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What is propane gas?

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

In this article:

Everything about propane - its connection to LPG, its manufacturing process, its uses, what makes it eco-friendly and more.

What is Propane Gas? What Does Propane Do – Who Uses Propane and for What Purposes

Propane is used in homes, business, industrial and agricultural, primarily for space heating, water heating and cooking. Propane is typically used in rural areas that do not have reticulated natural gas. Propane appliances include space heaters, furnaces, water heaters, cooktops, ovens, clothes dryers and pool heaters. Propane is also used as fuel for internal combustion engine applications.
Propane used as fuel for internal combustion engine applications includes cars, forklifts, buses, irrigation pumps, and fleet vehicles. Propane is called Autogas when used as vehicular fuel. New propane applications are constantly emerging as technology develops.
Propane, typically used as a fuel, is a co-product of crude oil refining and natural gas processing. Propane is categorised as one of the liquefied petroleum gases – LPG.
Propane gas, also called LPG, is available almost everywhere. What does propane do is primarily act as a fuel source. Propane does heat our homes & give us hot showers, cooking our food, power our BBQs and fuel our cars.
Propane is also used by business and agricultural for all sorts of applications.

Propane Gas

Propane gas is one of the gases that fits the definition of LPG – Liquefied Petroleum Gas.  Propane is a flammable hydrocarbon gas that is liquefied through pressurisation and commonly used for fuel in heating, cooking, hot water and vehicles. Propane can also be used for refrigerants, aerosol propellants and petrochemical feedstock.

Propane gas can be compressed into liquid at relatively low pressures. Propane is generally stored, as a liquid, in steel vessels ranging from small BBQ gas bottles to larger gas cylinders and LPG storage tanks.

Propane comes from natural gas processing and petroleum refining.

There are a number of other gases that fall under the “LPG” label, including butane (n-butane) and isobutane (i-butane), as well as mixtures of these gases and are also referred to as natural gas liquids – NGL.

Propane Physical Properties

Propane Properties Chart

Propane Properties

Properties Propane
Chemical Formula C3H8
Energy Content: MJ/m3 95.8
Energy Content: MJ/kg 49.58
Energy Content: MJ/L 25.3
Boiling Temp: Cº -42
Pressure @ 21ºC: kPa 858.7
Flame Temp: Cº 1967
Expansion: m3/L 0.270
Gas Volume: m3/kg 0.540
Relative Density: H2O 0.51
Relative Density: air 1.53
kg per L 0.51
L per kg 1.96
Specific Gravity @ 25ºC 1.55
Density @ 15ºC: kg/m3 1.899

Note: Some numbers have been rounded.

Where Does Propane Come From?

Propane is an amazing transportable gas that comes in a bottle, but what exactly is propane, where does it come from and how does it work? Propane comes from natural gas wells and oil wells.

Propane is a fossil fuel that does not occur in isolation. Propane is found naturally in combination with other hydrocarbons.

Propane then comes from natural gas processing and crude oil refinery processes. It is isolated, liquefied through pressurisation and stored in pressure vessels for easy storage, shipping and distribution.

How is Propane Made?

Propane is made during natural gas processing and oil refining. It is separated from the unprocessed natural gas using refrigeration.

Propane is extracted from heated crude oil using a distillation tower.

It is then pressurisation and stored as a liquid in cylinders and tanks.

How is Propane Made from Natural Gas?

Propane isn’t so much made from natural gas as it is separated from natural gas.

It is important to understand that “raw natural gas”, as it leaves the gas well, contains other gases (including propane) 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”.

Propane is separated from the raw natural gas stream by ‘stripper plants’ that literally strip the propane from the raw natural gas stream.

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Who Uses Propane and for What Purposes

The hospitality industry – hotels, restaurants, etc – use propane for heating, cooking and hot water. A chicken farmers usea propane to keep the chicks warm. A farmer uses of propane include flame weeding, crop drying and irrigation pumps. Auto body repair shops use propane for the oven to cure painted cars. Refrigeration manufacturers use propane for a refrigerant gas. Many companies use propane to fuel boilers for a multitude of purposes. And the list for uses of propane just goes on and on.

What is Propane Used For – Common Uses of Propane

Propane uses in everyday life include home heating, cooking, hot water heaters, gas fireplaces and clothes drying. Home everyday outdoor life uses include patio heaters, pool heaters, backup generators, and as BBQ fuel. For some people, it also includes vehicle fuel, with LPG cars and vehicles. Propane gas heating systems provide instant warmth and are available in flued gas heaters and portable gas heaters.

