Stratified　vapor–air　mixtures　are　formed　owing　to　evaporation　after　a　leakage　of　gasoline　in　confined　spaces.　In　this　study,　the　effects　of　ignition　position　and　ignition　delay　(tig),　defined　as　the　time　interval　between　ignition　and　the　moment　of　fuel　spill,　on　the　ignitability　and　flame　behavior　of　the　stratified　vapor　above　a　0.8-mm-thick　gasoline　layer　were　experimentally　investigated　in　a　horizontal　duct.　Experimental　results　revealed　that　the　ignitability　of　the　stratified　gasoline　vapor　depended　on　both　ignition　position　and　tig.　The　closer　the　ignition　source　was　to　the　oil　surface,　the　earlier　the　local　stratified　gasoline　vapor　became　ignitable　and　thereafter　lost　flammability.　A　two-zone　flame　structure,　including　a　blue　premixed　flame　and　a　following　yellow　diffusion　flame,　was　observed,　and　the　blue　flame　propagated　along　only　a　certain　layer　of　the　gasoline　vapor.　The　depth　of　the　leading　blue　flame　first　increased　and　thereafter　decreased　with　an　increase　in　tig.　The　heat　release　owing　to　the　yellow　diffusion　flame　played　an　important　role　in　the　maximum　explosion　overpressure　(Pmax),　which　closely　related　to　both　ignition　position　and　tig.　For　a　certain　tig,　Pmax　was　nearly　independent　of　ignition　position.　The　relationship　between　Pmax　and　tig　varied　with　ignition　position.　The　highest　value　of　Pmax　was　obtained　when　ignition　source　was　around　the　center　of　the　duct,　and　the　lowest　value　of　66　kPa　appeared　when　ignition　source　was　close　to　the　duct　roof.　©　2021