Propane Gas Storage: How is LPG – Propane Stored Safely?
LPG is stored in pressure vessels and it is almost always stored in its liquid form.
These vessels can range from small camping canisters to BBQ gas bottles to larger gas cylinders and much larger LPG tanks - bullets.
Storage depots may consist of large storage spheres or large buried tanks.
The liquefied gas can also be stored underground, in custom-built or prepared caverns.
Propane Gas Storage - LPG Gas Storage - General Guidelines
Propane gas storage - LPG storage: LPG - propane cylinders should be stored outdoors in a well ventilated area, the cylinders should always be stored upright and storage should be kept away from high traffic areas to minimise any chance of accidental impacts.
Indoor storage should always be avoided.
The gas cylinder storage area should be flat and firm, such as a concrete slab and be in a location with good drainage, as cylinders should not be allowed to remain in standing water.
The area around the cylinders should be free from any ignition sources, including electrical componentry, and the surrounding area should also be free of any flammable materials.
The cylinders should not be placed near any artificial heat source.
The valve should always be kept closed, even if you believe the cylinder to be empty.
Note: Each country has its own specific regulations regarding LPG - propane gas storage. Please consult your local standards.
LPG – Propane is Stored as a Liquid
LPG is always stored in liquid form.
It turns into a liquid by increasing the pressure on it, with or without reducing the temperature.
Compressing it into liquid is a much better and more efficient method of storage.
As a gas, it has 270x the volume of liquid LPG.
So, liquefying it is like going from a beach ball to a table tennis ball.
What Pressure is LPG Stored at?
The term “pressure” refers to the average force per unit of area that the gas exerts on the inside walls of the containment vessel.
The pressure inside of an LPG cylinder, or larger vessel, is dependent upon the temperature of the vessel.
The higher the temperature, the higher the pressure of the LPG within the cylinder.
The fill level does not affect the pressure until you run out.
The pressure of LPG (propane) goes from 152 kPa (24 PSIG or 1.5 bar) at 0ºC to 2482 kPa (360 PSIG or 24.8 bar) at 70ºC.
Please see detailed pressure chart below.
Propane Gas Storage Pressure Chart
LPG – Propane Gas Storage Comes in a Range of Sizes
LPG storage vessels start from the very tiny and go all the way to mammoth, including:
● Butane Lighters
● Disposable Butane Cartridges
● Small BBQ Bottles
● Forklift Gas Bottles - Cylinders
● Large LPG Bottles – Cylinders
● Large LPG Tanks – LPG Bullets
● Storage in Intermodal ISO Tank Containers
● Mounded Tanks – Bullets
● LPG Storage Spheres - Horton Spheres
● Underground LPG Storage Caverns
A butane lighter is arguably the smallest LPG storage vessel.
The classic disposable butane lighter contains only about 4 grams of fuel.
This will vary by the make and model of the lighter.
The fuel can be butane, isobutane or a mixture of the two.
Disposable Butane Cartridges
The 220g (≈ 8oz.) disposable butane cartridges are used in small camping stoves and other appliances.
Many of these cartridges are now equipped with a Countersink Release Vent (CRV).
The CRV is a safety feature that is designed into the cartridge.
It allows for the release of some gas in an over pressure situation, as would occur when exposed to excess heat.
This helps to eliminate any risk of explosion.
Empty butane cartridges should be disposed of properly.
Community recycling centres are the best place to take any empties.
Small BBQ Bottles
LPG gas bottles for BBQ and camping come in two main sizes: 9kg & 4kg.
There are also various smaller sizes.
There are also two common valve types:
● the standard BBQ valve in Australia is a POL valve.
● there is also a Camper valve fitted to 4kg camper cylinders. Camper valves are for appliances designed for Camper valve use.
Other countires may have other valve types.
Forklift Gas Bottles - Cylinders
The gas for forklifts is stored in two different size cylinders.
They are also made from both steel and aluminium.
Large LPG Bottles – Cylinders
LPG 45kg gas bottles – also called 45kg gas cylinders – are the most popular size gas bottles for homes and small businesses.
45kg gas bottles can be exchanged or refilled onsite via LPG tanker trucks.
A typical installation is comprised of two 45kg gas bottles.
This is so you can switch bottles while awaiting an exchange or refill of the empty.
