How Does LPG Work?
LPG works as a fuel, providing energy. It works by generating heat for cooking, heating, hot water and as a fuel for vehicles.
LPG is stored under pressure, as a liquid, in a gas bottle.
It turns back into gas vapour when you release some of the pressure in the gas bottle by turning on your gas appliance.
Almost all of the uses for LPG involve the use of the gas vapour, not the liquefied gas.
The LPG gas is ignited and burned to provide heat energy for various applications.
This short video (8:29) explains all of the basics of LPG gas…
But there is a bit more detail to this process…
Where Your LPG Comes From
The LPG pathway to you includes drilling of wells, refining, transport, storage, vaporisation, regulators and the gas appliances themselves.
LPG comes from drilling oil and gas wells.
LPG is found naturally in combination with other hydrocarbons, typically crude oil and natural gas.
LPG is produced from natural gas processing and petroleum refining.
How LPG is Transported to You
LPG exists as either a gas (vapour) or as a liquid, when it is under a modest amount of pressure in gas bottles, cylinders, tanks and larger LPG storage vessels.
Given that gaseous LPG has a volume 270x that of liquid LPG, it is almost always transported in its more compact liquid state.
LPG (propane) can be transported in a number of ways, including by ship, rail, tanker trucks, intermodal tanks, cylinder trucks, pipelines and local gas reticulation systems.
Most homeowners receive their LPG either by exchange cylinders or tanker delivery into a large in situ tank.
For BBQs, homeowners typically take their empty gas bottle to a retailer to be refilled or for a swap refill.
How Your LPG is Stored
LPG is compressed into liquid at relatively low pressures and stored in specially built gas bottles, cylinders or tanks.
How Liquid LPG Turns to Gas (Vaporisation) – How LPG Boils
LPG liquid boils and turns back into gas vapour when you release some of the pressure in the gas bottle by turning on your gas appliance.
To boil, LPG vaporisation, the liquid LPG draws heat from the steel walls of the gas bottle which, in turn, get heat from the ambient air.
As with water, the more heat that is applied, the more rapidly it boils, vaporising at a faster rate.
So, as the steel of the bottle draws heat from the ambient air heat, cold weather will slow down the rate of vaporisation.
LPG Vaporizer – How it Works
An LPG vaporizer (vaporiser) works by adding more heat to the LPG, for a higher vaporisation rate. An LPG (propane) vaporizer is used when the steel walls of the vessel cannot provide sufficent heat to meet the required gas vaporisation load.
An LPG vaporizer can be nothing more than a serpantine coil of tubing, absorbing heat in ambient air, that the LPG passes through. Other LPG vapourizers utilise additional heat sources like a heated water bath.
Passing Through a Gas Regulator
After it leaves the bottle, the gas passes through a regulator.
Gas regulators automatically modulate high pressure gas to a maximum pre-determined limit.
LPG (propane) gas regulators reduce the LPG pressure delivered to the gas appliances from the gas bottles.
The pressure within a gas bottle can be 800-900kPa as compared to the 2.75kPa typically required.
LPG gas regulators are usually factory pre-set to the standard operating pressure for the appliances.
Pressure Relief Valve for LPG Propane Tanks & Cylinders
Arguably, the single most important safety feature of a gas bottle or propane tank is the Pressure Relief Valve, which is a propane safety valve. It’s actually a propane safety valve within a valve.
The Pressure Relief Valve is incorporated into the main gas valve on the gas bottle (propane tank), as shown in the accompanying picture.
If the pressure of the gas inside the bottle increases, as the result of a fire or other heat source, the pressure relief valve releases some of the gas to relieve the pressure.
The propane safety valve prevents pressure build up, meaning no risk of an explosion.
Using LPG in Your Gas Appliances
Outdoor gas appliances include BBQs, patio heaters, outdoor fireplaces, pizza ovens and fire pits.
Commercial and industrial usages get into the thousands of varied applications.
There are even some more exotic uses, such as LPG fuelled hot air balloons, Zamboni machines for ice rinks and use as propellant gas in various aerosol products.
When you turn on any of these gas appliances, gas flows to the appliances from the gas bottle, via the regulator.
The gas goes to a burner which may have an automatic ignition system or manual ignition.
The level of heat may be controlled by a thermostat or by a manual control valve knob.
Some even have remote controls with multiple timers and thermostats, to make use even easier.
Once lit, the burner provides the heat to make the appliance operate, as designed.
Whilst there are a number of steps to explain how LPG works, it is actually a simple and easy-to-use technology for the consumer.
LPG has a myriad of applications, many of which make life easier and more enjoyable.
Comments, questions or feedback?
The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.