To supersede the requirement in Sentence 3.2.8.2.(1), which would otherwise require that dangerous goods classified as flammable, lighter-than-air gases be stored in a dedicated room, and allow their storage in the open in unsprinklered buildings of combustible construction, if the aggregate capacity of expanded gas per fire compartment outside of the room is limited.
This is to limit the probability that gases will accumulate in sufficient quantity to form an ignitable mixture at floor level or in low areas, which could lead to the ignition of the gases from a nearby ignition source, which could lead to harm to persons.