3:

To limit the probability of entry of precipitation into the tank, which could lead to the escape of liquid, which could lead to the ignition of vapour, which could lead to a fire or explosion, which could lead to harm to persons.