Liquefied Petroleum Gas – LPG – Liquid Petroleum Gas – LPG Gas – LP Gas
Liquefied petroleum gas – LPG – is the flammable hydrocarbon gases propane, butane, isobutane and mixes of the three gases used as fuel for gas heating, cooking, hot water, various commercial applications, and LPG vehicles. Also called liquid petroleum gas, it is used indoors in homes and outdoors for BBQs, camp stoves and many other applications.
What is Liquefied Petroleum Gas – LPG?
There are a number of fuel gases that fall under the liquified petroleum gas LPG label, including propane, butane (n-butane) and isobutane (i-butane), as well as mixtures of these gases.
They are also referred to as natural gas liquids or NGLs.
LP gas is colourless and odourless until an odourant is added for safety reasons.
When compressed, it takes liquid form, and when burnt it has a high energy content.
It can be conveniently stored and transported in gas bottles and tanks.
Liquified petroleum gas LPG is an excellent fuel for heating, cooking, and many other applications.
What is LPG made of?
It is made up of carbon and hydrogen atoms forming propane and butane whilst natural gas is made up of lighter methane.
The LPG flammable hydrocarbon gases are liquefied through pressurisation and commonly used as fuel. Natural gas is liquefied cryogenically.
Liquified petroleum gas LPG is stored in steel vessels ranging from small BBQ gas bottles to larger gas cylinders and tanks.
Propane and Butane are Natural Gas Liquids – NGLs
The typical constituent gases – propane and butane – are regarded as Natural Gas Liquids – NGLs.
However, not all NGLs are LPG.
Natural gas liquids, also called Condensate, include other hydrocarbons, too.
Interestingly, LNG – liquefied natural gas – is NOT a natural gas liquid.
What are Natural Gas Liquids – NGLs?
Raw natural gas, as it comes out of the ground, contains a number of gases and compounds, as well as impurities.
However, it is predominantly methane (CH4) gas, which is more commonly known as natural gas.
The raw natural gas must be processed to obtain pipeline quality clean, dry natural gas (methane), including the removal of impurities.
NGLs – Natural Gas Liquids – or condensate are the heavier hydrocarbons that remain after the methane (dry natural gas) and impurities are removed.
NGLs include isobutane, ethane, ethene, propene, isobutene, butadiene, pentane, pentene and pentanes plus, as well as propane and butane.
Natural gas liquids (NGL) range from 1% to 10% of the raw natural gas flow.
Various Names for Liquefied Petroleum Gas – LPG
Liquified petroleum gas LPG (liquid petroleum gas) when used in homes for cooking, heating and hot water it’s called LPG, LPG gas or LP gas.
When used in vehicles it is generally called Autogas.
In small portable cylinders, it is sometimes referred to as BBQ gas or camping gas.
Commercial applications tend to use the gas names.
Propane is used for fuel, refrigerant, and petrochemicals.
Butane is used as fuel, refrigerant, and as an aerosol propellant.
Isobutane is used as as an aerosol propellant, refrigerant and as an additive in gasoline.
Where Does Liquefied Petroleum Gas – LPG Come From?
Liquefied petroleum gas – LPG gases are found naturally in combination with other hydrocarbons and fossil fuels, typically crude oil and natural gas.
LPG is produced during natural gas processing, where it is stripped from the raw natural gas, and oil refining, where it is separated using heat.
When isolated, it can be liquefied through pressurisation and stored in pressure vessels commonly referred to as gas bottles, gas cylinders or gas tanks.
Elgas LPG is stored in various ways.
• Small SWAP’n’GO bottles contain LPG used for camp stoves, BBQs, and outdoor heating
• Cylinders ranging from 45kg-210kg for homes and businesses
• Large tanks used for industrial and commercial applications
Refined from Crude Oil
Crude oil is piped out of oil wells and into a gas trap, which separates the stream into crude oil products and ‘wet’ natural gas, which contains LPG, natural gas, and impurities.
The heavier crude oil sinks to the bottom of the trap and is then pumped into an oil storage tank and transported to refineries.
