It is called liquefied gas because it is easily transformed into a liquid. LPG needs only low pressure or refrigeration to change it into liquid ...At 100°C, water boils and turns into a gas (steam). On the other hand, LPG boils at -42°C and transforms into gas vapor. The conversion of a liquid to a vapor (gas) is known as vaporization. Since it is under LPG pressure in a gas cylinder, LPG remains liquid.
If a gas is cooled, its particles will eventually stop moving about so fast and form a liquid. This is called condensation and occurs at the same temperature as boiling. Hence, the boiling point and condensation point of a substance are the same temperature.