Airbag inflator

An airbag inflator (200, 300) for inflating an airbag has a tubular inflator housing (11) having a first end (A) and a second end (B). A gas release mechanism (80) has an exhaust port end or housing (85) at the first end (A) for releasing gas directly from the tubular inflator housing (11) to ambient air, bypassing the airbag. A heater assembly (2) containing a gas generant is located and attached at the second end (B). An igniter (3) ignites the contents of the heater assembly (2). A primary gas vent port (70) vents gas from the tubular inflator housing (11) into an airbag during normal deployment of the airbag. The gas release mechanism (80) has a passageway (84) for exhausting gas from the tubular inflator housing (11) to an exhaust port (85). A seal (82, 83) seals the passageway or opening (84) of the gas release mechanism (80). An igniter (3) opens the seal (82, 83) to terminate or slow deployment and inflation of the airbag through the primary vent port (70).