Operation thumb|left|Bunsen burner flames depend on air flow in the throat holes (on the burner side, not the needle valve for gas flow): 1. air hole closed (safety flame used for lighting or default), 2. air hole slightly open, 3. air hole half-open, 4. air hole fully open (roaring blue flame). The device in use today safely burns a continuous stream of a flammable gas such as natural gas (which is principally methane) or a liquefied petroleum gas such as propane, butane, or a mixture of both.
opeRaTion tHUMB|LEFT|buNsEn BurNer fLaMes dEpend oN air flow in the throaT holEs (ON tHe burNer siDe, not tHE neEDlE ValVe FOr GAs flow): 1. aIr hoLe Closed (saFETy fLaME uSed For lIghtInG Or dEFaUlt), 2. aIR hole SLiGhTly Open, 3. aIr HoLe haLf-open, 4. air hole fULlY opeN (rOaRIng bluE FlAMe). THE device IN uSE today sAFeLY bURns a COnTInuous strEAm of a fLAmmAblE gas SucH as naturAl gas (WHich iS prinCiPaLLy mEThane) OR A liqUefiEd pEtroleuM gas Such as prOPANe, bUtANe, or a MixTUre of BOth.