The invention provides a process and apparatus for delivering from a delivery port of an aerosol container having a vapor tap valve a spray of low flammability of a liquid aerosol composition containing a flammable liquefied propellant, which comprises mixing together liquid aerosol composition and gaseous propellant; subjecting the gas/liquid mixture to the constraint imposed by a flow constriction; expanding the gas/liquid mixture; subjecting the gas/liquid mixture to the constraint imposed by a second flow constriction, and again expanding the gas/liquid mixture and then passing the mixture through the remainder of the vapor tap valve to the delivery port; with each constraint and expansion increasing the gas:liquid volume ratio of the mixture and reducing the flammability of the mixture as a delivered spray.