The　effect　of　the　vent　burst　pressure　on　explosion　venting　of　a　rich　methane-air　mixture　was　experimentally　investigated　in　a　small　cylindrical　vessel.　The　experimental　results　show　that　Helmholtz　oscillation　of　the　internal　flame　bubble　of　the　methane-air　mixture　can　occur　in　a　vessel　with　a　vent　area　much　smaller　than　that　reported　by　previous　researchers,　and　the　period　of　Helmholtz　oscillation　decreases　slightly　when　the　vent　burst　pressure　increases.　The　maximum　overpressure　in　the　vessel　increases　approximately　linearly　with　the　increase　in　the　vent　burst　pressure;　however,　the　pressure　peaks　induced　by　Helmholtz　oscillation　always　remain　approximately　several　kilopascals.　The　external　flame　reaches　its　maximum　length　in　a　few　milliseconds　after　vent　failure　and　then　oscillates　in　accordance　with　the　pressure　oscillation　in　the　vessel.　The　maximum　length　of　the　external　flame　increases,　but　its　duration　time　decreases　with　the　increase　in　the　vent　burst　pressure.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.