The last time you bought a new gas appliance- grill, dryer or range for example, you were likely asked what type of gas you used in your home. Liquefied petroleum gas (LPG) or natural gas are both used to power those and other household appliances,but they have different properties and will be used differently in an appliance.
Liquefied petroleum gas (LPG), is a product of crude oil distillation. It contains mostly propane, or C3H8. Propane has the nice property that, when you compress it, it condenses into a liquid. This means that it is much easier to store in a tank than natural gas, which does not easily compress.
Natural gas is just that — natural. If you sink a well in the right spot, natural gas flows out of the ground. It is mostly methane, or CH4.
Howstuffworks.com offers further explanation:
You can see the difference between natural gas and LPG most easily when you buy a gas stove. Normally, you are supplied with two sets of jets, one set for natural gas and one set for LPG. You install one jet in each burner. The jet is simply a little screw-in cap with a hole drilled into it. The difference is that the hole in the jet for natural gas is bigger — about twice as big — as the hole in the jet for LPG.
The reason for this difference is because LPG contains much more energy than natural gas. A cubic foot of natural gas contains something like 1,000 BTU (British Thermal Units) of energy. A cubic foot of propane contains perhaps 2,500 BTU. You can see that if you take a gas appliance set up for natural gas and then run it on LPG, the appliance is going to run more than twice as hot. In the case of a water heater , it is apparently hot enough to start a fire.
So, the seemingly simple question of what type of gas fuels your home, can be an important piece of fire safety information for protecting you and your family.