What is the Difference Between Propane and Butane?
Propane and butane are two very similar gases, both used widely for fuel, especially for heating fuel. Although proponents of each gas hold theirs to be the superior gas for a number of reasons, each have benefits and disadvantages. Ultimately, their similarities outweigh their differences, and the choice of which one to use is largely a matter of personal taste of which gas fits a specific need best.
Both propane and butane are derived from petroleum, either from oil or natural gas. Propane is a three-carbon alkane, consisting of three carbon atoms and eight hydrogen atoms, while butane is a four-carbon alkane, with four carbon atoms and ten hydrogen atoms. Both have much the same reaction when combusted, releasing water and carbon dioxide when they burn under ideal conditions, and when oxygen is limited they may also produce amounts of soot and carbon monoxide.
Propane is by far the most common of the two gases in North America, and is seen as a fuel to heat houses, and also for a number of portable purposes. Often propane is used to fuel things like barbecues, or camping stoves or lanterns. Propane can also be used to fuel vehicles, in which case it is often mixed with small amounts of things like butylene, propylene, and butane, and it is referred to as liquefied petroleum gas, or LPG. Ethanethiol is often also added to propane, to act solely as an odorant, so that people can detect a gas leak, as propane is naturally odorless. Propane is represented in the NFPA-704 system with a 4 in the red diamond, a 0 in the yellow diamond, a 1 in the blue diamond, and nothing in the white diamond.
Butane, while not as commonly used as propane, is nonetheless a very popular heating fuel. Butane is also used in things like camp stoves, and is also seen in many cigarette lighters, and as a propellant in some aerosols. It is represented in the NFPA-704 system in the same way as propane, and like propane is also classified as highly flammable (F+). Butane is, generally speaking, a cheaper fuel than propane, although since it is less common it is not always possible to easily find devices fitted to work with butane tanks.
On a per-volume basis, butane is a more efficient fuel than propane, by around 12%. This means that a similar amount of butane and propane will yield more energy for the butane. For many backpackers, especially those trying to pack as lightly as possible, this 12% advantage makes butane the ideal fuel. Coupled with the slight price difference, butane often wins in a head-to-head comparison.
On the other hand, propane has a lower boiling point than butane, and is stored at a higher pressure point. This means that propane is much better equipped to deal with the elements and brutal weather, making it a superior choice for long-term storage outside. It also means those hiking in especially rough environments are more likely to choose propane. Butane is not recommended for storage in anything below freezing, so anyone camping in the snow or freezing environments is much more likely to take along propane canisters.
Written by Brendan McGuigan
