Propane, Propane Gas & Liquid Propane Gas | Is Propane LPG
What is Propane Gas? Formula for Propane
Propane or propane gas is a flammable hydrocarbon gas that is converted into liquid propane gas through pressurisation in a propane tank and commonly used for fuel in heating, cooking, hot water and vehicles.
The formula for propane is C3H8 meaning a propane molecule has 3 carbon and 8 hydrogen atoms.
Propane or liquid propane gas is a co-product of natural gas processing and a derivative of crude oil refining.
Is Liquified Petroleum Gas the Same as Propane? Is Propane the Same as LPG – Is LP Gas Same as Propane
LPG or propane? In Australia, liquified petroleum gas (LPG) is the same as propane.
Propane is liquified petroleum gas (LPG) but not all liquified petroleum gas (LP gas) is propane.
So, regarding liquified petroleum gas vs propane, is LP gas same as propane the answer is “it depends”.
Liquified petroleum gas (LPG) also includes butane (n-butane) and isobutane (i-butane), as well as mixtures of the three LPG gases.
These gases are also referred to as natural gas liquids – NGL, as they are stripped from natural gas during processing.
What is Liquid Propane? Liquid Propane Gas
Liquid propane is propane under pressure in a propane tank, as propane liquefies under pressure.
Propane gas is stored under pressure as liquid propane (liquid propane gas) in a gas bottle or propane tank with propane.
When the pressure is released from the propane tank, the liquid propane gas turns into propane gas.
Boiling Point for Propane
Liquid propane gas turns into propane gas at -42 °C or -44 °F, which is the boiling point for propane.
Conversely, propane gas turns into liquid propane gas when it drops below -42 °C or -44 °F, the boiling point for propane.
Is LPG Propane – Is Propane Gas LPG – Propane Gas vs LP Gas
Propane is LPG but not all LPG is propane.
Propane gas is one of the gases that fits the definition of LPG – Liquefied Petroleum Gas.
Regarding propane gas vs LP gas, propane gas is the same as LP gas in Australia and the USA.
LPG or propane gas is stored as a liquid in a small propane tank or larger propane tank, compressed into liquid at relatively low pressures.
The common uses for propane gas is as fuel gas for home cooking, heating, hot water and vehicles.
Propane gas can also be used for refrigerants, aerosol propellants and petrochemical feedstock.
LPG or propane gas comes from natural gas processing and crude oil refining.
Propane Gas & Liquid Propane Gas Physical Properties
Propane Gas & Liquid Propane Gas Properties Chart
Propane Gas & Liquid Propane Gas Properties |
|
| Propane Properties | Propane |
| Propane Chemical Formula | C3H8 |
| Propane Energy Content: MJ/m3 | 95.8 |
| Propane Energy Content: MJ/kg | 49.58 |
| Propane Energy Content: MJ/L | 25.3 |
| Propane Boiling Temp: Cº | -42 |
| Propane Pressure @ 21ºC: kPa | 858.7 |
| Propane Flame Temp: Cº | 1967 |
| Propane Expansion: m3/L | 0.270 |
| Propane Gas Volume: m3/kg | 0.540 |
| Propane Relative Density: H2O | 0.51 |
| Propane Relative Density: air | 1.53 |
| Propane kg per L | 0.51 |
| Propane L per kg | 1.96 |
| Propane Specific Gravity @ 25ºC | 1.55 |
| Propane Density @ 15ºC: kg/m3 | 1.899 |
Note: Some propane gas and liquid propane gas numbers have been rounded.
Where Does Liquid Propane Gas Come From?
Liquid propane gas comes from natural gas wells and oil wells.
Liquid propane gas is a fossil fuel that does not occur in isolation. Propane is found naturally in combination with other hydrocarbons.
Liquid propane gas is a co-product of natural gas processing and crude oil refining.
Propane gas is isolated, liquefied through pressurisation into liquid propane gas and stored in pressure vessels, like a propane tank, for easy storage, shipping and distribution.
How is Propane Gas Made? Propane Tank with Propane
LPG or propane gas is made during natural gas processing and oil refining.
