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10 Most Common Flammable Solids
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Flammable solids are materials that ignite easily and burn quickly when they come into contact with heat, sparks, or open flames.
These materials pose a significant fire hazard because once they catch fire, the flames can spread rapidly and be difficult to control.
From everyday items like matches and firelighters to more industrial materials like metal powders and phosphorus, these solids are present in many aspects of life.
That’s why it is essential to understand how they behave, how to store them safely, and what to do in an emergency.
This article explores the definition of a flammable solid, introduces ten of the most common examples, and offers practical safety tips to help reduce fire risks at home and in the workplace.
What is a Flammable Solid?
A flammable solid is a material that can easily catch fire and burn rapidly when exposed to heat, sparks, friction, or an open flame.
These substances are classified as Class 4 hazardous materials under international transport and safety guidelines because of their high risk of ignition and fire spread.
Flammable solids can be found in many forms, powders, granules, sheets, or even everyday products like matches and firelighters.
Some are naturally combustible, while others become dangerous when exposed to air, moisture, or certain chemicals.
They are often used in industrial processes, laboratories, manufacturing, and even in household products, making them more common than many people realise.
The main danger with flammable solids lies in how quickly they can ignite and how fiercely they can burn.
For example, powdered metals like aluminium or magnesium can burn extremely fast and even explode when airborne.
Others, like phosphorus or alkali metals, can self-ignite when exposed to air or water.
Flammable solids are grouped into three categories for safety purposes:
- Division 4.1: Flammable solids (e.g. matches, sulphur)
- Division 4.2: Substances liable to spontaneous combustion (e.g. phosphorus)
- Division 4.3: Substances that emit flammable gas when in contact with water (e.g. sodium)
Because of their fire risk, these materials must be stored, handled, and transported with extreme care.
Understanding what flammable solids are, and how they behave, is key to preventing dangerous fires and accidents.
10 Most Common Flammable Solids
Flammable solids are materials that catch fire easily and burn rapidly.
They are found in homes, workplaces, and industries, and can become extremely dangerous if handled carelessly.
Below are ten of the most common flammable solids, including how they behave and why they require careful attention.
Alkali Metals
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Alkali metals include elements such as lithium, sodium, potassium, and rubidium.
These metals are highly reactive and are known to ignite spontaneously in air or explode on contact with water.
When exposed to moisture, alkali metals produce hydrogen gas and heat, which can cause immediate ignition.
For example, a small piece of sodium dropped into water will fizz, spark, and potentially explode.
These reactions are not just spectacular, they are highly dangerous.
Alkali metals are used in batteries, research labs, and chemical manufacturing.
Because of their reactivity, they are stored under oil or in sealed containers to prevent exposure to air or water.
Celluloid
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Celluloid is one of the earliest types of plastic, made by combining nitrocellulose with camphor.
It was once used widely in film reels, combs, toys, and even dentures.
However, celluloid is highly flammable and can ignite from just a small amount of heat or friction.
When it burns, it produces a fast, intense flame that is difficult to control.
Early cinema fires were often caused by celluloid film catching fire under the heat of a projector bulb.
Today, celluloid has been largely replaced by safer materials, but it still appears in some vintage items.
It should always be kept away from heat and stored in well-ventilated areas.
Coal
Coal is a black or brownish-black rock made of carbon-rich material.
It has been used as a fuel source for centuries, particularly in power stations, homes, and industrial processes.
Although solid coal is relatively stable, coal dust is extremely flammable.
Fine coal particles suspended in air can create explosive mixtures, especially in enclosed spaces like mines or silos.
Fires involving coal are hard to extinguish once started.
They can smoulder deep within coal piles for days or weeks.
Good ventilation and dust control are essential in environments where coal is stored or used.
Firelighters
Firelighters are small blocks or cubes made from flammable substances such as paraffin wax, kerosene, or compressed wood and oil.
They are designed to catch fire easily and help light barbecues, wood burners, or campfires.
While firelighters are very useful, they must be handled with care.
Storing them near open flames or in high temperatures can lead to accidental fires.
Some types release flammable vapours that can ignite suddenly.
Always store firelighters in a cool, dry place and use them as instructed.
Keep them out of reach of children and never use them to revive a dying fire, they can flash back dangerously.
Matches
Matches are perhaps the most familiar flammable solid.
They consist of a small wooden or cardboard stick tipped with chemicals that ignite when struck.
The match head typically contains potassium chlorate, sulphur, and other substances.
When struck against the matchbox surface, friction produces enough heat to ignite the chemicals and start a flame.
Because they are so easy to light, matches are considered hazardous goods.
They should be kept in their original packaging, stored away from heat, and handled responsibly.
Used matches should be fully extinguished and disposed of safely.
Metal Powders
Fine metal powders such as aluminium, magnesium, titanium, and zirconium are highly flammable, especially when dispersed in air.
These powders are used in fireworks, pyrotechnics, welding, and metal finishing.
When airborne, they can form explosive mixtures that ignite with a single spark.
Magnesium powder, for example, burns at extremely high temperatures and can cause severe burns or fires.
To reduce the risk of explosions, metal powders must be stored in tightly sealed containers in non-sparking environments.
Dust should be cleaned using specialised vacuum systems, and equipment should be grounded to prevent static electricity.
Phosphorus
Phosphorus exists in several forms, but white phosphorus is the most flammable.
It ignites spontaneously in air and burns with a bright, white flame.
Because of this, white phosphorus is stored underwater or in sealed containers to prevent exposure to oxygen.
Phosphorus is used in military applications, chemical manufacturing, and fertilisers.
It’s also found in small amounts in some matches and fireworks.
Even brief contact with white phosphorus can cause serious burns.
