Organic heat transfer fluids (HTFs) are widely used because of their low vapor pressures and wide ranges of working temperatures. It is a common misconception that operations involving HTFs below their flash point temperatures do not represent a hazard, but aerosols of combustible liquids at temperatures below their flashpoints have been recognized for their potential to cause fires and explosions. The hazard is further exacerbated by the paucity of experimental information about the formation and behavior of aerosols from HTF releases. This article presents droplet sizes, spray development, and aerosol formation distances for an alkylated aromatic HTF aerosol generated mechanically by means of a leak from a pressurized container into ambient air as functions of HTF temperature, pressure, and orifice size. A Malvern Laser Diffraction Particle Analyzer was used to measure aerosol droplet sizes along the centerline of the liquid sprays, and high-speed photography was used for spray visualization and interpretation of stream atomization. Effects of pressure, temperature, and orifice diameter confirm critical Weber Number theory.