HSG140 is HSE guidance for controlling fire and explosion risks when flammable liquids are used or handled at work. It covers general work activities, small-scale chemical processing and spraying, including liquid transfer, ventilation, ignition control, static electricity and hazardous areas. HSG140 supports compliance with DSEAR but does not replace the employer’s site-specific fire and explosion risk assessment.
HSG140, Safe use and handling of flammable liquids, is guidance published by the Health and Safety Executive for people responsible for using and handling flammable liquids at work.
The current publication is the second edition, published in 2015.
It is intended for activities including:
The guidance explains the fire and explosion hazards associated with flammable liquids and practical measures that can be used to control those risks.
No. HSG140 is HSE guidance rather than a separate piece of legislation.
The main Great Britain workplace legislation governing fire and explosion risks from dangerous substances is the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR).
HSG140 provides practical guidance for applying DSEAR principles to the use and handling of flammable liquids.
See our DSEAR Regulations 2002 guide for further information on the underlying legal duties.
Flammable liquids are liquids capable of producing vapour that can ignite when mixed with air.
Under current classification principles, a flammable liquid generally has a flashpoint of 60°C or below.
However, liquids with higher flashpoints may still create a fire or explosion risk where they are heated to temperatures at or above their flashpoint.
The actual conditions under which a liquid is stored, transferred, processed or sprayed should therefore be considered when assessing the risk.
Flashpoint is the minimum temperature, under specified test conditions, at which a liquid gives off enough vapour to ignite momentarily when an ignition source is applied.
The lower the flashpoint, the more readily a liquid can normally generate ignitable vapour under typical workplace conditions.
Flashpoint is an important factor in a DSEAR assessment, but it should not be considered on its own.
Other relevant properties can include:
Before flammable liquids are used or handled, employers should assess the circumstances in which a fire or explosion could occur and the potential consequences.
Relevant considerations include:
The assessment should consider normal operation as well as foreseeable failures, maintenance activities and abnormal conditions.
Where reasonably practicable, one of the first options should be to eliminate the flammable liquid or replace it with a substance or process presenting a lower fire and explosion risk.
Possible approaches can include:
Substitution should consider the overall health and safety implications rather than simply replacing one hazard with another.
The quantity of flammable liquid present within a work area should be kept to the minimum reasonably required for the activity being carried out.
Bulk stocks and containers not needed for current operations should normally be kept in an appropriate storage area rather than accumulating within the process area.
HSE provides more detailed guidance on the storage of flammable liquids in containers in HSG51.
See our HSG51 flammable-liquid storage guide.
Transfer operations should be designed to minimise releases of liquid and vapour and reduce the likelihood of ignition.
Where possible, closed transfer systems can provide better control than manually pouring flammable liquids between open containers.
Depending on the process, precautions may include:
Transfer equipment should be compatible with the liquid and suitable for the conditions in which it will be used.
The movement of flammable liquids can generate static electricity. Splash filling and excessive free fall can increase electrostatic charging and also increase vapour generation.
HSG140 therefore advises designing plant and procedures to minimise splash filling and unnecessary free fall during filling and transfer operations.
Where practicable, filling arrangements should allow liquid to enter a container or vessel in a controlled manner.
Static electricity can accumulate during activities such as pumping, filtering, filling, emptying and spraying flammable liquids.
If the accumulated charge discharges as a sufficiently energetic spark within a flammable atmosphere, ignition can occur.
Static hazards may also arise from:
Static electricity should therefore be considered wherever flammable vapours may be present.
Conductive equipment used for handling flammable liquids should be appropriately bonded and earthed where necessary to prevent dangerous electrostatic charge accumulating.
Controls can include:
HSG140 advises that earth continuity should be checked regularly and that the complete transfer system should be considered, including valves, hoses, fittings and other conductive components.
Ventilation should prevent flammable vapour accumulating to dangerous concentrations.
The ventilation required depends on matters including:
Natural ventilation may be sufficient for some activities, while local exhaust or mechanical ventilation may be needed where vapour generation is greater or natural air movement cannot provide adequate control.
Many common solvent vapours are heavier than air and can travel along floors or accumulate in low areas away from the point where the liquid was released.
Particular attention should therefore be given to:
A vapour release can therefore create a hazardous area some distance from the original source if suitable ventilation and containment are not provided.
Potential ignition sources should be eliminated or suitably controlled wherever a flammable atmosphere could occur.
Examples include:
Equipment within a classified hazardous area must be suitable for the zone and explosive atmosphere involved.
Where an explosive atmosphere may occur in quantities requiring special precautions, DSEAR requires the relevant areas to be identified and classified.
Hazardous-area classification should consider:
The resulting classification determines the precautions and equipment requirements applying within the hazardous area.