Propane is also used for hundreds, if not thousands, of uses. In addition, propane is used for propellant, refrigerant, vehicle fuel and petrochemical feedstock applications.

The propane uses most people can name are around the home, in their cars or for their business.

Propane does get used in leisure time activities including caravans, boats, recreational vehicles, hot air balloons and camping.

Propane is also used for fuel for many commercial and agricultural heat applications, including commercial boilers.

Business and industry use propane for a multitude of processes including steam boilers, kilns, ovens and forklifts.

Crop and produce drying, heating greenhouses, hot water for dairies, irrigation pumps and heating animal enclosures are just some of the agricultural applications for propane.

Transport is also a big user of propane, either alone or mixed with butane, to power various vehicle types.

There are also many, many more propane applications, including power generation and the hospitality industry.

Why is Propane Used as a Fuel

Propane is used as a fuel because of its portability and high energy density. In addition, it only requires modest pressure for liquefication maintaining a practical vessel weight. So, propane is used as a fuel for transportation and in areas without natural gas reticulation.

7 Important Propane Facts

1. Propane is LPG but not all LPG is propane. LPG is the acronym for Liquefied Petroleum Gas.

2. Propane is a flammable hydrocarbon gas that is liquefied through pressurisation and commonly used as fuel.

3. Propane comes from natural gas processing and petroleum refining.

4. Propane is LPG but not all LPG is propane.  Propane, along with a number of gases, falls under the “LPG” label.  The other gases include butane (n-butane) and isobutane (i-butane), as well as mixtures of the three LPG gases.

5. Propane gas can be compressed into liquid at relatively low pressure.

6. Propane is frequently used for fuel in heating, cooking, hot water and vehicles.

7. Propane is generally stored, as a liquid, in steel vessels ranging from small BBQ gas bottles to larger gas cylinders and storage tanks. (45kg gas bottles shown)

Propane Goes by Many Names

In Australia, propane 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 propane or LPG.

How Does Propane Work?

Propane is stored under pressure, as a liquid, in a gas bottle.

It turns back into gas vapour when you release some of the pressure in the gas bottle by turning on your appliance.

Almost all of the uses for propane involve the use of the gas vapour, not the liquefied gas.

What is Propane Made of?  Propane Composition – Propane Structure

Propane structure is as a hydrocarbon gas with 3 carbon and 8 hydrogen atoms in a propane molecule. The chemical formula for propane is C3H8.  (Propane molecule structure model shown)

Propane is not made or manufactured, it is found naturally in combination with other hydrocarbons.

Propane is produced or “made” during natural gas processing and petroleum refining.

Both processes begin by drilling oil wells.

Propane does not occur naturally in isolation.

Propane processing involves the separation and collection of the gas from its petroleum base and other Natural Gas Liquids (NGLs).

Following its refinement, LPG is stored and distributed as a liquid under pressure until used, at which point it is utilised as either a liquid or a gas (vapour).

Propane Gas Heating Systems for Homes

Propane gas heating systems for home are an energy efficient way to keep warm and cozy. Gas heating systems works well for large home spaces so there’s no better way to provide cozy warmth to every corner of your home than with gas heating. Propane heating systems are synonymous with fast home heating and real warmth.

Propane gas heating system sub-types for sale 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.

What is a Propane Tank?

Propane tanks are typically steel vessels for storing the common LPG gases, propane or butane. Homes and small businesses typically use either 45kg gas bottles, the larger 90kg or 210kg LPG gas bottle sizes. BBQ propane tanks come in 9kg and 4kg gas bottle sizes. High volume users have the larger propane tank sizes.

Propane tanks may also be called “Propane Gas Bottles”, “LPG Bottle”, “LPG Gas Cylinders” or just “Gas Bottle”.

Propane gas tanks contain liquid and 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 gas bottle is portable, as used in camping.

Can You Bury a Propane Tank?

Yes, you can bury a propane tank as long as it was made for burying. A buried propane tank needs anti-corrosive coatings and cathode protection. Underground propane tanks are tanker filled by hose.

The burying of a 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.


Propane Tank Installation Distance Requirements – Residential Propane Tank Regulations

Residential 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, including ignition sources and building openings in all directions.

Propane Gas Pressure Regulators – What is a Propane Regulator?

A propane regulator is used to control the pressure of the propane gas delivered to the appliance, from the propane gas bottles. Propane gas pressure regulators automatically modulate high pressure gas down to a maximum pre-determined limit.

