A BRIEF INTO LIQUEFIED PETROLEUM GAS (LPG)

Did you know that the first liquid petrol gas stove was manufactured in 1912, and the first LPG-powered automobile was created in 1913?

Dr. Walter Snelling, an American scientist, discovered LPG in 1912 when he found that gases could be transformed into liquids and held under low pressure. However, a difficulty arose in the natural gas distribution process in the initial periods. Gradually, facilities were built to compress natural gas and separate gases that could be turned into liquids. LPG’s first commercial goods debuted in 1912.

Like all fossil fuels, LPG is a non-renewable source of energy. It is extracted from crude oil and natural gas. The main composition of LPG are hydrocarbons containing three or four carbon atoms. The normal components of LPG thus, are propane (C3H8) and butane (C4H10). Small concentrations of other hydrocarbons may also be present. Depending on the source of the LPG and how it has been produced, components other than hydrocarbons may also be present.

LPG is a gas at atmospheric pressure and normal ambient temperatures, but it can be liquefied when moderate pressure is applied or when the temperature is sufficiently reduced. It can be easily condensed, packaged, stored and utilized, which makes it an ideal energy source for a wide range of applications.

Normally, the gas is stored in liquid form under pressure in a steel container, cylinder or tank. The pressure inside the container will depend on the type of LPG (commercial butane or commercial propane) and the outside temperature.

When you start using LPG, some of the pressure in the container is released. Some of the liquid LPG then boils to produce vapour. Heat is needed to convert the liquid to vapour (known as the latent heat of vaporization). As the liquid boils, it draws the heat energy from its surroundings. This explains why containers feel cold to touch and why, if there is a heavy off-take, water or ice may appear on the container.

When you stop using LPG, the pressure will return to the equilibrium value for the surrounding temperature. The pressure of the LPG in the container varies with the surrounding temperature. It is also much higher than is needed by the appliances that use it; it needs to be controlled to ensure a steady supply at constant pressure. This is done by a regulator, which limits the pressure to suit the appliance that is being fuelled. It is a colourless and odourless gas to which foul-smelling mercaptan is added so that leak can be easily detected.

LPG is highly inflammable and must therefore be stored away from sources of ignition and in a well-ventilated area, so that any leak can disperse safely. Another reason why care should be taken during storage is that LPG vapour is heavier than air, so any leakage will sink to the ground and accumulate in low lying areas and may be difficult to disperse.

LPG expands rapidly when its temperature rises. So whenever a container is filled, sufficient space is left to allow for such expansion. LPG will cause natural rubber and some plastics to deteriorate. This is why only hoses and other equipment specifically designed for LPG should be used.

Although LPG is non-toxic, its abuse – (like that of solvents) – is highly dangerous. One of such abuse is the practice of dipping cooking gas cylinder inside water to conserve the gas in it. But what the promoters of this practice fail to realize is that, what dipping the gas cylinder inside water does is to reduce the rate of evaporation of the liquid gas, which minimizes the volume of the gas vapor being produced and delivered to the gas burner for combustion. In a nutshell, what you achieve by dipping your gas cylinder inside water is to reduce the quantity of calories (heat) that will be produced at your gas burner and extend the duration of your cooking.

For example, a cylinder that is not placed inside water will expend 0.25kg of gas to cook jollof-rice for 30 minutes, while the same cylinder placed inside water will expend the same 0.25kg of gas to cook the same meal of delicious jollof-rice for 45-55 minutes. So in essence, you just end up prolonging your cooking time by dipping your cylinder inside water, and at the same time exposing the cylinder to corrosion.

Sources:

https://niglpgas.com/Blogdetails.aspx?BlogId=74

https://edugreen.teri.res.in/explore/n_renew/lpg.htm