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Fire Prevention Is Our Intention: A Guide to Storing Hazardous Materials Safely

Fire Prevention Is Our Intention: A Guide to Storing Hazardous Materials Safely

Flammable hazardous materials show up more often than people expect: construction sites, factories, laboratories, educational sites. Getting storage wrong isn't just a compliance box left unticked, it's a genuine fire risk with serious consequences.

What actually causes a fire

Every fire needs three things at once: fuel, heat, and oxygen. This is the "fire triangle." Remove any one of the three and a fire either can't start or will go out.

Fire triangle - Wikipedia
  • Fuel is the flammable or combustible material itself, liquid, gas, or solid.
  • Heat is the ignition source: an open flame, a spark, or a chemical reaction.
  • Oxygen usually comes from the air, but can also come from chemical oxidisers.

Storage strategy is really just controlling these three factors so they never combine.

What counts as a hazardous material

Under DSEAR (the Dangerous Substances and Explosive Atmospheres Regulations), hazardous materials aren't limited to the obvious ones. The definition covers:

  • Flammable, highly flammable, or extremely flammable liquids, gases, oxidisers, or explosive materials
  • Any substance whose properties, use, or presence in the workplace creates a risk
  • Combustible dusts, including organic, synthetic, or natural materials capable of forming an explosive mixture
  • Substances corrosive to metals, such as hydrochloric or sulphuric acid, which can generate hydrogen gas even though they're not flammable themselves
  • Pressurised gas systems, not just commercial cylinders

The legislation behind it

The key pieces of UK guidance and law to know:

  • DSEAR 2002 requires employers to take all reasonable precautions to eliminate danger from flammable liquids at the source, substituting safer materials where possible.
  • The Health and Safety at Work Act 1974 is the primary legislation covering occupational safety in Great Britain.
  • HSG51 covers the storage of flammable liquids in containers, aimed at anyone responsible for dangerous substance storage regardless of facility size.
  • HSG71 focuses on classification and segregation of incompatible hazardous materials.
  • HSG140 covers safe use and handling of flammable liquids in general work activities.
  • COSHH (Control of Substances Hazardous to Health) sits alongside these.
  • BS EN 14470 Parts 1 and 2 set performance requirements for fire safety cabinets storing flammable liquids and pressurised gas cylinders respectively.

HSG71 Chart

Storing flammable liquids indoors

Fire-resisting storerooms and workrooms need a minimum of 30 minutes fire resistance for integrity, insulation, and load-bearing capacity. That rises to 60 minutes where the space adjoins residential accommodation.

Storage cabinets and bins need the same 30-minute minimum, built to specific principles: no gaps or openings in joints, close-fitting doors, and fastenings with a melting point above 750°C. Recommended maximum quantities for cabinet storage are 50 litres for extremely or highly flammable liquids (or any flammable liquid with a flashpoint below the workroom's maximum ambient temperature), and 250 litres for other flammable liquids with a flashpoint up to 60°C. These are recommended maxima, not absolute limits, but storing beyond them needs a documented justification.

Storing flammable liquids outdoors

For larger volumes, typically held in 200L drums or 1000L IBCs, moving storage outside and away from the workplace is one of the most effective controls available. Minimum separation distances from site boundaries, occupied buildings, and process areas scale with volume:

Quantity Stored (L) Minimum Separation Distance (M)
Up to 1,000 2
1,000 to 100,000 4
Above 100,000 7.5

 

Where these distances can't be achieved, additional protective measures can justify a reduction: fire-rated construction (60 minutes minimum, with enhanced units offering 90 or 120 minutes), legally compliant bunding to contain leaks and spills, fire-rated doors with intumescent seals, proper ventilation, temperature control, and explosion relief panels.

Segregating incompatible materials

Not all hazardous substances can be stored together safely. HSG71 sets out a segregation table covering explosives, compressed gases, flammable liquids and solids, oxidising substances, toxic substances, and corrosives. Depending on the combination, materials may need to be kept apart, segregated into separate compartments, or fully isolated, organic peroxides, for example, are generally recommended for dedicated buildings or secure fire-resisting cabinets, kept well away from anything else.

Safety Data Sheets are your first port of call

SDS documents are the best source of information on compatibility between materials, and they need to be accessible to all staff at all times, not filed away somewhere no one checks. They're essential for understanding toxicity, safe co-location, accidental release procedures, firefighting measures, and first aid.

Three practical ways to prevent a fire

  1. Limit quantities on-site. Keep only what you need, working within the recommended cabinet maxima wherever possible.
  2. Provide proper ventilation. Flammable vapours need to be dispersed, not allowed to accumulate, whether through natural airflow or mechanical ventilation.
  3. Control ignition sources. Ground and bond equipment, ban smoking in storage and handling areas, keep flammables away from hot equipment or open flames, and use intrinsically safe, non-sparking tools.

Questions worth asking yourself

  • Is there genuinely good airflow where flammable substances are stored and used?
  • Have all realistic ignition sources actually been removed, not just the obvious ones?
  • Are your substances in the right type of storage unit, at the right distance from occupied buildings and ignition sources?
  • Would a spill actually be contained, or would it spread beyond the storage unit?
  • Could a less flammable alternative do the same job?

Why it matters

Getting hazardous material storage wrong isn't a paperwork failure, it's a genuine safety risk to people and property. The regulations exist because fires involving flammable substances escalate fast, and the margin for getting containment and separation right is small.


References

This guidance is based on material produced by the BSIF's Spills Containment and Control Group.