It also releases toxic fumes when it burns, making it dangerous to inhale.
Red phosphorus is more stable but can still ignite under friction or heat.
Seed Cake
Seed cake is the solid by-product left after oil is extracted from oil-rich seeds, such as linseed, sunflower, or cottonseed.
Although it may look harmless, seed cake can catch fire spontaneously during storage.
Residual oils within the cake can oxidise over time, generating heat.
If the heat isn’t allowed to escape, due to poor ventilation or compact storage, it can build up until the seed cake catches fire on its own.
Seed cake is often used as animal feed or fertiliser.
It must be stored in cool, dry conditions and checked regularly for signs of heating or smoke.
Fires in seed cake storage can spread quickly once started.
Sodium Batteries
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Sodium batteries are known for high energy storage but also come with fire risks.
They contain sodium metal, which reacts violently with water and moisture.
If the battery casing is damaged or the battery overheats, the sodium can ignite, causing intense fires.
In worst cases, the battery may explode or leak hot, flammable materials.
Sodium batteries are used in large-scale energy storage and some newer electric vehicle concepts.
Because of their high energy and fire potential, they require robust safety systems, temperature controls, and fire-resistant housing.
Sulphur
Sulphur is a yellow, non-metallic element found in nature and used in many industrial processes, including the production of sulphuric acid, fertilisers, and matches.
When heated, sulphur melts into a reddish liquid and eventually ignites, burning with a blue flame and producing sulphur dioxide gas.
This gas is toxic and irritating to the eyes, nose, and throat.
Sulphur fires can be difficult to put out and produce large amounts of smoke.
In powder form, it poses an even greater fire risk, as it can ignite easily and burn rapidly.
To handle sulphur safely, store it in well-ventilated areas away from heat or open flames, and avoid creating dust clouds when moving or processing the material.
How to Protect Yourself from Common Flammable Solids
Flammable solids can pose serious fire hazards if not handled with care.
Whether you’re working with these materials in an industrial setting or storing them at home, following simple safety steps can reduce the risk of accidents.
Store Properly
Keep flammable solids in cool, dry, and well-ventilated areas.
Avoid places with direct sunlight, heat sources, or open flames.
Always store materials in containers specifically designed for hazardous goods, and ensure lids are sealed tightly to prevent spills and contamination.
Use the Right Equipment
When handling flammable solids, wear appropriate personal protective equipment (PPE).
This includes gloves, eye protection, flame-resistant clothing, and sometimes respirators if there is dust or fumes.
Using the right tools, such as non-sparking scoops or containers, can also help prevent accidental ignition.
Separate Incompatible Materials
Some flammable solids react dangerously with other substances, including water or certain chemicals.
Keep incompatible materials stored separately and clearly label all containers.
Consult safety data sheets (SDS) for guidance on proper segregation.
Prevent Dust Buildup
Fine powders like metal dust or coal can ignite easily when dispersed in air.
Regularly clean work areas to prevent dust accumulation, and avoid sweeping, which can stir up particles – use a vacuum with a HEPA filter instead.
Train and Educate
Make sure everyone handling these materials receives proper training.
Staff should know how to store, handle, and dispose of flammable solids safely.
Emergency procedures should be clearly displayed, and fire extinguishers or other firefighting tools should be easily accessible.
Conclusion
You should now have more of an understanding of common flammable solids.
Flammable solids present serious fire risks, especially when they are mishandled, stored incorrectly, or exposed to heat, sparks, or open flames.
Each flammable solid has unique properties, ignition points, and hazards.
Some, like celluloid or metal powders, can ignite with friction or static discharge.
Others, such as seed cake or coal, may combust spontaneously under the right conditions.
Being aware of these differences helps individuals and businesses store and handle these substances more responsibly.
By respecting the dangers and taking the right precautions, we can use these materials safely and avoid potentially life-threatening incidents.
What really caused the Heathrow blackout? NESO’s North Hyde Substation report reveals overlooked warning
Incident at North Hyde Substation caused widespread disruption in March
The National Energy System Operator (NESO) has published its final report on the North Hyde Substation fire, confirming that a transformer fault at the 275kV site led to a major outage on 20 March.
According to NESO, the failure resulted in the loss of all electricity supply from the substation, directly affecting 66,919 customers and causing operational disruptions at Heathrow Airport and other critical services.
The outage also impacted road and rail networks, Hillingdon Hospital, three data centres and thousands of homes and businesses across the area.
Residents living near the site were evacuated, with some requiring alternative accommodation during emergency response efforts.
NESO stated that power restoration for affected domestic and commercial customers supplied by SSEN Distribution occurred within expected timeframes.
Forensic analysis identified cause of fire at 275kV site
NESO reported that a forensic investigation by National Grid Electricity Transmission and the London Fire Brigade identified a transformer fire as the source of the incident.
According to the report, the fire originated from a high voltage bushing failure, which was most likely caused by moisture ingress leading to an electrical fault.
Elevated moisture levels had been recorded in the bushing oil sample in July 2018, but NESO noted that mitigating measures were not implemented in response to the finding.
National Grid Electricity Transmission has since committed to a full review of its oil sampling procedures and is reviewing all historical oil sample records for appropriate follow-up actions.
The organisation stated that it aims to ensure the robustness of its asset condition monitoring practices.
Heathrow Airport’s internal network limitations extended power loss
NESO’s report concluded that the configuration of Heathrow Airport’s internal electrical network contributed to extended disruption at the site following the loss of one of its three supply points.
Heathrow Airport Limited’s contingency plan involves switching to the two other operational supply points, a process estimated to take 10 to 12 hours.
This plan was not widely known outside of the airport’s technical team and had not been communicated to energy providers.
