Cooking gas is Liquefied Petroleum Gas, LPG in short. LPG,as the name implies, is gas in liquid form under pressure. It is filled under pressure in cylinders, stored and then transported to your house.

LPG in gaseous form is almost twice as heavy as air & half as heavy as water. Thus, when liquid LPG gets converted to a gaseous state, it expands by about 250 times & When released it always settles down on the floor level. Pure LPG is colourless and also odourless, so a special odour is added at the plant to give it a distinctive smell for easy detection in case of leakage.

What happens when you activate the pressure regulator? First pressure inside the cylinder is reduced because some gas is drawn off to the burner. Then to balance the pressure some liquid vaporizes, becoming gas.