Last reviewed 22 July 2020
Gordon Tranter considers the advantages of using liquefied petroleum gas and the safety considerations that must be taken into account by any organisation that uses and stores LPG.
What is LPG?
Liquefied petroleum gas (LPG) is a convenient and clean alternative to gas, which has many applications such as space and process heating, as a refrigerant, for cutting, welding, powering machinery, water heating, powering industrial ovens, kilns or furnaces, or fuelling combustion engines, particularly fork-lift trucks. It is particularly useful for cooking and heating in remote places where ordinary gas supplies are unavailable.
LPG is composed of either of the flammable but non-toxic gaseous hydrocarbons — propane and butane — or a mixture of both. The gas is compressed to turn it into liquid form to reduce its volume to facilitate handling. Because of their different properties, the two hydrocarbons are each suited to specific uses. Propane’s lower boiling point suits outdoor storage and is primarily used for central heating, cooking and numerous commercial applications. Butane, which doesn’t work in colder conditions, is best used indoors and is better for powering indoor portable heaters.
What are the advantages of LPG?
LPG is a clean-burning, sustainable and efficient fuel, a reliable energy supply that is flexible and efficient. It produces less air pollutants, particularly black carbon emissions formed through incomplete combustion, and carbon dioxide than most other fuels. Its combustion emits 33% less carbon dioxide than coal and 15% less than heating oil. Consequently, it helps in the efforts to reduce global warming and does not carry the health risks associated with some other fuels. LPG has a higher efficiency than other fuels due to its high calorific value. Its numerous applications range from use as a domestic heating fuel to fuelling fork-lift trucks, furnaces and portable generators.
Containers for LPG
LPG is supplied in a variety of containers that are pressurised to keep the LPG liquefied. These include bulk storage tanks, cylinders of various sizes and disposable canisters, which allow it to be stored, transported and used in different ways depending on its intended use.
The hazards of LPG
The greatest hazard in working with LPG is that, when mixed with air, it can burn or explode if there is a source of ignition. It is approximately twice as heavy as air when in gas form and tends to sink towards the ground. It can flow for long distances and can collect in drains and basements, where it could present a fire or explosion or suffocation hazard.
LPG cylinders exposed to fire can be pressurised to the point where the pressure relief valve opens, causing a dangerous jet of burning gas. Cylinders can also explode in the extreme heat of a fire, throwing debris far and wide. A container that has held LPG and is “empty” may still contain LPG in vapour form and is thus potentially dangerous.
The vaporisation of LPG in liquid form can cause severe cold burns to the skin similar to frostbite and can also cool equipment so that it may be cold enough to cause cold burns. Although non-toxic, leakage of LPG, for example from valves or pipe connections, can displace air and cause asphyxiation. LPG does contain a powerful odorant so that leaks can be detected easily. The use of LPG cylinders may involve manual handling and the risks associated with this.
Any manager responsible for premises where LPG is used has responsibilities to protect against risks to health and safety under the Health and Safety at Work, etc Act 1974 and its subsidiary legislation.
Precautions — fire and explosion
For work situations in which a dangerous substance is present and presents a risk to physical safety from fire or explosion, the Dangerous Substances and Explosive Atmospheres Regulations 2002 must be applied. A risk assessment of any work activities involving LPG must be carried out, and technical and organisational measures to eliminate or reduce, as far as reasonably practicable, the identified risks must be provided.
The following procedures should be adhered to when LPG is used.
Combustible material, such as rubbish, should be kept well away from the cylinders. Chlorate-based weedkillers can be a fire hazard and should not be used near LPG storage areas.
Sources of ignition, such as electrical equipment, vehicles or bonfires, should be kept away from the LPG. Smoking near LPG, particularly when changing cylinders, should be prohibited and there should be “no smoking” signs where LPG is stored and used.
LPG cylinders should not be exposed to excessive heat, eg they should be protected from hot sunlight.
Refillable LPG cylinders should be considered to be full whatever the state of their contents.
Steps should be taken to avoid leaks. Cylinder valves and all connections should be checked for leaks. If possible, cylinders should be isolated by closing the cylinder valve whenever the appliance is not in use. Cylinders should be stored so that they cannot be damaged by, for instance, vehicles or intruders. Do not store LPG indoors and ensure good ventilation when it is used indoors.
