What is L138?
L138 is the HSE's Approved Code of Practice (ACOP) and guidance for the Dangerous Substances and Explosive Atmospheres Regulations 2002, known as DSEAR. It provides practical guidance on protecting workers and others from fire and explosion risks caused by dangerous substances in the workplace.
DSEAR applies wherever dangerous substances are present that could create a risk of fire, explosion, or similar energetic event. This includes:
- Petrol, diesel, and other flammable liquids
- LPG and other flammable gases
- Flammable dusts (wood, flour, sugar, metal powders, coal)
- Flammable vapours and mists
- Substances that can react dangerously together
- Explosive substances and articles
The Regulations work alongside ATEX (the Equipment and Protective Systems Intended for Use in Potentially Explosive Atmospheres Regulations) to create a comprehensive framework for explosion protection.
Who Needs This Document?
L138 is essential for:
- Petrol stations and fuel distributors handling flammable liquids
- Manufacturing companies using solvents, paints, or flammable materials
- Food and drink producers with combustible dust risks
- Wood and timber industries generating wood dust
- Chemical and pharmaceutical companies handling flammable substances
- Spray painting operations creating flammable vapour atmospheres
- Printing companies using flammable inks and solvents
- Warehouses storing dangerous substances
- Agricultural businesses storing grain and other dusty materials
- Any workplace with boiler rooms, LPG storage, or similar
Key Topics Covered
Risk Assessment
L138 requires a specific dangerous substances risk assessment covering:
- Identifying dangerous substances present
- Identifying activities involving dangerous substances
- Evaluating the potential for explosive atmospheres to occur
- Identifying possible ignition sources
- Evaluating the likely consequences of fire or explosion
- Identifying who might be harmed
Elimination and Reduction
The hierarchy of controls for dangerous substances:
- Eliminate the dangerous substance if possible (substitute with non-flammable alternative)
- Reduce the quantity of dangerous substance to the minimum needed
- Prevent the release of dangerous substances (containment, ventilation)
- Control releases at source (extraction, dilution ventilation)
- Prevent formation of explosive atmospheres
- Avoid ignition sources in hazardous areas
- Mitigate the effects of any fire or explosion
Hazardous Area Classification
L138 explains how to classify areas where explosive atmospheres may occur:
| Zone | Description | Example |
|---|---|---|
| Zone 0 | Explosive atmosphere continuously or for long periods | Inside tanks, vessels |
| Zone 1 | Explosive atmosphere likely to occur occasionally | Near filling points, vents |
| Zone 2 | Explosive atmosphere not likely, but may occur briefly | Around storage areas |
| Zone 20 | Combustible dust cloud continuously or frequently | Inside dust extraction systems |
| Zone 21 | Combustible dust cloud likely occasionally | Near bag filling, transfer points |
| Zone 22 | Combustible dust cloud not likely, but may occur briefly | Around dusty process areas |
Equipment in Hazardous Areas
Equipment used in classified zones must be suitable:
- ATEX-certified equipment for the zone classification
- Appropriate temperature class (T-rating) for substances present
- Correct gas group for the gases/vapours present
- Proper maintenance to retain explosion protection
Ignition Source Control
L138 identifies potential ignition sources to control:
- Electrical equipment and wiring
- Static electricity
- Hot surfaces
- Flames and hot gases
- Mechanical sparks
- Chemical reactions
- Electromagnetic radiation
- Lightning
Emergency Procedures
Requirements for emergency arrangements:
- Warning and communication systems
- Escape routes and assembly points
- Fire fighting and explosion suppression equipment
- Safe shutdown procedures
- Information for emergency services
- Recovery procedures
Explosion Protection Document
DSEAR requires an Explosion Protection Document where a risk assessment identifies a risk from dangerous substances. This must include:
- The hazards and risks identified
- The control measures in place
- The areas classified as hazardous zones
- Arrangements for safe use of work equipment
- Verification of safety by a competent person
Legal Status
L138 is an Approved Code of Practice. Following its guidance provides a clear route to DSEAR compliance. Failure to follow the ACOP can be used as evidence in court that the Regulations have been breached, unless you can demonstrate compliance through alternative means.
Why It Matters
Fire and explosion incidents can be catastrophic:
The Risks
- Explosions can destroy buildings and kill multiple people
- Flash fires cause severe burns and fatalities
- Dust explosions have killed workers in flour mills, sawmills, and factories
- Secondary explosions often follow initial events as dust is disturbed
Major Incidents
Workplace explosions have resulted in:
- Multiple fatalities in a single incident
- Complete destruction of buildings and plant
- Fires spreading to neighbouring properties
- Environmental contamination
- Business closure and criminal prosecution
The Consequences
- Multiple fatalities in serious explosions
- Corporate manslaughter charges for gross negligence
- Unlimited fines for DSEAR breaches
- Destruction of property and business
- Environmental prosecution for contamination
Prevention
L138 provides the framework to prevent explosions by:
- Identifying where explosive atmospheres can form
- Eliminating or controlling dangerous substances
- Classifying hazardous areas and selecting appropriate equipment
- Controlling ignition sources
- Having emergency procedures in place
Common DSEAR Situations
Petrol Stations
Petrol vapour creates explosive atmospheres around pumps and underground tanks. Zone classification, intrinsically safe equipment, and static discharge precautions are essential.
Spray Painting
Solvent vapours from paints and coatings create explosive atmospheres in spray booths. Proper ventilation, zone classification, and ATEX equipment are required.
Wood and Furniture Manufacturing
Wood dust is highly explosive. Extraction systems, housekeeping to prevent dust accumulation, and proper zone classification protect against dust explosions.
Food Manufacturing
Flour, sugar, starch, and other food dusts can explode. Grain silos and milling operations have historically suffered major dust explosions.
Vehicle Workshops
Petrol vapour, battery charging hydrogen, and LPG from vehicles can create explosive atmospheres. Proper ventilation and ignition source control are needed.
Quick Compliance Checklist
| Step | Action |
|---|---|
| 1 | Identify all dangerous substances in your workplace |
| 2 | Carry out a DSEAR risk assessment |
| 3 | Classify areas where explosive atmospheres may occur |
| 4 | Ensure equipment in hazardous areas is suitable |
| 5 | Control ignition sources |
| 6 | Prepare an Explosion Protection Document |
| 7 | Train workers on the risks and precautions |
| 8 | Review when circumstances change |
Further Resources
- DSEAR Regulations 2002 (legislation.gov.uk)
- HSE DSEAR web pages
- HSE guidance on dust explosion hazards
This page summarises the ACOP L138. For full legal compliance, obtain and read the complete document from HSE. This summary is not a substitute for professional advice or the full ACOP text.