What is LPG, CNG, LNG?



LPG or Liquefied Petroleum Gas, a by-product of refined crude oil, is a gas at room temperature and pressure, and a liquid at a pressure of 2 Bar.

In automobiles it is used as a propane and butane gas mixture whose chemical and physical characteristics provide outstanding performances in terms of power, flexibility and efficient engine operation.

It burns without leaving any engine carbon deposits that lead to premature wear and extends the service life of spark-plugs, valves and pistons while helping engine oil maintain its original properties longer. When burned, it produces less carbon and nitrogen oxides and unburned hydrocarbons than petrol or diesel oil, without generating any aromatic hydrocarbons or sulphur dioxide.

Refuelling is carried out by inserting a special nozzle into the cara€?s filler opening that differs in various countries (coupling type in Italy, bayonet in Holland, and ACME for the United States, Canada, Germany, Great Britain, Ireland, Austria and Belgium). It is possible to fill 80% of the tank. We suggest to check this filling value and to extinguish any flames and cigarettes while refuelling.

Gas flows from the tank and, running along the high-pressure piping, passes through an on-off solenoid valve, that is closed when the car is running on petrol or when turned off, and reaches the reducer-vaporiser. In the reducer-vaporiser, the L.P.G., heated by the engine water to ensure perfect gasification, changes from a gas to a liquid and thus at atmospheric pressure enters a special device that injects the gas into the engine according to demand. 


Natural gas (CH4) is the ecological fuel and one of the most abundant found in nature. In fact, because it has no impurities, sulphur, lead compounds or aromatic hydrocarbons, it generates a very limited amount of polluting exhaust emissions that are odourless and contain no particulates or combustion residues.

Thanks to its chemical composition, natural gas produces much less CO2 than other fuels. It also reduces the formation of ozone in the atmosphere and extends engine life. 

Natural gas can be pumped by attaching the special connector to the cara€?s refuelling valve. The types of connectors on the market differ in various countries. In most cases the filler valve is located in the engine compartment, but may also be mounted on the exterior of the vehicle. Normally, natural gas is used at an operating pressure of 220 bar. We suggest to extinguish any flames and cigarettes while refuelling. 

The gas flows from the tank and, running along the high-pressure piping, reaches the reducer, where its pressure is decreased as it passes through the reduction stages. The water from the engine cooling system provides the heat needed to prevent the reducer from freezing.

The gas leaves the reducer at atmospheric pressure and flows to a special device that injects the gas into the engine according to demand. 


LNG- Liquefied Natural Gas is natural gas (primarily methane, CH4) that has been converted to liquid form for ease of storage or transport. This process involves removal of certain components, such as water dust, helium, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid by cooling it to approximately −163 °C (−260 °F). 

The reduction in volume makes it much more cost-efficient to transport over long distances where pipelines do not exist. Where moving natural gas by pipelines is not possible or economical, it can be transported by specially designed cryogenic sea vessels (LNG carriers) or cryogenic road tankers. Octane value of LNG amounts to around 130. 

In comparison with diesel and unleaded petrol all alternative fuels described above are safer to our environment. Harmful substances are almost not present in liquid gases. Besides, in comparison with other kinds of fuel, the harmful exhaust fumes are significantly limited. 

----------------------Dated 30/10/2012

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