LIQUEFIED GASES

Petroleum gases can be liquefied by slightly compressing them. When these gases liquefy, they contract and occupy less space. They can then be transported more easily in liquid form in pressurised containers. If the pressure is released by opening the valve, the liquid from the container begins to evaporate and provides a continuous supply of gas.

There are only two families of petroleum gases which can be liquefied by compression at atmospheric pressure. These are as follows:

1. Propanes (C₃H₈) and Propylenes (C₃H₆)
2. Butanes (C₄H₁₀) and Butylenes (C₄H₈)

Propane and butane are paraffin hydrocarbons and have the general formula as C_nH_2n + 2. Methane (CH₄) and ethane (C₂H₆) must be chilled before they can be liquefied.

Another series of hydrocarbons associated with the aforementioned paraffin is called Olefins and have the general formula as C_nH_2n. These include ethylene, propylene, butylene, etc.