A vaporizer device and associated methodology for providing accurate sampling through substantially efficient, complete and uniform single pass vaporization of a liquid sample by avoiding liquid pre-vaporization and downtime attributable to system damage from incomplete vaporization, particularly in the distribution, transportation, and custody transfer of natural gas. The vaporizer device includes at least one input port for receiving a liquid sample, a channel for directing the liquid to a vaporizer core and a heating assembly within the vaporizer core configured to flash vaporize the liquid sample. The vaporized sample can then be passed to an outlet for sample analysis.