The airport was closed for most of 21 March to complete the reconfiguration and safety checks.
It reopened later that day for limited flights and resumed full operations on 22 March.
Energy sector lacks visibility of critical infrastructure links
The review found that energy network operators are generally unaware of whether customers on their systems qualify as Critical National Infrastructure (CNI).
NESO reported that there is no requirement in the current regulatory framework for CNI operators to confirm continuity arrangements in the event of a power failure.
It also stated that CNI customers do not receive priority status under existing electricity regulations.
The government is leading a programme of work to map and analyse CNI interdependencies across sectors.
NESO said the findings point to a need for improved collaboration and data sharing between infrastructure operators and electricity networks.
Twelve recommendations issued to support future energy resilience
NESO set out 12 recommendations aimed at reducing the risk and impact of similar incidents in future.
The recommendations cover a range of themes including asset management systems, maintenance action protocols and fire risk assessment processes.
Other areas include accessibility for emergency responders, resilience of sites with multiple power sources, and updates to Electricity Safety, Quality and Continuity Regulations (ESQCR).
Additional recommendations address incident management, visibility of site-wide risk, and the resilience of Critical National Infrastructure.
NESO Chief Executive Officer Fintan Slye said: “NESO’s final report into the North Hyde Substation outage sets out the root cause and a clear set of recommendations to further improve the resilience of Great Britain’s energy system, and the resilience of its critical national infrastructure.
“The power outage and closure of Heathrow airport were hugely disruptive and our report seeks to improve the way parties plan for and respond to these incidents, building on the underlying resilience of our energy system.
“All parties involved are focussed on working together to deliver these important recommendations and much of this work is already underway with NESO’s full support.
“I would like to thank all the organisations who have provided evidence to the review for their cooperation.”
North Hyde Substation fire triggers national energy resilience review: Summary
NESO published its final report on the North Hyde Substation outage on 7 July 2025.
The incident occurred on 20 March 2025 and resulted in the loss of power from the 275kV substation.
Heathrow Airport and other critical services were affected.
A total of 66,919 customers were impacted, according to SSEN Distribution.
Residents near the site were evacuated during the response.
Forensic analysis attributed the fire to a transformer bushing failure.
Moisture ingress caused an electrical fault that triggered the fire.
Elevated moisture levels were previously detected in 2018.
National Grid Electricity Transmission has launched a review of its sampling process.
NESO found limitations in Heathrow Airport’s internal power network design.
The airport was closed for most of 21 March to reconfigure its power supply.
NESO highlighted a lack of awareness around CNI status among energy providers.
Twelve recommendations have been made to support future energy resilience.
Augwind unveils commercial AirBattery in Germany
Israel-based Augwind to deploy energy storage system in Germany
CleanTechnica has reported that Israel’s Augwind Energy will construct the world’s first commercial-scale AirBattery energy storage system in Germany.
The project will use compressed air stored in underground salt caverns to provide electricity during periods of low renewable generation.
This type of long-duration energy storage is designed to complement intermittent energy sources like wind and solar.
The compressed air will be generated using surplus renewable energy from the grid.
Or Yogev, Founder and CEO of Augwind Energy, discussed the initiative with CleanTechnica in a recent interview.
The system will store energy for several months
The company explained that the AirBattery will be able to store compressed air for up to several months.
Yogev said: “We can store energy for up to several months – a game-changing capability for addressing Germany’s ‘Dunkelflaute’ periods when solar and wind output is low.
“Our system has unlimited duration potential, limited only by the volume of the cavern itself.
“This long-duration storage capability is exactly what Europe needs as renewable energy penetration exceeds 50%.”
The compressed air is stored in solution-mined salt caverns, which are naturally airtight due to their density and pressure.
Yogev said: “The salt in the deep underground is highly condensed and pressurised by the weight above it.
“It is so dense that it is completely airtight.
“This unique characteristic has led to the use of solution mined salt caverns for safely storing compressed natural gas for over half a century.”
Installation timeline and turbine generation capacity
The AirBattery system will require between 9–12 months for installation and an additional 3–6 months for commissioning once permitting is finalised.
The facility will include 3 or 4 turbines, capable of generating between 3–10 MW of electricity on average.
Yogev said: “The turbines will be similar to the highly efficient Voith Hydro turbine currently operating in our demonstration site.”
To improve power quality and responsiveness, the system will be integrated with lithium-ion batteries.
Yogev added: “We couple the system with short-duration lithium-ion batteries for ancillary services and to provide a high-quality power profile.”
While the startup speed is slower than lithium-ion, the integration allows rapid deployment when needed.
Commercial model and system costs
The total cost of the first module will depend on the specific cavern selected and is expected to range between €7 million and €15 million.
AirBattery’s projected cost per kilowatt-hour for multiweek storage is estimated at 10–15 USD.
Yogev said: “Our AirBattery technology offers exceptionally competitive economics at 10–15 USD per kWh for multiweek duration storage.
“This cost-effectiveness, combined with our minimal environmental footprint and use of locally sourced materials rather than critical minerals, makes AirBattery the clear choice for Germany’s energy transition needs.”
The system is designed to work with wind and solar electricity that would otherwise be curtailed due to grid oversupply.
Augwind intends for this approach to reduce reliance on imported energy sources.
Yogev explained: “We’re taking excess renewable electricity that would otherwise be wasted during periods of oversupply and storing it for when Germany needs it most.”
Deployment partners and market role
The company is currently finalising partnerships with various stakeholders including energy traders, utilities, cavern owners, and industrial customers.
Although the names of participating partners have not yet been confirmed, Augwind says that demand from the German energy market has been strong.
