The advantages of lpg are as follows: because of its relatively few components, it is easy to achieve the correct fuel to air mix ratio that allows the complete combustion of the product. This gives lpg its clean burning characteristics. Both propane and butane are easily liquefied and stored in pressure containers. These properties make the fuel highly portable, and hence, can be easily transported in cylinders or tanks to end-users. Lpg is a good substitute for petrol in spark ignition engines. Its clean burning properties, in a properly tuned engine, give reduced exhaust emissions, and extended lubricant and spark plug life. As a replacement for aerosol propellants and refrigerants, lpg provides alternatives to fluorocarbons which are known to cause deterioration of the earth's ozone layer. The clean burning properties and portability of lpg provide a substitute for indigenous fuels such as wood, coal, and other organic matter. This provides a solution to de-forestation and the reduction of particulate matter in the atmosphere (haze), caused by burning the indigenous fuels. Lpg is: colorless, odorless. (it's normal to odorize lpg by adding an odorant prior to supply to the user, to aid the detection of any leaks), flammable, heavier than air, approximately half the weight of water, non toxic but can cause asphyxiation, lpg expands upon release and 1 liter of liquid will form approximately 250 liters of vapor.