The pressure within a gas bottle can be 800-900kPa which is regulated down to the 2.75kPa typically required.

Propane gas pressure regulators for LPG bottles are usually factory pre-set to the standard 2.75kPa operating pressure for the appliances.

A propane regulator can also be referred to as a cooking gas regulator when used with cooking appliances.

Is Propane Explosive? How & Can a Propane Gas Cylinder Explode? Propane-LPG Tank Explosion

Propane cylinder or propane-LPG tank explosions do not happen with any frequency. A propane-LPG tank (gas cylinder) explosion or blast is actually quite rare. Gas cylinders can be explosive but not easily or often. Even trying to create a propane cylinder explosion intentionally is very challenging.

Propane is explosive under the right circumstances. The propane can be explosive if it is within the limits of flammability, between 2.15% and 9.6% of the total propane/air mixture. For the propane to be explosive, it must also collect in a confined space in order for an explosion to occur.

What are the Properties of Propane?

Propane Boiling Point

Water boils at 100°C, becoming a gas (steam).

In contrast, propane boils at -42°C becoming gas vapour.

Propane stays liquid because it is under pressure in a gas cylinder.

As a liquid, it looks a lot like water.

It is colourless and odourless in its natural state.

Odourant is Added for Safety

In its natural state, propane is an odourless gas.

The distinctive smell that people associate with propane is actually added to it as a safety measure.

Without the addition of an odourant, leaking gas could collect without being detected.

Avoid Direct Contact – Cold Burns

Caution should always be used to avoid direct exposure, as liquid propane is cold enough to cause severe cold burns on exposed skin.

Specific Gravity of Propane – Density

Unlike water, 1 kilogram of propane does NOT equal 1 litre of propane.

Propane density or specific gravity is about half that of water, at 0.51.

1kg of propane has a volume of 1.96L.

Conversely, 1L of propane weighs 0.51kg.

1lb of propane @ 60ºF has a volume of 0.24 US gallons.

Conversely, 1 US gallon of propane @ 60ºF only weighs 4.23lbs, instead of the 8.34lbs it would weigh if it was water.

Propane Gaseous Expansion

Propane expands to 270 times the volume when it goes from liquid to gas.

So, 1L of liquid LPG equals 270L of gaseous propane.

As there are 1000L in a cubic meter (M3), 1L of liquid propane expands to 0.27M3.

1 US gallon of liquid propane equals 36.38ftof gaseous propane

Energy Content of Propane

Propane contains approximately 25MJ per litre.

This also converts to 6.9kWh.

More propane energy content facts:

1 US gallon of propane = 91,502 BTU @ 60ºF

1ft3 propane gas = 2,488 BTU of Gas @ 60ºF

1 US gallon propane = 1.1 therm

1 therm = 100,000 BTU

1 watt = 3.41214 BTU/h

Combustion Formula

In the presence of sufficient oxygen, propane burns to form water vapour and carbon dioxide, as well as heat.

Propane + Oxygen → Carbon Dioxide + Water + Heat

(C3H8 + 5 O2 → 3 CO2 + 4 H2O + Heat)

If not enough oxygen is present for complete combustion, incomplete combustion occurs with water, carbon monoxide, and carbon dioxide being produced.

Propane Flame Temperature

An propane flame burns at 1980ºC (3596ºF).

When it is burning properly, the flame is blue.

A yellow or red flame is usually indicative of incomplete combustion.

Limits of Flammability

The lower and upper limits of flammability are the percentages of propane that must be present in an propane/air mixture.

This means that between 2.15% and 9.6% of the total propane/air mixture must be propane in order for it to be combustible.

Propane Flash Point

The flash point of 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, it will stop burning on its own.

However, if a source of continuous ignition is present, it will burn below  -104°C.


Propane gas is heavier than air and will sink to and collect at the lowest point.

If propane is vented to the outside air, it will quickly dissipate with the slightest movement of air.

Conversely, if propane is vented into a sealed structure, with no air movement, the propane gas will collect on the floor and rise vertically as more propane is vented into the structure.

Propane Vapour (Gas) Use vs. Liquid Use

Propane can be supplied in either liquid or vapour.

The difference is in the extraction from cylinder or vessel in which it is supplied.

Most propane applications use vapour.

Appliances such as water heaters, room heaters and cookers all use vapour.

If these appliances were to have liquid propane flow to their burners, the result could possibly be a fire or similar safety hazard.

This is why propane cylinders should always be kept upright, so that only vapour is released.


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