Yogev said: “Our goal is to become Europe’s preferred partner for multiweek storage solutions, and this German launch will demonstrate that long-term energy storage is not only technically feasible but economically sound.”
The project’s final capacity will depend on the specific geological site selected.
Each AirBattery cavern could store compressed air equivalent to 3–8 GWh of electrical output, according to the company.
The exact figure for the first site has not yet been confirmed.
Germany to install first commercial AirBattery system: Summary
Augwind Energy has announced plans to build a commercial AirBattery system in Germany.
The system will store compressed air in underground salt caverns to generate electricity.
Air will be compressed using surplus wind and solar energy.
The company said each unit may store 3–8 GWh depending on site conditions.
Compressed air can be stored for several months.
The project cost will range between €7 million and €15 million.
The installation phase will last 9–12 months, followed by 3–6 months for commissioning.
The system will use 3 or 4 turbines generating 3–10 MW.
Lithium-ion batteries will support the system for ancillary services.
Projected storage cost is 10–15 USD per kWh.
No specific customers have yet been named.
The project aims to support Germany’s long-duration storage needs.
India factory fire kills 39 as Sigachi shuts plant operations
Fire kills at least 39 at Indian pharmaceutical supplier
At least 39 people have died following a fire and explosion at a chemical manufacturing site operated by Sigachi Industries in southern India, according to CNN and Reuters.
The incident occurred on Monday at the company’s plant in Telangana and left 34 people injured.
Local officials reported that more than 140 workers were present when the explosion occurred.
District administrative official P. Pravinya said 25 of the deceased remained unidentified as of Tuesday.
Operations at the facility have been suspended for 90 days, Sigachi Industries confirmed.
Investigation launched by Telangana government
The Telangana state government has announced the formation of a five-member committee to examine the cause of the explosion.
The company has not yet disclosed the cause of the incident.
GV Narayana Rao, director of Telangana fire disaster response service, told Reuters that the building was completely destroyed.
Rao said: “We are still clearing the debris.
“Once we are all done with the clearing, only then we will be able to assess if any other body is still remaining under the debris or if it is all clear.”
According to the fire department, recovery efforts are ongoing at the site.
Sigachi employee recounts incident
Factory worker Chandan Gound described the explosion in an interview with Reuters.
Gound said: “I came out (of the plant) to use the restroom and heard a loud blast. It sounded like a bomb blast. I came out and saw fire. A part of the fire also spread towards me. I jumped the wall and escaped.
“Many of them (those inside) managed to escape, but a large number were trapped and could not come out.”
Gound had been employed at the site for six months.
Authorities have not released the full list of those affected by the fire.
Company shuts plant and initiates claims
Sigachi Industries has confirmed that it has halted operations at the Telangana site for 90 days, citing structural and equipment damage.
The company said the facility is fully insured and it is in the process of submitting insurance claims.
Sigachi’s Telangana plant contributes over a quarter of its total annual production capacity, which is 21,700 million metric tons.
Following news of the incident, Sigachi’s stock fell by approximately 8 percent on Tuesday.
The company reported that this represented its steepest two-day decline on record.
Separate factory fire kills five in Tamil Nadu
CNN and Reuters also reported a separate incident on Tuesday in Tamil Nadu state.
A fire at a crackers factory in the Sivakasi region killed five people and injured four others.
A fire department official confirmed the deaths.
Sivakasi is a known hub for fireworks manufacturing and has seen multiple fire incidents in the past.
No link has been reported between the two fires.
India factory fire kills 39 as Sigachi shuts plant operations: Summary
At least 39 people have died after a fire and explosion at a Sigachi Industries plant in Telangana, India.
The incident occurred on Monday while over 140 people were reportedly inside the facility.
Telangana state officials confirmed that 34 people were injured and 25 of the deceased remain unidentified.
The Telangana government has set up a five-member committee to investigate the cause.
The cause of the fire has not been disclosed by the company.
GV Narayana Rao of the fire disaster response service said the building was destroyed.
Recovery operations are ongoing to clear debris and confirm the final death toll.
Sigachi Industries said it is halting operations at the site for 90 days due to damage.
The company noted that the plant is fully insured and it is filing claims.
The Telangana facility accounts for over a quarter of the company’s total capacity.
Sigachi shares fell by around 8 percent following the incident.
In a separate fire, five people died in Tamil Nadu at a fireworks factory.
That fire occurred in Sivakasi, a major crackers production region.
Authorities have not linked the two incidents.
Fire safety at UK nuclear sites praised in European peer review
UK receives positive fire safety review for nuclear sector
The Office for Nuclear Regulation (ONR) has reported that international experts have commended the United Kingdom’s fire safety arrangements at nuclear sites following a European peer review.
According to the Office for Nuclear Regulation, the assessment was conducted under the European Nuclear Safety Regulators Group’s (ENSREG) second Topical Peer Review (TPR 2), which selected fire safety as the core topic.
Although the UK no longer holds EU membership, it participated voluntarily in the process as an ENSREG observer.
The national assessment report submitted by the UK was reviewed by specialists from other countries and included input from six licensed nuclear operators in Great Britain alongside inspectors from ONR’s Nuclear Internal Hazards and Site Safety specialism.
The report was recognised for enabling a clear and meaningful peer review through transparent self-assessment findings.
Four good practices identified at UK nuclear sites
ENSREG’s reviewers noted four examples of good performance in the UK’s nuclear fire safety approach.
The Office for Nuclear Regulation stated that these included a sector-wide evaluation of combustible cladding risks, initiated to integrate lessons from the Grenfell Tower fire into nuclear facility protocols.
At Sizewell B, a verification step was introduced for hot work safety, requiring checks beyond the standard assessment and review procedures to improve work area safety.
