What is liquefied petroleum gas?

	Liquefied petroleum gas, or LPG for short, is a mixture of two gases: Butane Propane About 60% of LPG is extracted from the ground or seabed as natural gas, while the rest is produced in the gasoline refining process.
	The gas is then compressed enough to become a liquid that can be stored in small tanks and then gradually released to provide energy. Propane takes up about 270 times less space and butane takes up about 230 times less space when compressed, meaning LPG is easy to carry and lasts for a long time.
	When using LPG, the regulator ensures that gas is released safely and evenly from the cylinder through the valve. At this stage, it again turns from a liquid into a vaporous gas.
	Since LPG is almost odorless, manufacturers add chemicals to create a characteristic odor in the event of a leak.
	In the UK, propane is usually stored in red tanks and butane in blue. Green tanks, often referred to as patio gas, usually contain a mixture of butane and propane. However, colors may vary in other countries.
	Butane gas is commonly used for small household appliances such as portable heaters or outdoor appliances such as stoves and barbecues in summer. It is less toxic than propane, so it can be legally stored indoors. However, it does not burn very well in cold conditions - below 0°C - so it is often mixed with around 20% propane, which will operate at much lower temperatures.
	Propane has a boiling point (the temperature at which it changes from liquid gas to vapor and can be used) -42°C. This means that unless you live somewhere like the North Pole, you can use it all year round. Propane remains in liquid form due to the pressure inside the tank and becomes a gas again when it is released from the tank and returned to atmospheric pressure.
	Propane's cold-weather ease of use makes it popular with caravaners and an ideal fuel for household outdoor heating tanks, vehicles, gas burners, large barbecues, and other appliances that require a powerful yet portable heat source. However, it is toxic, so it must always be kept outside.
	Many gas cylinders are made of steel. This is because strong metal is needed to withstand the varying pressures and temperatures that occur inside the canister, but this makes them very heavy and difficult to move.
	However, lighter containers are becoming more common and many are now made from aluminium, fiberglass or plastic. These lightweight tanks are especially suitable for caravans, as they will not significantly increase the weight of the vehicle at the nose or make it unbalanced at the front.
	Translucent or transparent containers are becoming more and more common. They are usually made of fiberglass or plastic and roughly indicate how much gas is left inside.
	Some cylinders come with a pressure gauge that allows you to check the gas level and acts as a leak detector. You can also buy them separately to add on. Not all regulators have a gauge port, but adapters are available for purchase. For more information see: What gas regulator accessories are available?
	Another useful accessory is the gas level indicator, which attaches magnetically to the side of the tank. As the gas is used up, the temperature inside the cylinder begins to drop. The liquid crystals in the indicator react to this by changing color, indicating when to think about refueling.
	You can also purchase ultrasonic gas level indicators that use the same technology used in medical ultrasound scanning. There are various designs on the market, but they all work by directing an electron beam into a cylinder. Part of the beam is reflected, and this indicates whether there is liquid gas left in the tank at that moment.
	If there is no liquefied gas, the LED indicator (light emitting diode) will turn red, and if the device detects liquefied gas, it will turn green. Be careful to keep the indicator horizontal or the beam will be directed at an angle through the tank and you may get false readings.