Key properties of natural gas include the following:
- Gas is tasteless, colorless, odorless, and non-toxic (gas is odorized after it enters the delivery system so that leaks are noticed, see odorization for more information)
- While gas is non-toxic, it can result in suffocation by displacing oxygen in confined spaces such as trenches or vaults
- It is gaseous at normal atmospheric temperatures and pressures
- Gas can be liquefied by cooling to about -260 degrees Fahrenheit (-162 °C)
- Gas is lighter than air, so rises when vented in air
- Gas is compressible, meaning that it can be “squeezed” to raise the pressure
- Gas expands when heated and contracts when cooled
- When gas is liquefied it contracts significantly, by about a factor of 600
- As show in the graphic below, combustion occurs only when the air-to-fuel ratio is 5 to 15%. If the air-to-fuel ratio is above or below this range, gas will not light.