Position monitoring systems were praised at Hinkley Point C, Sizewell B, and other advanced gas-cooled reactors.
These systems raise alerts in control rooms if fire doors forming part of compartment boundaries are left open.
At Sellafield, reviewers highlighted the use of automatic fire suppression systems on tug engines transporting material across the site.
Each example was described by ENSREG as a notable accomplishment that had been implemented effectively.
Areas for improvement acknowledged by ONR
The UK’s self-assessment also identified three areas for development, which were agreed upon by international reviewers.
According to the Office for Nuclear Regulation, one improvement concerns the need for more systematic evaluation of combined and knock-on hazards at Springfields Fuels Limited.
A second area involves enhancing the consistency between day-to-day combustible load management and the safety case for fire loading at the Dounreay Prototype Fast Reactor.
The third is the completion of a comprehensive fire safety strategy programme at Sellafield.
ENSREG noted these points as ongoing actions required for further strengthening the UK’s nuclear fire safety arrangements.
European countries developing response plans to TPR 2
The Office for Nuclear Regulation stated that countries involved in TPR 2 are now preparing national action plans based on the findings and recommendations.
Each participating country is expected to address the areas of improvement identified in their respective reviews.
The UK’s involvement was positioned as an opportunity to align practices with European standards despite not being a member of the EU.
The peer review was structured to support knowledge exchange and reinforce cross-border learning on fire protection in nuclear settings.
ONR highlights UK regulatory approach to fire safety
Diego Lisbona, Head of Profession for Nuclear Internal Hazards and Site Safety at ONR, said: “The publication of the TPR 2 findings culminates efforts from industry and ONR to benchmark UK nuclear fire safety with practices from across Europe.
“We’re pleased that UK approaches have been recognised as areas of good performance.
“The emergence of no new findings from the peer review illustrates the effectiveness of the UK regulatory regime for nuclear fire safety.”
Lisbona added: “The assessment shows that the UK’s fire safety arrangements meet expectations across several key technical areas and reflect good practice in comparison to international counterparts.
“We continue to support collaborative processes like TPR 2 to strengthen oversight and transparency in the sector.”
Fire safety at UK nuclear sites praised in European peer review: Summary
The Office for Nuclear Regulation has confirmed the UK’s participation in ENSREG’s second Topical Peer Review on fire safety.
The UK took part as an observer following its departure from the European Union.
The UK’s national report was prepared by ONR inspectors and six nuclear licensees.
ENSREG reviewers commended four areas of good performance in the UK’s nuclear fire safety arrangements.
Examples included cladding risk reviews, enhanced hot work procedures, position monitoring on fire doors and fire suppression for transport vehicles.
Three areas for improvement identified by the UK were endorsed by reviewers.
These included hazard assessment at Springfields, combustible load management at Dounreay, and completing strategies at Sellafield.
No new findings were raised during the peer review of the UK report.
ENSREG stated that participating countries would now create action plans to address findings.
ONR’s Diego Lisbona welcomed the confirmation of UK good practices and regulatory performance.
Heathrow Airport closure following fire triggers scrutiny of power supply systems
Impact of Heathrow closure questioned after power supply failure
More than 1,300 flights were cancelled on 21 March 2025 after a fire damaged an electrical substation serving Heathrow Airport.
According to AP News, airport executives said the disruption lasted 18 hours and affected over 200,000 passengers, prompting criticism of Heathrow’s planning and operational response.
Heathrow said the incident required “hundreds of critical systems across the airport” to be “safely powered down and then safely and systematically rebooted”.
The International Air Transport Association (IATA) criticised the lack of redundancy in Heathrow’s infrastructure.
Willie Walsh, IATA’s Director General, said: “This is yet another case of Heathrow letting down both travellers and airlines. And that begs some serious questions.”
Power supply resilience under scrutiny
Heathrow’s management and the National Grid have disagreed over whether the airport could have remained operational using other substations.
John Pettigrew, National Grid’s chief executive, said to the Financial Times: “Each substation individually can provide enough power to Heathrow.”
He added: “Losing a substation is a unique event — but there were two others available. So that is a level of resilience.”
In contrast, Heathrow said its response was focused on safety and that operations resumed “as soon as safely and practically possible”.
Transport Secretary Heidi Alexander stated: “It required hundreds of systems to be safely powered down and then safely powered up with extensive testing.”
Police and security response to substation fire
The London Fire Brigade is leading the investigation into the incident.
Police initially treated the case with counterterrorism protocols due to heightened concerns about infrastructure sabotage across Europe.
However, authorities later confirmed there was “no indication of any foul play”.
MI6 has previously warned of sabotage risks linked to Russia.
Gareth Bacon, transport spokesperson for the Conservative Party, said in Parliament: “Malicious actors will undoubtedly have taken note of this weekend’s events.”
Decision-making process at Heathrow faces review
Questions have been raised regarding Heathrow’s internal decision-making during the incident.
Heathrow CEO Thomas Woldbye assigned the airport’s Chief Operating Officer, Javier Echave, to lead the response.
When asked about the leadership decisions, Transport Secretary Alexander said: “I don’t have all the information that they had available when they made the decision.”
She added: “Safety should always be paramount, but, as I say, it was not my decision.”
Government commissions urgent investigation into Heathrow incident
On 22 March 2025, the UK government formally launched an investigation into the Heathrow power outage.
Energy Secretary Ed Miliband commissioned the National Energy System Operator (NESO) to lead the inquiry under powers granted by the Energy Act.
The investigation will examine the causes of the outage and assess the resilience of energy systems supporting critical national infrastructure.
