The invention provides an instrument (700) for generation of volatilized material, the instrument comprising at least one flow passage (723) having an outlet (725)； a liquid supply (733) operable to supply liquid material to the flow passage； at least one heater (705) adapted to heat the flow passage to a temperature sufficient to volatilize material in liquid form in the flow passage such that the volatilized material expands out of the outlet of the flow passage, the volatilized material optionally being admixed with air to form an aerosol； a first flow path (760b) in fluid communication with the outlet of the flow passage； a second flow path (760c) in fluid communication with the outlet of the flow passage, the second flow path being different from the first flow path； a first valve (742) in fluid communication with the outlet of the flow passage； and a controller (750) operable to control operation of the first valve such that the volatilized material or aerosol (i) flows through the first flow path when the heater is in a non-conforming condition and (ii) flows through the second flow path when the heater is in a conforming condition. The instrument may optionally comprise a mouthpiece (770) and a pressure sensor (745), and may further comprise a second valve (743) in fluid communication with the mouthpiece. Volatilized material can be supplied from a source of material by a pump (744) or another suitable mechanism. Further provided is a method of operating said instrument.
