ELGAS Knowledge Hub

Home 9 Business LPG Blogs 9 Residential LPG Composition

Residential LPG Composition

18 Apr, 2024 | Business LPG Blogs, Residential LPG Blogs

In this article:

Everything you need to know about the composition of residential LPG used for cooking heating, hot water and more

What Type of Gas is Supplied and Used in Homes – What Gas is Used in Gas Bottles – Cooking Gas Contains – Cooking Gas Cylinder

The most common gas supplied and used in homes is natural gas (methane) via gas mains, although the energy content can vary from country to country. LPG, in gas bottles, is the common alternative where there are no gas mains.
CNG and even Biogas are also used in some places. The deciding factor is the local supply situation.

Type of Gas in a Cooking Gas Cylinder

LPG is the gas in a cooking gas cylinder. It is primarily used as cooking fuel.

Wobbe Index

The Wobbe Index is used to compare the combustion energy output of different fuel gases. Not all natural gas has the same Wobbe Index.

Wobbe Index of Natural Gas & LPG

Fuel gas Upper index
Lower index
Upper index
Lower index
 Methane 12,735 11,452 53.28 47.91
 Natural Gas 12,837 11,597 53.71 48.52
 Butane 22,066 20,336 92.32 85.08
 Isobutane 21,980 20,247 91.96 84.71
 Propane – LPG 20,755 19,106 86.84 79.94

The Wobbe Index compares the combustion energy output of different fuel gases in an appliance. If two fuels that have identical Wobbe Indices, then at a given pressure and settings the energy output will also be the same.


Copyright © 2019 Elgas Ltd

What Type of Gas is Used in Homes – What Kind of Gas is Used in Homes

Natural gas (methane) it the type of gas used in homes most frequently. In areas where natural gas is unavailable, LPG, CNG or Biogas are used. Natural gas is delivered via pipelines whilst LPG and CNG are delivered in cylinders or tanks. Biogas is frequently produced on-site.

Of the four types of gas used in homes, LPG (propane) has a highest energy content at 93.2MJ/mvs natural gas (methane) at 38.7MJ/m3. CNG and Biogas are also methane, although biogas typiclly has a lower percentage of methane.

What Gas is Used in Gas Bottles – Gas is Used in Gas Bottles

The gas used in gas bottles is LPG – liquefied petroleum gas – which are either propane or butane, flammable hydrocarbons used as fuel for home heating, cooking, hot water and LPG cars and vehicles.

In reference to the kind or type of gas used in homes, the gas used in gas bottles is almost always LPG.  So, kind or type of gas used in homes is either propane, butane or a mixture of the two.

The other type of gas used in homes is natural gas (mains gas) or CNG, both of which are methane.

Propanebutane and natural gas are all hydrocarbon gases.

Propane and butane fall under the broad label of “LPG”, as liquefied petroleum gases and also referred to as natural gas liquids – NGL.

CNG – Compressed Natural Gas – is methane.

CNG supply is also a possibility, but rare for practical and economic reasons.

Biogas, with methane as the primary constituent, has the same limitations.

Cooking Gas Cylinder

A cooking gas cylinder can be a 9kg, 45kg or a 14.2kg domestic cooking gas cylinder.

Cooking gas cylinder sizes are contingent upon the usage, the requisite volume of gas and the location of the gas cylinder installation.

For those who use LPG for cooking only, an Australian cooking gas cylinder is typically a single 45kg LPG gas cylinder that lasts for a year or more. 45kg gas bottle have a cylinder capacity of 88 litres.

The standard cooking gas cylinder weight in India (fuel tank weight) has a gas cylinder weight of contents of 14.2kg ± 150 grams. Domestic cooking gas cylinder weight (fuel tank weight) is about 29.5kg for a full 14.2kg cooking gas cylinder. The empty cooking gas cylinder weight is a tare weight (empty gas cylinder weight) of approximately 15.3kg.

BBQ gas bottle sizes come in 4kg & 9kg gas bottle dimensions, cylinder capacity & gas bottle sizes (propane gas bottle sizes). Small LPG gas bottles are portable, as used in camping.

LPG gas bottles include a main gas valve for controlling the release of the gas. The Pressure Relief Valve (PRV) is a safety device incorporated into the main gas valve on the LPG gas bottles. If the pressure of the gas inside the LPG gas bottle increases, as the result of a fire or other heat source, the pressure relief valve releases some of the gas to relieve the pressure.

The various gas bottles sizes and cylinder capacity contain liquid and gas, as LPG – Liquefied Petroleum Gas – liquefies under pressure. An LPG gas bottle is considered low pressure versus high pressure gas bottle sizes, as used with CNG.

