The LPG family
Two hydrocarbons make up the bulk of LPG:
- Propane (C3H8) — the dominant US residential fuel. Liquefies at ~120 psi at 70°F. Boiling point -44°F.
- Butane (C4H10) — used more in industrial and refrigerant applications. Liquefies at lower pressure (~30 psi). Boiling point ~32°F, making it less practical for cold-climate heating.
Where LPG comes from
Same two sources as propane alone: natural gas processing (the primary source globally) and crude oil refining. Approximately 60% of global LPG comes from natural gas processing, 40% from refining. The US is currently the world's largest LPG exporter, shipping propane to Asia, Latin America and Europe.
LPG vs natural gas
LPG is delivered as a liquid in pressurized tanks; natural gas flows as low-pressure vapor through utility pipelines. LPG works anywhere a truck can reach; natural gas only works inside utility distribution territories. See propane vs natural gas.
International terminology
In Europe, Asia and Latin America, 'LPG' typically refers to a propane-butane blend with seasonal mix variations. In the US, 'LPG' and 'propane' are interchangeable because the US market sells essentially pure propane (HD-5 grade, minimum 90% propane content). See propane quality and grades.
FAQ
Is LP gas the same as propane?
In the US, effectively yes. Both refer to C3H8 propane. The 'LP' acronym is a holdover from older industry terminology; consumers and dealers use 'propane' more often today.
Why is LP gas stored as a liquid?
Liquid propane occupies 1/270th the volume of vapor, making storage and transport vastly more efficient. The pressure (~120 psi at 70°F) is modest enough for steel tanks to handle safely.