Gas containment and release device for an inflator

An inflation device for inflating an inflatable cushion of an airbag module, the inflation device comprising:

• a first chamber and a second chamber, the first chamber having a first volume of inflation gas and the second chamber having a second volume of inflation gas;
• a first inflation opening for allowing the first volume of inflation gas to pass therethrough;
• a second inflation opening for allowing the second volume of inflation gas to pass into the second chamber;
• an external containment device sealing the first inflation opening, the containment device comprising:
• an outlet plate having an outlet opening;
• a burst disk disposed over the outlet opening;
• an initiator having a support member;
• a movable support comprising a wedge having an opening therethrough and a projectile releasably secured to the support member, a portion of the projectile being received in the opening in the wedge to position and secure the wedge between the support member and the burst disk, the wedge being disposed between the support member and the burst disk, the support providing support to the burst disk;
• wherein activation of the initiator causes the projectile to travel through the opening thereby allowing the wedge to be displaced and the burst disk to rupture.