Propane has a short history, having been introduced in the early part of the 20th century and becoming commonplace in the late 1920s. Today, nearly all propane sold in the United States is either produced domestically or imported from neighbors Canada or Mexico.
The most ubiquitous propane tank is the 20-pound (five gallon) cylinder model, commonly used for gas grills, insect-repelling devices and on recreational vehicles. Homeowners with gas stoves and propane-powered water heaters require a larger tank, usually a bigger version of the cylinder. Another larger option for commercial and residential users is the "submarine" tank, which features a larger capacity (along with a larger footprint). Propane dealers and other industrial sites use a wide variety of larger tanks for bulk storage of propane. Although not commonplace, there is a version of the submarine tank that is specifically designed to be installed underground.
Homeowners who use a small tank for grilling purposes are able to easily refill it at a number of locations, including propane dealers, gas stations and hardware stores, among others. Filling a tank larger than the portable 20-pound cylinder requires a propane delivery in a specialized truck called a "bobtail." Propane-powered generators usually require having multiple cylinder tanks, or a submarine tank.
In many situations, using propane to heat water is a more economically feasible method than using heating oil. A popular trend is for homeowners to disconnect their hot water heater from their standard oil-burning furnace and installing an on-demand propane-powered water heater. This allows the furnace to be shut down during the warm months, leaving the task of heating water to the more efficient propane-powered device.
Though considered extremely safe, there are still risks connected with propane (as well as other flammable gasses). Propane tanks are designed for maximum efficiency and safety, but you should never attempt to repair or modify any part of a propane tank or connection. The only attaching or detaching of propane tanks you should undertake is connecting and disconnecting a small tank to a grill. A licensed professional should perform any other work attaching propane tanks and gas lines.
Propane is a flammable gas that can act as an accelerant in the event of a fire or explosion, so care must be taken when using, storing and connecting propane tanks to grills, or any other devices.