LPG is stored under pressure as a liquid in a gas bottle. It turns back into a gas when you release some of the pressure in the gas bottle by turning on your appliance. A regulator ensures a consistent pressure is safely delivered from the gas bottle to your appliances. The gas bottles are connected by tubing, known as “pigtails”, to a changeover valve and the changeover valve is connected to a regulator. A gas line then runs from the regulator to your appliances. The changeover valve controls which gas bottle is in use.