Flow characteristics of atmospheric flash spray from a hollow cone swirl atomizer is experimentally investigated. Velocity fields due to primary and secondary spray formation are optically measured and addressed in conjunction with the drop size distributions. Injectant (water) is pressurized and heated up by controllable line heating system into the thermodynamic state supersaturated in the atmosphere, and exhausted into the atmospheric air by the swirl atomizer. Three dimensional velocity field of the flash swirl spray flow is measured by a multi-plane scanning Stereo-PIV system. The spray flow field is examined in terms of injection pressure and dimensionless superheat degree. The results show that the momentum of the primary and secondary spray is increased simultaneously with increasing in the injection pressure. Formation of the secondary spray heavily depends on the dimensionless superheat degree. The secondary spray grows with the dimensionless superheat degree while the primary spray diminishes.