See our DSEAR guide for more information on Zones 0, 1 and 2.
Normal electrical equipment should not be used within an area classified as hazardous unless it is suitable for the applicable explosive atmosphere and zone.
Electrical equipment can provide ignition through sparks, arcs or hot surfaces.
HSG140 also advises controlling unauthorised equipment within hazardous areas. Items not suitable for the zone should not be introduced simply because they are portable or battery powered.
The required equipment specification should be based on the hazardous-area classification.
Dispensing and decanting can create additional risk because containers are opened and liquid and vapour may be released directly into the workplace.
Controls may include:
Containers used for transferred liquids should also remain correctly identified and labelled.
Dedicated storage areas should primarily be used for storage rather than routine operations likely to release flammable vapour.
Activities such as dispensing, mixing and repacking can increase the likelihood of spills and vapour release and may require a separately designed work area.
HSG51 provides specific guidance on storage, while HSG140 addresses the risks arising once flammable liquids are being used and handled.
Mixing processes should be assessed for both the normal release of flammable vapour and foreseeable failures such as spills, overfilling, equipment failure or loss of ventilation.
Depending on the process, controls may include:
Chemical reaction hazards should also be assessed where substances are being combined rather than simply physically mixed.
Spraying can create flammable mists and vapours over a much larger area than ordinary liquid handling and therefore requires particularly careful control.
Where practicable, spraying should take place within a suitably designed spray booth or enclosure with effective ventilation.
Important controls can include:
Health risks from solvent exposure must also be assessed separately under COSHH.
HSG140 advises that ventilation for relevant spraying operations should maintain flammable vapour concentrations below 25% of the Lower Explosion Limit (LEL) during spraying and subsequent drying.
The actual controls required depend on the substance, equipment, workplace and spraying process.
Monitoring may be necessary in some circumstances to demonstrate that safe concentrations are being maintained.
COSHH controls may require significantly lower airborne concentrations where the solvent also presents a health hazard.
Sometimes the size or nature of the item being coated makes use of a conventional spray booth impracticable.
Where spraying takes place within a workroom or open work area, additional precautions are required.
These may include:
Outdoor spraying should also consider wind direction, nearby building openings and locations where vapours could collect.
Spraying flammable liquids in confined spaces presents particularly serious fire, explosion and health risks because dangerous vapour concentrations can develop very quickly.
HSG140 advises that confined-space spraying requires stringent controls, including suitable mechanical exhaust ventilation and formal safe-working arrangements.
Entry into a confined space should be controlled in accordance with the Confined Spaces Regulations and associated HSE guidance.
Specialist competent advice may be required before this type of work is undertaken.
Maintenance can introduce ignition sources into areas where flammable liquids or residual vapours may be present.
Activities such as:
should be assessed before work begins.
Where appropriate, a permit-to-work system should be used to ensure equipment has been isolated, drained, cleaned, ventilated or otherwise made safe before ignition-producing work is carried out.
Spill procedures should be established before an incident occurs and should reflect the quantity, volatility and hazards of the liquids involved.
Depending on the circumstances, actions may include:
Workers expected to respond to spills should receive suitable information and training.
HSG140 principally addresses fire and explosion risks, but many flammable liquids also present significant health hazards.
A solvent may therefore require controls under both:
For example, ventilation designed only to prevent an explosive atmosphere may not necessarily reduce employee exposure sufficiently to satisfy COSHH.
See our COSHH Regulations 2002 guide.
HSG140 is one of three principal HSE publications dealing with fire and explosion risks from flammable liquids:
A site may therefore need more than one of these publications.
For example, a facility may use HSG51 for drum storage, HSG140 for dispensing and process use, and HSG176 for a separate bulk tank installation.
Chemstore provides storage solutions that can help separate bulk flammable-liquid inventories from working areas and support the controls identified through a site’s DSEAR risk assessment.
For larger drum and IBC inventories, the Firevault range provides dedicated fire-rated flammable-liquid storage, with options for features such as ventilation, static management and specialist equipment where required.
For smaller indoor quantities, Chemstore supplies flammable-liquid safety cabinets, including BS EN 14470-1 fire-rated options.
Storage equipment should be selected according to the substances, quantities, process activities, fire and explosion risks and findings of the DSEAR assessment.
A Chemstore product does not replace safe operating procedures, process controls or the employer’s duties under DSEAR.
The Health and Safety Executive provides the current HSG140 guidance directly on its website.
This page summarises HSG140 and provides general information only. It does not replace the HSE publication, DSEAR, COSHH, Safety Data Sheets, a hazardous-area classification, a site-specific risk assessment or advice from a competent person.
The controls required for an individual workplace should always be determined from the flammable liquids, quantities, process temperatures, transfer methods, ventilation, possible release scenarios and ignition risks involved.
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