Procedures should be in place in case of a fire or a leak, which should include the following actions:
evacuating the premises to a safe place well away from the installation
dialling 999 to call the fire brigade from a safe location, and ensuring they are told LPG cylinders are on the premises
activating the fire alarm if available
turning off all the LPG appliances if this can be done safely
contacting the LPG supplier to make safe any leak at a cylinder or the associated pipework
contacting a Gas Safe registered gas fitter to make safe any LPG appliance that is leaking or is not working properly
opening all the doors and windows where a leak is indoors
avoiding switching on or off any electrical equipment as this may cause a spark.
Precautions — health effects
The possibility of a situation in which LPG could displace air and cause asphyxiation should be considered and, where likely, a risk assessment carried out under the Control of Substances Hazardous to Health Regulations 2002, to assess the risks and to identify the measures needed to prevent such incidents.
Training of staff involved in the handling and use of LPG should include information about the risks of vaporisation of LPG causing severe cold burns to the skin, and that in certain situations it can also cool equipment so that it may be cold enough to cause cold burns. Personal protective equipment (PPE) should be provided in situations where such burns can occur, such as changing fork-lift truck LPG cylinders.
Maintenance of LGP appliances
LPG containers and associated fittings and pipework should be considered as work equipment, and the Provision and Use of Work Equipment Regulations 1998 applied. LPG appliances will require maintenance and regular inspection. LPG bulk tanks and fittings are usually the supplier’s property and they will be responsible for regular maintenance. For cylinders, there may be a maintenance contract with the LPG supplier or a maintenance company; for leased cylinders the cylinders’ owner usually carries out the maintenance. In either case, the manager should ensure the arrangements are clear and the maintenance is carried out at the specified intervals.
Storage of LPG cylinders
Failure to store LPG cylinders correctly can have devastating results. Recommendations for the storage of LPG cylinders are described in the UK LPG Trade Association’s Code of Practice 7: Storage of Full and Empty LPG Cylinders and Cartridges. The main considerations are:
storing away from combustible materials
storing cylinders accessibly at ground level
not storing close to occupied buildings
storing at least three metres away from other cylinders like oxygen, chlorine and ammonia
storing cylinders in a vertical position
having a written procedure to deal with emergencies
providing appropriate fire extinguishers
displaying notices such as “LPG — Highly Flammable”, “NO SMOKING” or “NO NAKED FLAME”.
It is important that there are security arrangements to prevent unauthorised access, particularly by intruders.
Bulk storage tanks
LPG bulk storage vessels are used either above or below the ground at sites where there is a large usage of LPG, eg central heating or cooking or filling LPG powered fork-lift trucks. Recommendations for bulk LPG storage are available in the UK LPG Trade Association’s Code of Practice 1: Part 1 Bulk LPG Storage at Fixed Installations (in four parts).
There should be a minimum distance (the separation distance) between the tank and any building, boundary line or fixed source of ignition. Minimum separation distances for the maximum LPG capacity of the tank are available on HSE’s website (https://www.hse.gov.uk/gas/lpg/separationdistances.htm).
If possible, the tank (and its associated piping) should not be located in an area where there is motor traffic. Where this is not possible, there should be protection, such as crash barriers or bollards, to protect the tank from being hit by a motor vehicle.
Under the Pressure Systems Safety Regulations 2000, fixed LPG storage systems and associated fittings require a written scheme of examination. For those premises where part is used for domestic or residential purposes or as sleeping accommodation, the Gas Safety (Installation and Use) Regulations 1998 apply to LPG storage vessels and pipework in the same manner as they apply to natural gas. Regular maintenance and safety checks at least once every 12 months carried out by a Gas Safe registered engineer must be arranged for all LPG appliances provided for tenants.
In May 2004, a gas leak from a corroded, buried pipe from an LPG tank led to an accumulation of gas in the basement of a Glasgow plastics factory. This resulted in an explosion that caused the building to collapse — 9 people were killed and 33 were injured, some critically. To reduce the risk of another incident, the UK LPG industry and the Health and Safety Executive (HSE) strongly advise that underground metallic pipework should be replaced with pipework made from a non-metallic material, such as polyethylene, which will not corrode.
LPG is safe if used correctly. However, if stored or used incorrectly, it can be extremely dangerous. Those responsible for their storage and use need to ensure that LPG containers and associated appliances are maintained, stored, handled and used safely.