To deploy an inflatable member, such as an occupant restraint safety bag in a motor vehicle, a buffer zone is pressurized by the firing of inflation initiator to release liquid propellant into the buffer zone through ruptured frangible seals in a stationary separator disk or in a movable piston for controlled ignition. The ignited liquid propellant generates a large volume of gas that is cooled and pressurize buffered prior to inflating introduction into the safety bag.