It is separated from the unprocessed natural gas using refrigeration.
Propane gas is extracted from heated crude oil using a distillation tower.
It is then pressurised and stored as liquid propane gas in bottles or propane tank with propane.
How is Propane Gas Made from Natural Gas?
LPG or propane gas isn’t so much made from natural gas as it is separated from natural gas.
Propane gas is separated from the raw natural gas stream by ‘stripper plants’ that literally strip the propane gas from the raw natural gas stream.
It is important to understand that “raw natural gas”, as it leaves the gas well, contains other gases (including propane gas) and impurities that need to be processed out to obtain the nearly pure methane gas that we refer to as “refined natural gas” or just “natural gas”.
Applications for Propane Gas
The hospitality industry – hotels, restaurants, pubs and clubs – use propane gas for heating, cooking and hot water.- Liquid propane gas is used in a propane tank with propane for forklifts.
- Chicken farmers use propane gas to keep the chicks warm.
- Farm uses include mounting a propane tank with propane on a tractor for flame weeding.
- Stationary propane tanks fuel crop drying and irrigation pumps.
- Auto body repair shops use propane gas for the oven to cure painted cars.
- Refrigeration manufacturers use propane gas for a refrigerant gas.
- Many companies use propane gas to fuel boilers for a multitude of purposes. And the list for uses just goes on and on.
Common Uses of LPG – Propane Gas
LPG – propane gas is used in propane tanks as fuel in homes, business, industrial and agricultural, primarily for propane gas space heating, water heating and cooking.
Liquid propane gas is also used as fuel for internal combustion engine applications including cars, forklifts, buses, irrigation pumps, and fleet vehicles with propane tanks.
LPG – propane gas uses in everyday home life including a propane tank with propane for home heating, cooking, hot water heaters, gas fireplaces and clothes drying.
Outdoor home uses include a propane tank with propane for patio heaters, pool heaters, backup generators, and as BBQ fuel.
In addition, propane gas is used for propellant, refrigerant gas and petrochemical feedstock applications.
Propane gas does get used in leisure time activities including a propane tank with propane for caravans, boats, recreational vehicles, hot air balloons and camping.
LPG – propane gas is also used for fuel for many commercial and agricultural heat applications, including propane gas steam boilers, kilns, ovens and forklifts
Crop and produce drying, heating greenhouses, propane gas hot water for dairies, irrigation pumps and heating animal enclosures are just some of the agricultural applications for propane gas.
There are also many, many more propane gas applications, including propane gas power generation and the hospitality industry.
Propane Gas Used as a Fuel Gas
LPG – propane gas is used as a fuel because of its portability, in propane tanks, and high energy density.
In addition, propane gas only requires modest pressure for liquefication keeping the propane tank weight down.
LPG or Propane? Goes by Many Names
Is it LPG or propane?
In Australia, propane gas has many names.
It is also called LPG, LPG Gas, LP Gas, BBQ Gas or Autogas.
In the USA it is just called Propane.
In the UK, it is referred to as either LPG or propane.
Propane Tanks: How a Propane Tank with Propane Works – Vaporisation
A propane tank with propane is liquid propane gas stored under pressure, as a liquid, in propane tanks.
Liquid propane gas turns back into gas vapour when you release some of the pressure in the propane tank by turning on your appliance through a process called vaporisation.
To boil, the liquid propane gas draws heat from the steel walls of the propane tank which, in turn, get heat from the ambient air.
Almost all of the uses for propane gas involve the use of the gas vapour, not the liquid propane gas.
Formula for Propane – Propane Gas Composition & Structure
The formula for propane is C3H8. (Propane molecule structure model shown)
The formula for propane describes a hydrocarbon gas with 3 carbon and 8 hydrogen atoms in a propane molecule.
Propane gas is not made or manufactured, it is found naturally in combination with other hydrocarbons.
It is produced or “made” during natural gas processing and crude oil refining and stored in propane tanks.
Both processes begin by drilling oil wells.
Propane gas does not occur naturally in isolation.
