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LPG Properties & LPG Composition –  What Are the Properties of LPG

Water boils at 100°C or 212°F, becoming a gas (steam). In contrast, LPG (propane) boils at -42°C or -44°F, becoming gas vapour. LPG stays liquid because it is under pressure in a gas cylinder. Liquid density is about half that of water.

In its natural state, LPG is a colourless and odourless gas. Odourant is added for safety.

LPG Composition – Components of LPG

LPG composition is primarily propane, butane, isobutane, butylenes, propylene and mixtures of these gases, which are the components of LPG and all with different LPG properties. LPG is composed of liquid or gas (vapour), depending on pressure and LPG gas temperature.

The domestic LPG composition and the commercial LPG composition are typically the same propane, butane or a mixture of the two gases.

LPG – Liquefied Petroleum Gas – is produced during natural gas processing and petroleum refining.

Natural Gas Liquids – NGL – have the same LPG composition and gas temperatures plus a few more gases not normally included in LPG.

The full NGL list of components of LPG includes ethane, ethene, butylenes, propylene, propene, isobutene, butadiene, pentane, pentene and pentanes plus, as well as propane, butane and isobutane.

LPG Gas Constituents

Liquefied Petroleum Gas – LPG – constituents are primarily propane, butane, isobutane, butylene, propylene and mixtures of these gases. LPG gas constituents are produced from crude oil reefing and natural gas processing. They are liquid under pressure and gas at room temperature and pressure.

LPG Properties – What are the Properties of LPG – Properties of Propane and Butane

The properties of LPG (properties of propane and butane) include: LPG is liquid under pressure but becomes gaseous in ambient conditions. LPG vapour is about 1.55 (propane) to 2.08 (butane) times heavier than air. LPG boiling point is between -42°C to -0.4°C, depending on the propane to butane constituent ratio in the LPG gas mixture.

The properties of LPG (propane) are -42°C boiling point, -188°C freezing point, heavier than air density, C3H8 chemical formula, 1967ºC flame temperature, 470°C auto ignition temperature, -104°C flash point, temperature based pressure, Ethyl Mercaptan odour, 2.15% to 9.6% LPG/air limits of flammability and more.

List of LPG Properties – Properties of Propane and Butane

Properties of LPG (properties of propane and butane) include:

  • LPG is primarily propane and butane. Both gases have adiabatic flame temperature of about 1970°C, when burned in air.

  • LPG (propane) gas boiling point temperature: -42 °C or -44 °F

  • LPG (propane) gas melting/freezing temperature: -188 °C or -306.4 °F

  • Heavier than Air LPG density (Propane Density) – LPG specific gravity (Propane specific gravity)

  • LPG composition – components – constituents: Propane, Butane & Isobutane

  • LPG chemical formula – molecular formula: C3Hor C4H10

  • LPG gas flame temperature: 1967 ºC or 3573 ºF

  • LPG-Propane ignition temperature (in air): 470°C – 550°C (878°F – 1020°F)

  • LPG-Propane auto ignition temperature: 470 °C or 878 °F

  • LPG flash point: -104°C or -156°F

  • LPG vapour pressure: 637 kPa @ 27°C (128 PSIG @ 80°F)

  • LPG odour: Ethyl Mercaptan added

  • LPG appearance: clear

  • LPG energy content: 25 MJ/L or 91,547 BTU/Gal (60°F)

  • Gaseous expansion of LPG: 1 L (liquid) = 0.27 M3 (gas)

  • Combustion formula for LPG:  C3H8 + 5 O2 → 3 CO2 + 4 H2O + Heat (complete combustion)

  • LPG limits of flammability: 2.15% to 9.6% LPG/air

  • LPG properties nomenclature

  • Molecular weight of LPG components: Propane is 44.097 kg/kmole – Butane (n-butane) is 58.12 kg/kmole

All of the above are the properties of LPG.

