A system and a method for delivering and metering a fixed volume of liquid, such as a liquid sterilant from a container into a vaporization system. The method for the delivering system includes the steps of sensing a requirement for additional liquid sterilant, determining whether the liquid sterilant to be added is acceptable for use, and delivering the liquid sterilant from a container into an accumulator. The method of metering the liquid sterilant into the vaporization system includes creating a vacuum in a chamber connected to the vaporizer and delivering the liquid sterilant into a vaporizer while continually sensing the flow of the delivery. The metering system maintains a slow, controlled flow in order to achieve efficient vaporization of the liquid sterilant and to provide accurate sensing of the gas/liquid interface.