LPG or Propane Gas Heating Systems for Homes
LPG or propane gas heating systems for home are an energy efficient way to keep warm and cozy.
Propane gas heating systems works well for large home spaces.
A propane tank with propane is used for storage.
LPG or propane gas heating systems are synonymous with fast home heating and real warmth.
Propane gas heating system sub-types include radiant, convectors, radiant-convectors, flued radiant, freestanding fireplaces, fireplace inserts, inbuilt fireplace gas heaters and power flued gas heaters for the home.
With a wide range of propane gas heating appliances systems to choose from, there is a model that is just right for your home.
Propane Tank with Propane
An LPG or propane tank with propane gas is typically a steel vessel for storing the gas.
Homes and small businesses typically use either 45kg gas bottles or the larger 90kg or 210kg propane tank with propane.
A BBQ propane tank with propane gas comes in 9kg and 4kg propane tank sizes.
High volume commercial users have the larger propane tank sizes, with some as large as 100 tonne capacity. A propane tank contains liquid propane gas and propane gas, as propane liquefies under relatively low pressure.
A propane tank is considered low pressure versus high pressure cylinders, as used with CNG.
Propane tank sizes and volumes vary, based on application and demand.
A small propane tank or gas bottle is portable, as used in camping.
You Can Bury a Propane Tank
You can bury a propane tank with propane gas as long as it was made for burying.
A buried liquid propane tank needs anti-corrosive coatings and cathode protection.
Underground propane tanks are tanker filled by hose.
The burying of a liquid propane tank should be handled by an experienced professional company and minimum and maximum distances from your home or business apply.
The buried propane tank must also be safely away from any ignition source.
LPG or Propane Tank Installation Distance Requirements & Regulations
Residential LPG or propane tank regulations and propane tank distance requirements are important for a safe installation.
The installation distance requirements can vary based on the size of the propane tank.
The typical minimum distance is 10 feet or 3 meters for a propane tank with propane, including ignition sources and building openings in all directions.
Propane Gas Pressure Regulators
A propane gas regulator is used to control the pressure of the propane gas delivered to the appliance, from the propane tank.
Liquid propane gas pressure regulators automatically modulate high pressure propane gas down to a maximum pre-determined limit.
The pressure within a propane tank can be 800-900kPa which is regulated down to the 2.75kPa typically required.
Liquid propane gas pressure regulators are usually factory pre-set.
Is Propane Gas Explosive? Can a Propane Tank Explode?
A propane tank explosion or blast is actually quite rare.
A propane tank can be explosive but not easily or often.
Even trying to create a propane tank explosion intentionally is very challenging.
Propane gas is explosive only under the right circumstances.
The propane gas can be explosive if it is within the limits of flammability, between 2.15% and 9.6% of the total propane gas/air mixture.
For the propane gas to be explosive, it must also collect in a confined space for an explosion to occur.
Odourant is Added to Liquid Propane Gas for Safety
In its natural state, LPG or propane gas is an odourless gas.
The distinctive smell that people associate with propane gas is actually added to liquid propane gas as a safety measure.
Without the addition of an odourant, leaking propane gas could collect without being detected.
Avoid Direct Contact with Liquid Propane Gas – Cold Burns
Caution should always be used to avoid direct exposure, as liquid propane gas is cold enough to cause severe cold burns on exposed skin.
Specific Gravity of Propane Gas and Liquid Propane Gas – Density
Unlike water, 1 kilogram of liquid propane gas does NOT equal 1 litre of liquid propane gas.
Liquid propane gas density or specific gravity is about half that of water, at 0.51.
1kg of liquid propane gas has a volume of 1.96L.
Conversely, 1L of liquid propane gas weighs 0.51kg.
1lb of liquid propane gas @ 60ºF has a volume of 0.24 US gallons.
Conversely, 1 US gallon of liquid propane gas @ 60ºF only weighs 4.23lbs, instead of the 8.34lbs it would weigh if it was water.
Propane Gaseous Expansion
Liquid propane gas expands to 270 times the volume when it goes from liquid propane gas to propane gas.