LPG Properties Chart

LPG (Propane) Chemical Properties Chart

 LPG – Propane Boiling Point
 -42 °C  or  -44 °F
 LPG Melting – Freezing Point
 -188 °C  or  -306.4 °F
 Specific Gravity of Liquid LPG-Propane
 0.495 (25°C)
 LPG Density Propane Gaseous Density
 1.898 kg/m3 (15°C)  or  0.1162 lb/ft3
 Energy Content of LPG
 25 MJ/L or 91,547 BTU/Gal (60°F)
 LPG Gaseous Expansion
 1 L (liquid) = 0.27 M(gas)
 Propane Flame Temperature
 1967 ºC  or  3573 ºF
 Propane Ignition Temperature in Air  470°C – 550°C (878°F – 1020°F)
 Limits of Flammability
 2.15% to 9.6% LPG/air
 Propane Auto Ignition Temperature
 470 °C  or  878 °F
 Molecular Weight
 44.097 kg/kmole

  Note: Some numbers have been subject to rounding.

10 Important LPG – Propane Facts

1. LPG (or LP Gas) is the acronym for Liquefied Petroleum Gas or Liquid Petroleum Gas.

2. LPG is a group of flammable hydrocarbon gases liquefied through pressurization.

    They are, in most cases, used as fuel.

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

4. There are a number of gases that fall under the “LPG” label.

    These include propane, butane and isobutane (i-butane), as well as mixtures of these gases.

5. LPG gases are compressible into liquid at low pressures.

6. The common uses for LPG include use for fuel in heating, cooking, hot water and vehicles.

    It is also utilized for refrigerants, aerosol propellants and petrochemical feed stock.

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

8. “Wet gas” is a term that is sometimes used to describe LPG, as a result of its liquidity.

9. An alternate reference for LPG (propane) is as a Natural Gas Liquid – NGL.

10. In nature, propane does not occur alone.

LPG = Propane

Propane molecule

LPG is propane.

It is also called LPG Gas, LP Gas, Propane, BBQ Gas, Camping Gas or Autogas.

LPG can be other gases in other countries.

Odourant Added for Safety – Smell in Propane

In its natural state, LPG is an odourless gas.

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

Without the addition of a smell in propane, leaking gas could collect without detection.

Avoid Direct Contact – Cold Burns

Always use caution should to avoid direct exposure, as liquid LPG is cold enough to cause severe cold burns on exposed skin.

3 Things You Didn’t Know About LPG

While you may know some of these facts, chances are you don’t know all of them.

Have a read and learn more about:

  1. The Source of LPG

  2. LPG is a Renewable Energy Source

  3. LPG is NOT Coal Seam Gas (CSG)

The Source of LPG

Many people mistakenly think of LPG as a by-product.

In reality, LPG is a valuable co-product produced from gas fields and crude oil refining.

They process the gas stream from natural gas fields to separate the gases present.

These include methane, ethane, propane, butanes and pentanes.

Impurities are also removed, including water.

The produced gases are each funnelled into their own supply streams.

They capture propane and butane, the two common types of LPG, and store them in their liquefied form.

The same is true of crude oil refining.

The refinery process creates many co-products.

The co-products include gasoline, diesel fuel, asphalt base, heating oil, naphtha, kerosene and LPG.

LPG is now a Renewable Energy Source

LPG is now a renewable energy source

LPG has gone from being a traditional fossil fuel to a new form of renewable energy.

Scientists have created a genetically engineered version of the common E. coli bacteria.

This version produces propane (LPG).

So, LPG is now a renewable energy.

The bacteria consume sugar.

With genetic modification, and the help of a couple of enzymes, they make propane.

The propane produced is chemically identical to regular propane.

 LPG is NOT Coal Seam Gas (CSG)

There is some confusion over what Coal Seam Gas (CSG) is and what it is not.

LPG is not CSG.

While CSG may contain various gases, typical CSG is 95% to 97% pure Methane.

LPG is not Methane.

LPG is Propane.

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The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.

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