Storing flammable liquids: Key considerations

When considering the storage of flammable liquids, alongside all the normal measures associated with storing liquids there are strict rules concerning separation distances. This is the distance the flammable liquids must be stored from occupied buildings, boundaries, process units, flammable liquid storage tanks and or sources of ignition.

If you can achieve the relevant distance you can use a non-fire rated “standard” storage unit to house your flammable liquids. If on the other hand you can’t achieve the relevant distance the storage unit will need to be constructed to provide the contents with fire protection to ensure they don’t contribute to a fire. In the UK the minimum standard of fire resistance for the storage unit is 30 minutes but more typically units with a resistance of 60, 90 or 120 minutes are the norm.

In the UK we are bound by The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) which places duties on employers and the self-employed (considered employers for the purposes of the Regulations) to assess and eliminate or reduce risks from dangerous substances so far as is reasonably practicable.

Supporting documentation that you should also reference:

DSEAR 2002: Approved Code of Practice and Guidance

DSEAR 2002: A Brief Guide to the Regulations

HSG51 – Storage of Flammable Liquids in Containers

HSG71 – Chemical Warehousing

HSG140 – Safe use and Handling of Flammable Liquids

It is imperative that you fully understand the hazards associated with all the products you store and use. Information from Safety Data Sheets and manufacturer’s help desks are invaluable sources of accurate information and manufactures of safety equipment such as fire rated storage units, earthing wires, and or flammable liquid transfer containers will be more than happy to offer specific advice too. Please don’t forget to consult with your local authority fire brigade and your insurance provider.
 
Some questions worth considering when working with flammable substances:

Is there good natural air movement in and around where the flammable substances are stored and used?

If not you may have to consider mechanical air changes. Good ventilation will mean that any vapours given off from a spill, leak, or release will be rapidly dispersed.
 
Have all the obvious ignition sources been removed from the storage and handling areas?

You need to think outside the box as an ignition source can be very varied, sparks from electrical equipment, welding or cutting tools, hot surfaces, open flames, static charge etc. An explosion can even be caused by the simple action of decanting a flammable liquid from one container to another if they have not been earthed.
 
Are your flammable substances kept in the correct type of container?

Does it need to be fire rated?

If there is a spill will it be contained and prevented from spreading?

Dependant on the quantity of product involved and the separation distance you may need a fire rated storage unit.
 
Can you replace a flammable substance for a less flammable one or can you eliminate it from the process completely?

Processes and products evolve, check with your supplier(s) and see if they can help you redesign yours to make it safer.
 
Are your flammable substances stored and used in a different area to other processes?

By separating them you will lessen the risk of an incident and improve workplace safety.

For practical purposes where flammable liquids are required in a process, there is likely to be a need for a limited quantity to be stored and available in the workplace. It is the responsibility of the employer/duty holder when carrying out their risk assessment to justify the need to store any particular quantity of flammable liquid within the work room/working area.

However, the guiding principle is that only the minimum quantity needed for frequently occurring activities or an amount required for use during half a day or one shift should be present in the work room/working area. Actual quantities will depend on the work activity and also the arrangements for controlling the fire risks. When not in use, containers of flammable liquids needed for ongoing work should be kept closed and stored in suitable fire resistant cabinets or bins which are also designed to retain spills. They should be located in designated areas that are where possible away from the processing area don’t interfere with any escape route from the working area.

Flammable liquids should be stored separately from other dangerous substances that may enhance the risk of fire or compromise the integrity of the container or cabinet/bin it’s stored in; for example, oxidizers and corrosive materials should be stored separately from each other. Remember other dangerous substances may also be flammable in their own right however, it is still inappropriate to store these in the same cabinet/bin with flammable liquids.

The HSE recommends that the maximum quantities that are stored in cabinets/bins are no more than 50ltr for extremely flammable, highly flammable and those flammable liquids with a flashpoint below the maximum ambient temperature 30ºC of the working area; and no more than 250ltr for other flammable liquids with a higher flashpoint of up to 55°C. These quantities are intended to be viewed as recommended maximums and represent good industry safe practice, rather than being taken as the absolute limits. There can be some flexibility with the limits of the quantities stored, where it is understood that the design of the building and or the pattern of work can sometimes make adherence to these quantities difficult. For example in large or open-plan working areas where the employer/duty holder does identify a need to store quantities in excess of the recommended maximum, they must fully demonstrate the need for this requirement and in particular the risk assessment should take into account:

The properties of the materials to be stored or handled (For mixed storage the worst case situation should be applied, i.e. all materials in the storage cabinets or bin should be considered as being as dangerous as the one that has the lowest flashpoint) the size of the workroom/working area and the number of people working in it. The amount of flammable liquids being handled in the working area and the quantities of liquid that may be accidentally released or spilled.

In the event of an incident the objective is to ensure that people can safely escape from the working area and in this context, the purpose of storing flammable substances in the appropriate cabinets/bins is to provide a physical barrier to delay the involvement of the stored materials in a fire and provide sufficient time for people’s safe evacuation and the duty holder’s immediate emergency procedures supporting this to be implemented.

It is the responsibility of the employer/duty holder to ensure that cabinets/bins meet the minimum legal requirements. Equally, the use of cabinets/bins with enhanced fire performance should not be seen as a substitute for the provision of a dedicated store room(s) and outdoor storage areas for the safe keeping of containers which are nominally empty or are not needed for current work.

It’s important not to overlook any aspect associated with the safe handling of flammable liquids such as static discharge during filling/decanting, combustion due to excessive heat build-up, potential ignition sources such as a spark from a tool or electrical component and pressure build-up in a container.

Please remember to consult with your insurance provider and local authority fire brigade as they will have valuable input that could save you time and money going forward.

An outside pair of eyes will often see things that have become commonplace to you, so you might want to consider using the services of an outside company to assess/review your site.

Emtez is an ISO 9001, ISO 14001 & ISO 45001 accredited company with more than 35 years’ experience of manufacturing spill containment and spill response products and we are happy to offer a free of charge and without onus site assessment to anyone responding to this article quoting FLAM2020.
 
Features and benefits of an Emtez flammable liquids storage unit:

*Unless certain options such as electrics have been specified