LPG (liquefied petroleum gas) is propane, butane or a mixture of the two, stored and shipped as a liquid under pressure or refrigeration. Commercial propane and butane are specified internationally in ISO 9162, and automotive LPG in Europe in EN 589.
Key ISO 9162:2013 limits
| Parameter | Commercial propane | Commercial butane |
|---|
| Vapour pressure at 40 °C (gauge) | max 1550 kPa | max 520 kPa |
| C5 and heavier | max 0.2 % mol | max 2.5 % mol |
| Dienes | max 0.5 % mol | max 0.5 % mol |
| Evaporation residue | max 60 mg/kg | max 60 mg/kg |
| Copper strip corrosion | max class 1 | max class 1 |
| Sulfur | max 50 mg/kg | max 50 mg/kg |
| Hydrogen sulfide | pass | pass |
| Free water | none | none |
Source: ISO 9162:2013 sample. Automotive LPG to EN 589 adds limits such as motor octane number min 89.0 and sulfur max 30 mg/kg (IEA-AMF); the current edition is EN 589:2024.
How LPG is traded
Many seaborne LPG cargoes are traded on the loading terminal's own specification, for example the GPA 2140 specification for US cargoes, rather than on ISO 9162. The offer should name the specification, the propane and butane split, and whether the cargo is pressurised or refrigerated.
Current LPG listings