What Is Propane?


Propane (also called LPG—liquefied petroleum gas—or LP gas) is a widely used fuel. It is transported and stored as a very cold liquid, and can cause a “freeze burn” or frostbite if it contacts the skin. The liquid propane is turned into a gas inside a tank or a cylinder. In its natural form, propane is colorless and odorless. To make propane easier to detect in the event of a leak or spill, manufacturers deliberately add a chemical compound to give it a distinctive smell.

Propane is flammable when mixed with air (oxygen) and can be ignited by many sources, including open flames, smoking materials, electrical sparks, and static electricity.

Propane vapors are heavier than air. For this reason, they may accumulate in low-lying areas such as basements, crawl spaces, and ditches, or along floors. However, air currents can sometimes carry propane vapors elsewhere within a building.


It is important to become familiar with the parts of your propane system so that you can take quick and appropriate action in case of a leak or other emergency. The illustration at left shows a typical home propane system.

Propane is delivered to your home as a very cold liquid and is pumped into a specially designed storage tank (A). The liquid changes to gas before it leaves the tank. Propane tanks are typically painted white or silver to reflect heat and prevent the pressure inside the tank from getting too high.

If you have an underground tank, only the cover (B) will be visible above ground.

The cover on top of the tank protects several components from weather and physical damage, including:

  • The tank shut-off valve (C), which you can close to stop the flow of propane to your home in case of a leak or other emergency.
  • The regulator (D), which controls the pressure of the propane gas coming out of the tank.
  • The safety relief valve (E), which will pop open automatically if the pressure inside the tank gets too high. The valve will close again when the pressure returns to normal.
  • The tank gauge (F), which shows the percentage of propane in the tank.

Propane flows from your tank to your home through pipes (G), most of which run underground.

You may also have a secondary pressure regulator (H) on an outside wall of your home to further adjust gas pressure.

A shut-off valve (I) in each pipe can be closed to stop gas flow to an individual appliance.

An appliance connector (J) is the final segment in the gas piping system. This specially designed flexible tube—typically 2 or 3 feet long—carries gas from a pipe to the back of an appliance (K).