Miliband said: “That is why working with Ofgem, I have today commissioned the National Energy System Operator to carry out an investigation into this specific incident.”
Investigation to examine broader implications for energy security
NESO will work with Ofgem and other stakeholders, including Heathrow Airport, to assess the incident’s technical causes.
NESO Chief Executive Fintan Slye said: “We will now work with all relevant stakeholders to understand the lessons that can be learned to improve future resilience of Great Britain’s energy system.”
The terms of reference for the investigation will be agreed between NESO, Ofgem and the Department for Energy Security and Net Zero.
Initial findings are expected within six weeks.
Ongoing review part of wider UK energy resilience efforts
The Heathrow investigation forms part of the government’s broader “Plan for Change” to strengthen national infrastructure.
This plan includes the Cabinet Office’s resilience review, which is still underway and due to report in spring 2025.
Transport Secretary Alexander said: “Heathrow is a massive airport that uses the energy of a small city, so it’s imperative we identify how this power failure happened and learn from this.”
Akshay Kaul, Director General for Infrastructure at Ofgem, said: “It’s important we now understand how that happened. Households and businesses should be able to have confidence in the resilience of critical national infrastructure.”
Regulatory oversight and enforcement powers
If the investigation identifies breaches of standards or licence obligations, Ofgem has stated it will consider taking enforcement action.
Kaul said: “To the extent the review finds any breaches of standards or licence obligations, we will not hesitate to take action.”
The findings will inform future steps to strengthen energy resilience and emergency response planning.
Further details of the investigation’s scope will be published in the coming days.
Heathrow power outage triggers UK infrastructure review: Summary
On 21 March 2025, a fire damaged one of three electrical substations serving Heathrow Airport.
The incident resulted in the cancellation of more than 1,300 flights and disrupted travel for over 200,000 passengers.
Heathrow said it safely rebooted systems after an 18-hour shutdown.
National Grid stated that the other two substations could supply sufficient power.
IATA criticised Heathrow’s planning and called for a fairer cost allocation.
Police ruled out foul play.
On 22 March, Energy Secretary Ed Miliband commissioned NESO to investigate the outage.
Ofgem and NESO will assess the technical causes and recommend improvements to energy resilience.
NESO’s initial findings are expected within six weeks.
The Cabinet Office’s broader resilience review is ongoing.
Ofgem has stated it will take enforcement action if any licence breaches are identified.
The investigation’s scope and terms will be published in coordination with the Department for Energy Security and Net Zero.
Heathrow power outage: UK government commissions investigation into airport shutdown after substation fire
Power failure at Heathrow Airport sparks government investigation
A fire at a substation supplying power to Heathrow Airport led to major flight cancellations and disruptions on Friday, prompting the UK government to commission an urgent investigation.
The Department for Energy Security and Net Zero said the investigation will be conducted by the National Energy System Operator (NESO).
The review will assess the cause of the fire and examine the resilience of the UK’s energy infrastructure.
Energy Secretary Ed Miliband said the government aimed to understand both the incident and broader risks: “We are determined to properly understand what happened and what lessons need to be learned.”
Thousands of flights disrupted and passengers stranded worldwide
The power failure caused by the fire at the North Hyde substation in Hayes, west London, disrupted around 1,400 flights according to Flightradar24.
Approximately 120 flights were diverted and over 250,000 passengers were affected over the weekend.
On Saturday, Heathrow operated a full schedule with more than 1,300 flights.
However, the airport reported ongoing cancellations and delays.
More than 70 inbound flights and 30 outbound flights were cancelled that day.
Heathrow Airport said: “We have welcomed the Government’s announcement of an investigation into the cause and response to the off-airport power outage and have launched a review, to be chaired by former Transport Secretary Ruth Kelly, of Heathrow’s response.”
Substation and backup systems under scrutiny
The substation affected by the fire was one of three used by Heathrow.
Diesel generators and battery-powered systems were available to support critical functions like runway lighting, but were not sufficient to maintain full operations.
Heathrow CEO Thomas Woldbye told the BBC: “The incident was not created at Heathrow Airport, it was created outside the airport and we had to deal with the consequences.”
John Pettigrew, chief executive of National Grid, stated to the Financial Times that the airport could have accessed the remaining two substations.
“Losing a substation is a unique event — but there were two others available,” he said.
Official responses and resilience reviews underway
The investigation by NESO will report initial findings to Ofgem and the government within six weeks.
Cabinet Office Minister Pat McFadden is also leading a separate national resilience review.
Fintan Slye, NESO’s CEO, said: “We will now work with all relevant stakeholders to understand the lessons that can be learned to improve the future resilience of Great Britain’s energy system.”
Transport Secretary Heidi Alexander stated: “Heathrow is a massive airport that uses the energy of a small city, so it’s imperative we identify how this power failure happened and learn from this to ensure a vital piece of national infrastructure remains strong.”
Heathrow power outage: UK government to investigate airport shutdown after substation fire: Summary
On Friday 21 March 2025, a fire at the North Hyde electricity substation in west London caused a major power failure affecting Heathrow Airport.
The outage led to nearly 1,400 disrupted flights and stranded thousands of passengers worldwide.
The Department for Energy Security and Net Zero commissioned the National Energy System Operator (NESO) to conduct an investigation.
Initial findings are expected in six weeks.
Energy Secretary Ed Miliband said the government aims to identify any wider lessons on energy resilience for critical infrastructure.
More than 63,000 homes and around 150 people in nearby properties were also affected by the outage.
The Metropolitan Police said counter-terrorism officers were leading initial enquiries but were not treating the incident as suspicious.
Heathrow Airport announced a separate review chaired by former Transport Secretary Ruth Kelly.
