Propane exists as a liquid and a gas. At atmospheric pressure and temperatures above -44 F, it is a nontoxic, colorless and odorless gas. Just as with natural gas, an identifying odor is added so it can be readily detected. When contained in an approved cylinder or tank, propane exists as a liquid and vapor. The vapor is utilized from the container as a clean-burning fuel gas.
Propane is 270 times more compact as a liquid than as a gas, making it economical to store and transport as a liquid.