LPG is one of the refined products derived from crude oil distillation.
Crude oil undergoes a variety of refining processes, including the use of distillation towers (see image), catalytic cracking, crude distillation, and others.
Once refined, it is stored as a liquid in gas bottles such as the familiar 45kg gas bottles.
The dry natural gas, which is methane, is piped to towns and cities as natural gas for distribution by gas utility companies.
How is Liquid Petroleum Gas LPG used?
Liquid petroleum gas (LPG) is used for cooking, heating, hot water, Autogas, aerosol propellant, air conditioning refrigerant and various commercial applications, including boilers, dryers and ovens.
For home use it is typically supplied in 45kg gas bottles.
LPG has many additional uses for caravans, motorhomes, boats, camping and even hot air balloons.
Business, industrial and agricultural uses include processes such as kilns, ovens, steam boilers and forklifts.
Vaporisation: LPG Liquid to Gas
LPG liquid turns back into gas vapour at its boiling point, -42 °C or -44 °F, when you release some of the pressure in the gas bottle by turning on your gas appliance.
The steel walls of the gas bottle draw heat from the ambient temperature to heat the liquid LPG and even more when you are using it.
If you could see through the steel walls, it would look like boiling water (see image).
Vaporisation also makes the gas bottle feel colder than the ambient temperature and even colder when you are using the gas.
The gas vapour is held at the top of the bottle and the liquid is at the bottom.
The level of fill in the gas bottle comes into play when the LPG is being used, as it affects the rate of vaporisation.
The greater the fill, the greater the wall area in contact with the liquid, called the wetted area, and results in faster vaporisation.
As a liquefied gas and at a constant temperature, the pressure inside the cylinder will remain the same from full until the last of the liquid LPG is vapourised.
Under How Much Pressure is the LPG in Gas Cylinders?
The pressure of the LPG in gas bottles is dependent upon the temperature of the vessel.
The higher the temperature, the higher the pressure of the LPG in gas cylinders.
The pressure range for propane is from 152 kPa (24 PSIG) at 0ºC to 1794 kPa (257 PSIG) at 54ºC.
The propane exists as both liquid and vapour (gas) within the cylinder.
The term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the LPG in gas cylinders.
The pressure drops to zero at -43ºC (which is just below the boiling point for propane) and the pressure of LPG in gas bottles becomes greater at even higher temperatures.
LPG Chemical Formulas (Formulae)
There are a number of liquid petroleum gas (LPG gas) chemical formulas. Starting with the lowest carbon chemical formula, the Ethane chemical formula is C2H6.
The (propane) chemical formula is C3H8.
Butane and Isobutane both have the same chemical formula, C4H10, as isobutane is an isomer of butane.
Pentane (n-pentane) chemical formula is C5H12, but is only a gas over 36.1°C.
Heavier hydrocarbons (pentanes plus) are liquids or waxy solids.
LPG (LP Gas) is Heavier Than Air
In answer to the frequently asked question “Is LPG heavier than air”, the answer is “YES”.
For example, if the density of air is equal to 1.00, the density of propane is 1.53.
Butane is even heavier, at 2.00. Isobutane is heavier still, at 2.07.
On the other hand, natural gas – methane – is lighter than air, at about 60% of the density of air.
Eco-Friendly Clean Burning
LPG (propane gas) is an eco-friendly energy choice, as it is a low-carbon and low-Sulphur fuel.
LPG gases result in lower carbon dioxide (CO2) emissions than other energy sources, such as coal-fired electricity.
Replacing your electric hot water system with a 6-Star LPG continuous flow hot water system can reduce greenhouse gas emissions produced from your hot water use by about 75%.
LPG can help lower greenhouse emissions, as a transitional fuel, during the transition to renewable energy sources.
Make the Switch to ELGAS
If you are looking for an alternative to electricity, ELGAS LPG could be the perfect energy source for you.
Contact Elgas for LPG for home or business.
Our experts are on hand to answer any questions you have and will help you sort out the most cost-effective and energy-efficient service for your needs.