A propane tank.
Propane is a petroleum-based product that is used in both liquid and vapor form. Propane can only be found in its liquid form when under extreme pressure or at temperatures below -45° Fahrenheit (-42.7° Celsius). When liquid propane reaches a temperature of -44°F (-42.2°C), it boils and turns into steam.
As liquid propane is an extremely cold substance, it can also be dangerous if handled improperly. Accidental misuse freezing is fast and extreme. In appearance, it is odorless, colorless, and tasteless and looks a lot like a glass of water.
A side view of a residential propane tank.
The systems use either liquid or steam propane and the two forms are not interchangeable. Heating systems, such as home heaters or kitchen appliances, burn in the vapor form of propane. Storage tanks keep the fuel under pressure and therefore in the form of liquid propane. As the propane leaves the tank and enters an unpressurized area under normal temperatures, it is converted to steam. Storage tanks should always be kept upright to keep the liquid regulated as it leaves the tank, as burning it can cause dangerous fires.
One of the most interesting uses of liquid propane is in the automotive industry. Liquefied Petroleum Gas (LPG) first appeared as a fuel for vehicles around 1913 and since then it has been mainly used in the trucking industry. As of 2009, there were no US-produced passenger vehicles that run on LPG, although consumers interested in using this fuel can get converter kits for their gas or diesel-powered cars.
There are several attributes of LPG that make it attractive. It is mainly produced in the United States, which reduces foreign dependence on fuel. It burns cleaner than gasoline and emits less toxic substances and pollutants into the air. The cost per gallon is also generally lower.
For all its positives, there are some negatives to liquid propane as a vehicle fuel. There are many reports of consumers getting hurt by splashes of it, as it can cause burns in an instant. Neither cars that run on propane nor liquid propane to move them are not as readily available, so those looking to use them should look to suppliers and take the time to put a converter kit in their cars. The fact that it’s oil-based means it’s not a renewable source, so environmentalists argue that it’s another source that will eventually run out and that isn’t completely clean yet.