The use of unitary liquid fuel storage chambers provides advantages in the manufacturing and assembly of inflators for use in airbag passive restraint systems. A unique process of injecting liquid fuel through a conduit which is controlled to discharge the liquid fuel beneath the rising surface of the liquid fuel in the container and then sealing the storage chamber with a unique stopper provides consistently accurately filled unitary fuel containing storage chambers. The filled and sealed unitary storage chambers can then be either stored or assembled into an inflator. The assembly of the inflator can be at a location separate from that at which the storage container is loaded with fuel, whereby the relatively hazardous loading and handling of liquid fuels can be separated from the inflator assembly area.