A vapor delivery device having a reservoir (102) for containing an amount of fluid (104). An ejector (108) receives the fluid (104), and a controller (112) fires the ejector (108) to express a given dosage of the fluid (104) through a number of nozzles (110) in the ejector (108) into an airstream at a firing frequency and for a firing duration. As the amount of the fluid (104) within the reservoir (102) decreases, the controller (112) also at least one of reduces the firing frequency of the ejector (108), increases the number of nozzles (110), and increases the firing duration.
