Flashing　spray　of　volatile　liquids　is　a　common　phenomenon　observed　in　many　industrial　applications　such　as　fuel　injection　of　engines,　accidental　release　of　flammable　and　toxic　pressure-liquefied　gases,　failure　of　a　vessel　or　pipe　in　the　form　of　a　small　hole　in　chemical　industry,　and　cryogenic　spray　cooling　in　laser　dermatology.　In　flashing　spray,　the　volatile　liquid　is　depressurized　rapidly　at　the　exit　of　a　nozzle　(or　a　hole　in　a　vessel)　and　becomes　superheated.　Such　superheated　liquid　(in　the　form　of　either　a　jet　or　droplets)　leads　to　explosive　atomization,　leading　to　fine　droplet　sizes　and　a　short　spray　distance.　This　paper　presents　an　experimental　investigation　of　flashing　spray　of　cryogen　R404a.　A　photographic　study　of　the　spray　is　first　conducted,　providing　visualization　of　spray　formation　and　showing　the　dynamic　characteristics　of　the　spray.　Then　the　R404a　short　spray　is　characterized　by　the　phase　Doppler　particle　analyzer　(PDPA).　The　PDPA　measurements　provide　the　distributions　of　the　diameter　and　velocities　of　liquid　droplets　in　the　spray.,　showing　the　dramatic　dynamic　variation　of　the　liquid　droplets　due　to　explosive　atomization　of　large　droplets　in　the　region　near　the　exit　of　nozzle.　The　data　finds　that　the　average　droplet　axial　velocity　increases　first　to　a　maximum,　followed　by　a　gradual　decrease,　a　typical　variation　expected　for　flashing　spray.　During　the　same　time　period,　the　average　droplet　diameter　shows　a　quick　decrease,　from　early　large　droplets　of　about　30　microns　in　diameter　to　fine　droplet　with　about　10　microns　within　about　40　mm　spray　distance.　This　study　provides　quantitative　data　on　droplet　velocity　and　diameter　in　flashing　spray,　useful　for　model　validation.　The　qualitative　results　help　to　have　a　better　understanding　of　the　flashing　spray　atomization　mechanisms　for　volatile　cryogens.　Copyright　©　2011　by　ASME.