A Bunsen burner is a type of gas burner commonly used as a heat source in laboratory experiments. The burner consists of a flat base with a straight tube extending vertically, known as the barrel or chimney. Bunsen burners are normally fitted with a hose barb at the base of the chimney to allow rubber tubing to supply the gas from a gas nozzle on the laboratory bench. There may also be a gas value on the Bunsen burner. The other critical component of a Bunsen burner is the air hole. This is located near the bottom of the chimney, just above the gas inlet. The air hole allows pre-mixing of air and gas before combustion occurs at the top of the chimney. A collar around the base of the chimney, with a hole that aligns with the air hole, acts as an air regulator, allowing the air in the pre-mixture to be adjusted.