Explosion　venting　is　the　most　commonly　used　technique　to　reduce　the　hazard　from　accidental　deflagration　of　combustible　gases.　Since　less　attention　is　paid　to　the　influence　of　inertial　vent　on　vented　H2/CH4/air　deflagration,　the　effects　of　area　density　(Ws)　of　a　hinged　inertial　cover　on　the　pressure　profile　and　flame　behavior　during　H2/CH4/air　deflagration,　with　hydrogen　volume　fraction　in　fuel　(χH2)　being　0.5　and　0.8,　were　investigated　by　covering　the　vent　using　aluminum　plates　with　various　thicknesses.　The　results　show　that　the　interval　between　ignition　and　the　moment　the　flame　just　travels　through　the　vent　(tout)　is　almost　independent　of　Ws,　but　the　opening　angle　of　the　panel　at　the　time　of　tout　is　closely　related　to　Ws.　For　a　given　χH2,　the　opening　angle　at　the　time　of　tout　decreases　with　an　increase　in　Ws.　For　a　certain　Ws,　the　opening　angle　of　the　panel　is　smaller　for　χH2　=　0.8　in　comparison　with　the　tests　at　χH2　=　0.5.　In　the　test　with　higher　Ws,　the　external　fireball　becomes　more　flattened.　In　tests　at　χH2　=　0.5,　p3　induced　by　acoustic　oscillations　dominates　the　internal　overpressure,　but　p2　resulting　from　the　external　explosion　becomes　the　dominant　pressure　peak　at　χH2　=　0.8.　The　maximum　reduced　overpressure　(pred)　and　maximum　external　overpressure　(pext)　are　almost　independent　of　Ws　at　χH2　=　0.5.　However,　in　tests　at　χH2　=　0.8,　pred　and　pext　increase　sharply　with　an　increase　in　Ws　from　0　kg/m2　to　2.7　kg/m2,　but　there　is　relatively　little　variation　in　pred　and　pext　as　Ws　continues　to　increase　from　2.7　kg/m2　to　24.3　kg/m2.　Except　for　the　test　with　Ws　=　0　kg/m2,　for　a　specific　Ws,　pred　and　pext　at　χH2　=　0.8　are　always　greater　than　those　at　χH2　=　0.5.　©　2024