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: C₃H₈ or 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

  Note: Some numbers have been subject to rounding.

10 Important LPG – Propane Facts

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

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.