NESO, launched in October 2023, manages electricity and gas network planning in Great Britain.
Ofgem stated it would take action if any licence obligations were breached.
Electrical substation fire in London causes widespread outages and Heathrow closure
Fire in Hayes leads to major power outage and airport disruption
A fire at an electrical substation in Hayes, West London has caused a large-scale power outage and led to the closure of Heathrow Airport for the entire day.
The London Fire Brigade responded to the incident late on Thursday night.
Around 70 firefighters and 10 fire engines were deployed to the site on Nestles Avenue, where a transformer had caught fire.
The blaze disrupted the electricity supply to thousands of homes and affected key infrastructure, including Heathrow Airport, which remains closed.
Airport operations suspended due to loss of power
Heathrow Airport, one of the busiest in the world, suspended operations until 23:59 on Friday 21 March 2025.
According to airport officials, more than 1,300 flights scheduled to arrive or depart have been affected.
Passengers were advised not to travel to the airport under any circumstances.
Flight tracking service Flightradar24 reported that 1,351 flights could be cancelled.
Some inbound international flights were diverted to other airports, including Gatwick, Paris and Shannon.
Response from emergency services and government
The London Fire Brigade confirmed that the fire was under control by 06:28 on Friday morning.
Assistant Commissioner Pat Goulbourne said: “This was a very visible and significant incident, and our firefighters worked tirelessly in challenging conditions to bring the fire under control as swiftly as possible.
“Thanks to their efforts and coordinated multi-agency response, we successfully contained the fire and prevented further spread.”
He added: “Due to the significant smoke, we strongly advise local residents to keep their windows and doors closed, as some smoke will remain for a number of hours today.
“Scientific advisors will also be on-site this morning to conduct further assessments and monitor the air quality.”
Energy Secretary Ed Miliband said in media interviews that National Grid was responding to what he described as an “unprecedented event”.
He added: “It appears to have knocked out a back-up generator as well as a substation itself.”
Local impact and power restoration efforts
Power cuts affected more than 16,000 homes, according to Scottish and Southern Electricity Networks.
By 06:00 GMT, National Grid reported that electricity had been restored to 62,000 customers, with 4,900 still without power.
Residents in the area reported watching the flames overnight.
Around 150 people were evacuated, and firefighters led 29 people to safety from neighbouring buildings.
A 200-metre cordon was set up as a precaution. The fire brigade’s Control Officers handled over 200 emergency calls.
Investigation into cause of fire underway
Fire investigators are working with the Metropolitan Police Service to determine the cause of the fire.
Emergency services were initially called to the scene at 23:23 on Thursday.
Crews from Hayes, Heathrow, Hillingdon, Southall and surrounding stations were mobilised.
The cause of the fire remains unknown at this stage.
The fire brigade has confirmed that teams will maintain a presence at the site to support the National Grid’s assessment work.
Electrical substation fire in London causes widespread outages and Heathrow closure: Summary
A fire broke out at an electrical substation on Nestles Avenue in Hayes, West London at 23:23 on Thursday 20 March 2025.
The fire involved a transformer and led to a major power outage across the region.
London Fire Brigade deployed 10 engines and approximately 70 firefighters.
The fire was declared under control by 06:28 on Friday.
Heathrow Airport closed all operations for the day as a result of the outage, with over 1,300 flights affected.
Power supply was disrupted to more than 16,000 properties.
At least 150 people were evacuated, including 29 who were led to safety by firefighters.
A 200-metre cordon was established.
The government confirmed that a back-up generator was also impacted.
Fire investigators are working with the Metropolitan Police to identify the cause.
National Grid has restored power to most affected properties but some remain without supply.
Emergency crews and scientific advisors remain at the scene.
11 Most Common Flammable Gasses
Flammable gases are an integral part of our everyday lives.
From household uses like cooking and heating to industrial applications, these gases are both useful and potentially dangerous.
If not handled properly, flammable gases can lead to fires, explosions, or health hazards.
This article will explore what flammable gases are, introduce 11 common examples, and provide essential safety tips for handling them.
What are Flammable Gasses?
Flammable gases are substances that can easily ignite and burn when mixed with air and exposed to an ignition source.
These gases typically have a low flashpoint, meaning they ignite at relatively low temperatures, making them highly dangerous in certain conditions.
Flammable gases are used in many industries and everyday applications.
Common examples include cooking fuel, industrial processes, chemical production, and energy generation.
While they are incredibly useful, improper handling can lead to fires, explosions, or toxic exposure.
A flammable gas becomes hazardous when its concentration in the air reaches its flammability limits, creating an environment ripe for ignition.
These limits are the lower explosive limit (LEL) and the upper explosive limit (UEL).
Outside these ranges, the gas may not ignite, but within them, a spark or flame can cause severe damage.
11 Most Common Flammable Gasses
Acetylene
Acetylene is a hydrocarbon gas used primarily in the welding and cutting industry.
Composed of carbon and hydrogen, this gas is known for its ability to produce an extremely high-temperature flame.
It plays a vital role in the metalworking industry for processes like oxyacetylene welding and cutting.
Additionally, acetylene is a critical raw material in the production of certain plastics and chemicals.
However, acetylene is highly unstable and flammable.
It can ignite at very low temperatures and is prone to explosive reactions when stored or handled improperly, particularly under high pressure.
Ammonia
Ammonia is a pungent gas widely used in agriculture and refrigeration.
It is crucial in the production of fertilisers, helping boost crop yields.
Ammonia also serves as a refrigerant in industrial cooling systems and is a component in certain cleaning agents.
Although it is not as flammable as some other gases on this list, it can ignite under specific conditions, particularly in the presence of high heat.