There are also 90kg, 190kg and 210kg size cylinders, for heavier use.
These larger cylinders are always filled via LPG tanker trucks, as they are too larger to be exchanged in a practical manner.
Other countries use various similar sizes.
Large LPG Tanks – LPG Bullets
LPG gas bulk storage tank sizes for various application solutions.
These are sometimes called "LPG Bullets", “Propane Bullets” or just “Bullets”.
These LPG tanks are for commercial, industrial and agricultural applications.
Whilst vertical installation is possible, the vast majority of bullets are horizontal installations.
They range in size from ½ tonne to 40 tonnes and larger.
Storage in Intermodal ISO Tank Containers
ISO tank containers are LPG storage vessels mounted within a standardised framework.
The standardised framework is built to ISO (International Organisation for Standardisation) standards, just like a standard (closed steel box) shipping container.
Typical LPG ISO tank sizing is 6.05m (20ft) long, 2.4m wide and 2.55m high, although other sizes also exist, including 12.2m (40ft) versions.
Capacity of the 6m ISO LPG tank is 24,000-25,000 litres or around 12 tonnes of LPG.
A tank container is built to the ISO standards to be “intermodal”, making it suitable for different modes of transportation and stackable.
These containers can be used for transport by ship, rail or truck, being transferred between them without unloading/reloading the LPG cargo.
Mounded Tanks – Bullets
Placing large LPG tanks or bullets under mounded earth provides enhanced fire safety.
The mounding provides protection from any nearby fires, vandalism and sabotage.
The bullets are buried horizontally.
Some of the largest can be up to 7m in diameter and 70m or more in length.
Mounded bullets allow storage of huge quantities of LPG in a single location.
LPG Storage Spheres - Horton Spheres
A storage sphere is a very efficient and cost effective way to store LPG.
Spheres require less steel than a cylinder to hold the same quantity of LPG.
Spheres are also a good shape for pressure vessels, as they distribute the stress evenly.
Horton spheres also need less land to store the same quantity of LPG, versus bullets.
In addition, they help minimise the cost of piping and foundations, as they hold more in a single pressure vessel.
The Hortonsphere® is named after Horace Ebenezer Horton, builder of the first spherical pressure vessels, back in 1923.
Underground LPG Storage Caverns
Why would we store LPG underground?
Underground storage is a cost efficient way to store very large quantities of LPG.
Unlike above ground tanks, there is no need for refrigeration and there is no finite life span for the project.
The above ground plant and equipment is uncomplicated, requiring minimal maintenance.
The gas is typically held within the cavern by hydrostatic water pressure in the surrounding stone.
These facilities can incorporate a dedicated docking system to load and unload LPG ocean tankers.
These can be as large as VLGC class ships of up to 45,000 tonnes.
The docking system also loads smaller tankers for re-distribution to other facilities.
The picture above was taken during the construction phase of the Elgas Cavern, in Sydney.
Where Should You Store Gas Cylinders - Bottles?
A good, safe place to store a gas cylinder is outdoors, with plenty of ventilation.
Remembering that LPG is heavier than air, it should also not be stored near a pit or a drain.
They should not be stored near any ignition source, like a flame or electrical devices.
It is important that the cylinder is always stored upright.
This allows the Pressure Relief Valve to work properly.
All bottles should be treated as if they were full, with the valve remaining closed when disconnected.
Indoor Storage LPG-Propane Cylinders
We are frequently asked if you are allowed to store LPG indoors and, if so, how much?
What are Gas Bottle-Cylinders Storage Regulations?
● Storage regulations are primarily safety related and should be observed at all times.
● Indoor storage should be avoided whenever possible and limits apply.
● Gas bottles should always be stored in a well-ventilated area away from any flame, heat or other ignition source
● LPG (propane) gas bottles-cylinders must always be stored upright with valves closed, when not in use.
● Gas bottles must be prevented from falling and protected from impact and damage.
● Storage limits on quantity may apply and placarding may be required.
The flexible nature of LPG allows for storage in many ways.
The method of storage can be selected based on the quantities involved and the logistical requirements.
Regardless of how it’s stored, LPG is there when people need it.
Clean, safe and reliable energy for everyone everywhere.
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 & may not be applicable in all circumstances.