Pressure vessel inflator having a preformed opening feature

A side impact inflatable device inflator adapted to inflate a side impact inflatable airbag cushion, comprising:

• a pressure chamber formed at least in part by an elongated, generally cylindrical unitary pressure vessel wall which includes, at a selected location, at least one preformed pressure vessel opening feature whereat the unitary pressure vessel wall preferentially opens upon application of sufficient pressure thereagainst, the unitary pressure vessel wall having an open axial end, said pressure chamber containing contents including a quantity of nitrous oxide which, upon actuation, undergoes dissociation to form dissociation products including at least one gaseous dissociation product used to inflate the side impact inflatable side impact inflatable airbag cushion and
• an initiator device fixed to the open axial end of the unitary pressure vessel wall and actuatable to be in dissociation initiating relationship with at least a portion of the quantity of nitrous oxide contained within said pressure chamber and
• wherein said unitary pressure vessel wall is formed from an intermediate part comprising a bulkhead containing the at least one preformed pressure vessel opening feature, said intermediate part also comprising first and second oppositely disposed tubular extensions of respective first and second lengths extending from the bulkhead with the first and second tubular extensions each having an open end, the first tubular extension forming a pressure vessel of the apparatus with the open end of the first tubular extension adapted to receive an initiator device and the open end of the second tubular extension adapted to receive a diffuser member.