So, 1L of liquid propane gas equals 270L of gaseous propane.
As there are 1000L in a cubic meter (M3), 1L of liquid propane gas expands to 0.27M3.
1 US gallon of liquid propane gas equals 36.38ft3 of gaseous propane
Energy Content of LPG or Propane gas
LPG or liquid propane gas contains approximately 25MJ per litre.
This also converts to 6.9kWh.
More LPG or propane gas energy content facts:
1 US gallon of liquid propane gas = 91,502 BTU @ 60ºF
1ft3 propane gas = 2,488 BTU of Gas @ 60ºF
1 US gallon liquid propane gas = 1.1 therm
1 therm = 100,000 BTU
1 watt = 3.41214 BTU/h
Combustion Formula for Propane Gas
Combustion formula for propane gas in words:
Propane gas + Oxygen → Carbon Dioxide + Water + Heat
Combustion formula for propane gas expressed with molecular formulas:
(C3H8 + 5 O2 → 3 CO2 + 4 H2O + Heat)
In the presence of sufficient oxygen, propane gas burns to form water vapour and carbon dioxide, as well as heat.
If not enough oxygen is present for complete combustion, incomplete combustion occurs with water, carbon monoxide, and carbon dioxide being produced.
LPG or Propane Gas Flame Temperature
An LPG or propane gas flame burns at 1980ºC (3596ºF).
When it is burning properly, the propane gas flame is blue.
A yellow or red flame is usually indicative of incomplete combustion.
LPG or Propane Gas Limits of Flammability
LPG or propane gas lower and upper limits of flammability are the percentages of propane gas that must be present in an propane/air mixture.
This means that between 2.15% and 9.6% of the total propane gas/air mixture must be propane gas in order for it to be combustible.
LPG or Propane Flash Point
The flash point of LPG or propane is -104ºC (-155.2ºF).
This is the minimum temperature at which propane will burn on its own after having been ignited.
Below this temperature, propane will stop burning on its own.
However, if a source of continuous ignition is present, propane will burn below -104°C.
Dissipation of Propane Gas
Propane gas is heavier than air and will sink to and collect at the lowest point.
If propane gas is vented to the outside air, it will quickly dissipate with the slightest movement of air.
Conversely, if propane gas is vented into a sealed structure, with no air movement, the propane gas will collect on the floor and rise vertically as more propane gas is vented into the structure.
Propane Gas Vapour vs. Liquid Propane Gas Use
Propane can be supplied in either liquid propane gas or propane gas vapour.
The difference is in the extraction from propane tank or vessel in which it is supplied.
Most propane gas applications use vapour.
Appliances such as water heaters, room heaters and cookers all use propane gas vapour.
If these appliances were to have liquid propane gas flow to their burners, the result could possibly be a fire or similar safety hazard.
This is why a propane tank with propane should always be kept upright, so that only propane gas vapour is released.
A special liquid withdrawal propane tank with propane is used for the special applications, where required.
Eric Hahn has over a decade of experience in the LPG industry and has become a key figure in shaping how LPG is marketed and communicated. As the creator of one of the world’s first LPG blogs, Eric has authored over 200 technical posts, helping educate and inform the industry and consumers.
Eric has served on multiple committees for Gas Energy Australia and the World LPG Association (WLPGA), contributing to important discussions and advancements within the global LPG sector. He has presented at WLPGA Annual Conferences, sharing his expertise as a speaker, panellist, and panel chair.
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Steve Reynolds
Technical Consultant
Steve Reynolds is a leading expert in the LPG industry with over 22 years of experience. As part of the national management team at ELGAS, Steve ensures the safe and efficient storage, handling, and transportation of LPG. He serves as the lead investigator for incidents and collaborates with authorities on industry developments.
Steve is a technical advisor to Standards Australia and Gas Energy Australia (GEA), and an active member of the World LPG Association (WLPGA), contributing to global standards and technical reviews. He holds a BSc. (Hons) in Industrial Chemistry from UNSW and has held senior safety and technical roles at ELGAS, making him a trusted authority in LPG safety and standards.