Experiments　were　conducted　in　a　6-m-long　duct　with　a　cross　section　of　300　mm　×　300　mm　to　investigate　the　effects　of　the　ignition,　obstacle,　and　side　vent　locations　on　the　vented　deflagration　of　18　vol%　hydrogen–air　mixtures.　Significant　effects　of　all　three　parameters　were　found.　For　ignitions　near　the　open　end,　explosion　venting　was　accompanied　by　continuous　pressure　oscillations.　When　the　ignition　location　was　near　the　closed　end,　dominant　pressure　peaks　appeared　at　the　exit　of　the　duct,　which　were　due　to　the　shockwave　resulting　from　flame　acceleration　induced　by　the　obstacle.　The　overall　maximum　internal　and　external　overpressures　increased　when　the　ignition　location　was　moved　from　near　the　open　end　to　the　closed　end　of　the　duct　but　did　not　vary　monotonically　with　the　location　of　the　obstacle　or　side　vent.　In　the　tests　with　different　obstacle　locations,　the　maximum　internal　pressure　occurred　near　the　open　end　when　the　obstacle　was　located　at　the　center　of　the　duct.　Compared　to　the　cases　without　a　side　vent,　the　maximum　internal　overpressure　was　effectively　reduced　when　a　side　vent　was　introduced　near　the　ignition　point　but　increased　when　the　side　vent　was　located　near　the　open　end　of　the　duct.　©　2019　Hydrogen　Energy　Publications　LLC