An inflator 10 of a vehicle occupant protection system, for example, contains an elongated housing 12 having a first end 14 and a second 16. The gas generator 10 includes a sealed pressurized gas supply or gas tank 18 in fluid communication with the first end 14 upon inflator 10 operation. A first seal 36 seals the first end 14 prior to gas generator 10 operation. A notched support member 56 is wedged within the housing 12 and fixes the first seal 36 against a sealed opening 24 of the gas tank 18, thereby preventing fluid flow during gas generator 10 inactivity. Upon gas generator 10 activation, the support member 56 is fractured by a force produced by an initiator 68 thereby releasing pressurized gas into the first end 14 and through the housing 12.