Hydrocarbons

The hydrocarbon propellants are propane (freezing point —42.1), n-butane (freezing point — 0.5) and isobutane (freezing point — 11.7). Commercial butane is always a mixture of n-butane and isobutane. Mixtures with propane in different ratios are usually used to adjust the pressure. Hydrocarbons are cheap, stable and of low toxicity, but are highly flammable.

Hydrocarbons

Hydrocarbons

They are compounds composed exclusively of carbon and hydrogen. This group includes such compounds as methane through to highly complex molecular structures such as the polyaromatic hydrocarbons. Some of the straight-chain compounds are of concern due to their effect on the peripheral nerves whereas the more aromatic compounds of concern are carcinogens. The polyaromatic hydrocarbons are to be found in many of the fossil fuels but also are formed in the combustion of these fuels. They have been shown to be widely distributed in the environment.