Ammonia is also highly toxic, and exposure can lead to respiratory distress, skin irritation, and even death at high concentrations.
Butane
Butane is a highly flammable gas that is colorless and odourless in its natural state.
It is widely used as a fuel in lighters and portable stoves and as a propellant in aerosol sprays.
Butane is also a common component in liquefied petroleum gas (LPG), used for heating and cooking.
The dangers of butane lie in its ability to ignite easily, even with minimal exposure to a spark or flame.
In confined spaces, butane can accumulate and cause explosive reactions.
Its high flammability requires careful storage and handling to prevent accidents.
Carbon Monoxide
Carbon monoxide is a flammable and highly toxic gas that is colorless, odourless, and tasteless.
It is produced by incomplete combustion of carbon-containing fuels such as wood, coal, and gasoline.
Carbon monoxide is used in industrial processes, including the production of certain chemicals and fuels.
Its dangers, however, are immense.
Inhalation of carbon monoxide can result in poisoning, as it binds to hemoglobin in the blood, reducing oxygen delivery to vital organs.
Additionally, its flammability makes it a fire and explosion hazard, especially in poorly ventilated spaces.
Ethane
Ethane is a colorless and odorless hydrocarbon gas that serves as a vital component in the petrochemical industry.
It is used primarily as a feedstock for ethylene production, which in turn is used to manufacture plastics, antifreeze, and other chemicals.
Ethane is also found in natural gas and is used as a fuel for heating.
The primary risk associated with ethane is its high flammability.
It forms explosive mixtures with air and requires careful storage and monitoring to prevent leaks that could lead to fires or explosions.
Ethylene
Ethylene is another hydrocarbon gas that plays a significant role in agriculture and industry.
It is used as a plant hormone to accelerate the ripening of fruits and as a feedstock for producing polyethylene, the most common plastic.
Ethylene is also used in the automotive industry for antifreeze production.
Despite its widespread use, ethylene is highly flammable and can ignite easily.
In industrial settings, it poses a risk of fire and explosion, particularly in enclosed spaces without adequate ventilation.
Hydrogen
Hydrogen is the lightest and most abundant element in the universe.
It is a versatile gas used in various industries, including energy production, chemical manufacturing, and aerospace.
Hydrogen is a key component in fuel cells, which produce clean energy, and is also used in refining petroleum and producing ammonia.
However, hydrogen’s flammability and small molecular size make it highly dangerous.
It burns with an invisible flame, making fires difficult to detect, and is prone to leaks, which can lead to explosions in confined areas.
Hydrogen Sulfide
Hydrogen sulfide is a flammable and highly toxic gas with a distinct smell of rotten eggs.
It is commonly found in crude oil, natural gas, and sewage systems.
Hydrogen sulfide is used in the production of sulfuric acid and other chemicals.
Despite its usefulness, this gas is extremely hazardous.
It can cause respiratory failure and death at high concentrations and is flammable, forming explosive mixtures with air.
Proper monitoring and ventilation are essential to ensure safety when working with hydrogen sulfide.
Methane
Methane is the primary component of natural gas and one of the most abundant flammable gases on Earth.
It is used as a fuel for heating, electricity generation, and as a feedstock for producing hydrogen and other chemicals.
Methane is also a significant contributor to greenhouse gas emissions when released into the atmosphere.
The dangers of methane lie in its flammability and potential to cause explosions.
It is odourless in its natural state, making gas detectors crucial for leak detection.
Propane
Propane is a widely used fuel in residential, commercial, and industrial settings.
It is a component of LPG and is used for heating, cooking, and powering vehicles.
Propane is stored as a liquid under pressure and vaporizes when released, making it easy to transport and use.
However, propane is highly flammable and can cause explosions if leaks occur in confined spaces.
Its use requires proper storage, regular inspections, and adherence to safety guidelines.
Silane
Silane is a silicon-based gas used primarily in the electronics and renewable energy industries.
It is essential in the production of semiconductors, solar panels, and silicon-based materials.
Silane is highly reactive and ignites spontaneously upon contact with air, making it one of the most dangerous gases on this list.
Its handling requires specialized storage and strict safety protocols to prevent accidental ignition or explosions.
How to Stay Safe Around Flammable Gasses
Flammable gases can pose serious risks if not handled correctly.
Proper safety measures are crucial to prevent fires, explosions, and exposure-related hazards.
Store Gases Safely
Always store flammable gases in approved, clearly labeled containers.
Keep them in well-ventilated areas, away from heat sources, sparks, or open flames.
Ensure storage areas are cool and dry to prevent leaks or pressure buildup.
Leak Detection
Regularly inspect gas containers, pipelines, and connections for leaks.
Gas detectors are highly recommended in storage or usage areas to identify leaks early.
Fire detection systems should also be used in case due to their flammability.
Maintain Proper Ventilation
Work with flammable gases in areas with good airflow.
Ventilation helps disperse gas buildup, reducing the risk of accidental ignition.
Avoid Ignition Sources
Keep flammable gases away from open flames, smoking, electrical equipment, and other potential ignition sources.
Follow Manufacturer Guidelines
Always follow the safety instructions provided for storing and using specific gases.
Wear Protective Gear
Use appropriate personal protective equipment (PPE), such as gloves, goggles, and flame-resistant clothing, when handling flammable gases.
Provide Training
Ensure all workers handling gases are trained in safety protocols and emergency response procedures.
Conclusion
You should now have an understanding of 11 of the most common flammable gasses.
Flammable gases are essential in various applications but pose significant risks if mishandled.
Understanding their characteristics and following safety guidelines can reduce the risk of accidents and create a safer environment.
Stay informed, stay vigilant, and always prioritize safety when working with flammable gases.