LPG changes from liquid into gas by introducing the right amount of pressure, at which point it turns into gas vapour, which is then drawn off as you use it. A pressure regulator keeps the gas pressure constant as the cylinder or bulk tank empties, until there is no remaining liquid left.

LPG comes in two types – propane and butane. Propane is stored in bulk tanks or a variety of red, green or grey cylinders (sizes: Patio Gas, 11kg, 34kg and 47kg), while butane is stored only in cylinders. Butane cylinders are either yellow or blue, and come in the following sizes: 1kg, 4.5kg, 5kg and 11.34kg.

Propane performs best at low temperatures, allowing it to be stored outdoors in tank or cylinder form all year round. Butane performs best at a temperature of 10 degrees Celsius, making it more suitable for indoor use and only suitable for outdoor use during summer months.

Each type of LPG cylinder is specially made to store propane or butane in its liquid state, under moderate pressure, until it is used.