Disclosed herein is a gas generator that contains a liquid reactant that reacts to produce a gas in the presence of a catalyst. The catalyst is contained in a carrier that is buoyant in the liquid reactant. The gas generator also has at least one carrier movement restraining member adapted to selectively control the location of the carrier, and at least one compressible body containing a volume of gas. In a first configuration, when an internal pressure of the gas generator is lower than an internal pressure of the compressible body, the compressible body increases in volume, and in a second configuration when the internal pressure of the gas generator is higher than the internal pressure of the compressible body, the compressible body decreases in volume. The carrier movement restraining member restricts the carrier's movement in the first configuration.