Compressed natural gas storage is the storage of gaseous methane at the high pressure of 20 – 25 MPa (200 bar to 250 bar) in special CNG gas cylinders. CNG – compressed natural gas storage cylinders have a tare weight approximately 3x heavier than comparable capacity LPG cylinders.

Cooking Gas Contains

Cooking gas contains either natural gas (methane) or LPG.  If it is LPG, cooking gas contains either propane, butane or a mixture of the two. If the cooking gas is CNG or Biogas, the main constituent is still methane.

Difference between CNG and Propane-LPG – LPG Energy Content

The big difference between CNG and propane is in volumetric energy density. LPG energy content is almost 3x the energy density with 25MJ/L for LPG-propane versus only 9MJ/L for CNG.

In other words, for comparable capacity cylinders, the LPG energy content means LPG cylinders will last more than twice as long.

Another major difference between CNG and propane is that CNG storage pressures can be more than 10x that of LPG.

For example, LPG pressure is less than 2 MPa whilst CNG is 20 – 25 MPa.

This much higher pressure requires a much heavier and more expensive cylinder or tank.

It also means it is impractical to make them large enough to offset the energy density deficit.

This is due to the size and weight required.

CNG vs LPG for Gas is Used in Gas Bottles

Due to the greater LPG energy content, a CNG cylinder would need replacement more than twice as often. This means the inconvenience of checking the CNG cylinders and placing orders much more often.

The homeowner would also have to absorb extra freight costs.

This would result from the extra deliveries and added weight.

This is because high pressure CNG cylinders weigh more than twice as much.

For example, an empty 45kg LPG cylinder only weighs approximately 35kg.

An empty CNG cylinder, with comparable volume capacity, is about 108kg.

So, when comparing empty cylinders, a CNG cylinder is 3x the weight. 

This also makes it impossible to increase the cylinder size to hold an equal amount of energy.

The cylinder would be too large and too heavy to transport for exchange purposes.

Higher cylinder rental is also likely, as the heavier CNG cylinders cost more.

Finally, the equipment to fill the CNG cylinders is expensive – much more than LPG.

The supplier would need to offset these higher costs in the cost of the gas.

It is the energy density and pressure that affect the comparable convenience and affordability of use.

Kind-Type of Gas is Used in Homes in Your Country or Area

Assuming that the kind-type of gas is used in homes is LPG, it can be propane, butane or a mixture of the two. The relative availability and economics of the different kind-type of gas is used in homes drive the differences.

For example, the LPG supplied in both the USA and Australia is pure propane.

Some countries, like New Zealand, provide a propane/butane blend.

In certain countries, like England, you can just buy propane or butane.

How is Cooking Gas Produced – Gas is Used in Gas Bottles

Cooking gas is produced using the LPG gas manufacturing process that occurs during natural gas processing and oil refining, because cooking gas is used in gas bottles is LPG (propane) and not some different gas. Cooking gas can also be produced using natural gas or piped gas.

Weather and Seasonal Effects on the Gas Used in Gas Bottles

Weather, or more specifically temperature, can affect the gas is used in gas bottles. Propane works better as the gas is used in gas bottles in cold climates.

Propane will continue to vaporise – turn to gas – even in low temperatures.

Propane’s biggest advantage is a lower boiling temperature, at -42°C vs -0.4°C for butane.

Boiling Points for
Propane & Butane

LPG (1atm) Liquid Vapour (Gas)
Propane < -42°C ≥ -42°C
Butane < -0.4°C ≥ -0.4°C


So, propane will continue to vaporise at temperatures well below 0°C.

With butane, when it drops below freezing, you end up with no gas.

Some countries, like Italy, vary the mix by season.

In NZ, they even vary the mix by latitudes, as well as by season.

For example, New Zealand’s North Island and South Islands may receive different mixtures.

The colder regions get a different proportion of propane, vs butane, in winter.

Needless to say, propane is the preferred choice for cold weather climates.

The Name Game

The names for the gases are dependent upon what country you are in.

In Australia, we call it LPG but it is propane.

In New Zealand, LPG is almost always a propane and butane mix.

In the USA, they don’t use the term LPG often.  They just call it “Propane”.

In some countries, like England, you buy propane or butane by name.

In other countries, they call it “GPL” or “GLP” instead of “LPG”.

This is because the acronyms comes from different languages and syntax.

For example, in French it is “gaz de pétrole liquéfié” or in Spanish it is “gas licuado de petróleo”.

Final Thoughts

For many people, the kind or type of gas used in homes or gas used in gas bottles is indistinguishable and never pose an issue.

However, for others the various gases provide the flexibility for use in diverse conditions.

Either way, LPG is the most common gas used in gas bottles.

View More LPG Gas Blogs

New Residential LPG customer?

New Business LPG customer?

Existing ELGAS customer?