What Size COSHH Cabinet Do I Need?
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What size COSHH cabinet do I need?
Choosing a COSHH cabinet isn't about what fits the gap in the corner — it's about the right volume, the right substances, and staying the right side of the regulations. Here's how to size yours properly.
By the Cocus team · 6 min read
The short version
- As a rule of thumb, up to 50 litres of flammable liquid can be kept in a workroom in a fire-resistant cabinet before extra controls apply.
- Size on the volume of your containers, not the liquid inside them — and leave room to grow.
- Different substances need different cabinets: general COSHH, flammable (DSEAR), and pesticide/agrochemical.
- Your sump must hold at least 110% of your largest container to catch a spill.
Start with the law, not the shelf
The size of cabinet you need is partly a compliance decision, not just a storage one. The Control of Substances Hazardous to Health Regulations 2002 (COSHH) require you to store hazardous substances safely and securely. Where those substances are flammable, the Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) add specific rules.
The figure most people reach for is a general rule of thumb: up to 50 litres of flammable liquid can typically be kept in a workroom provided it's in a suitable fire-resistant cabinet. Larger, less volatile stocks may be handled differently, and going well beyond that usually means separate storage and additional controls. So before you measure the space, work out roughly how much you actually store — and let your own risk assessment set the limit.
How to work out the size you need
Sizing a cabinet is a three-step job. Don't guess from the liquid volume alone — a "20 litre" stock of solvent might be spread across a dozen awkwardly-shaped tins that need far more shelf space than 20 litres suggests.
Cabinet formats and capacities
Once you know your total volume plus headroom, match it to a format. Broadly, there are four to choose from:
| Format | Typical capacity | Best for |
|---|---|---|
| Countertop / under-bench | Small (approx. 5L sump) | Labs, workshops and low-volume storage where space is tight |
| Wall-mounted | Small–medium | Saving floor space while keeping substances secure and off the ground |
| Floor-standing (single/double door) | Medium–large | The workhorse — most sites with a mix of solvents, paints and chemicals |
| Drum storage / bunded | Very large (drums & IBCs) | Bulk storage of 205L drums or intermediate bulk containers |
Match the cabinet to the substance
Capacity is only half the decision. The type of cabinet has to suit what's going inside it:
General COSHH cabinets suit acids, corrosives and non-flammable chemicals. Flammable liquid cabinets (fire-resistant, and often FM-approved or built to EN 14470-1) are required for solvents, paints and fuels under DSEAR. Pesticide and agrochemical cabinets are a dedicated category for agricultural chemicals, in line with the Food and Environment Protection Act.
Never mix incompatible substancesFlammables and oxidising agents stored together are a serious fire and reaction risk. If you hold both, that's two cabinets — factor it into your sizing from the start.
Don't forget the sump
Every compliant cabinet has a bunded sump in the base to catch leaks and spills. As a rule, the sump should hold at least 110% of the volume of your largest single container, or 25% of the total stored — whichever is greater. It's an easy detail to overlook when you're focused on shelf space, but it's the bit an inspector will check.
Buy one size upStorage needs almost always grow. A cabinet that's 80% full on day one leaves no room to segregate a new substance safely — sizing up front is cheaper than buying twice.
Frequently asked questions
What's the maximum flammable liquid I can store in a workroom?
As a general guide, up to 50 litres of flammable liquid can be kept in a workroom in a suitable fire-resistant cabinet. Larger or bulk quantities usually need a dedicated, separated store with additional controls under DSEAR. Your own risk assessment — and, for significant quantities, a conversation with your local authority or fire officer — should set the actual limit for your site.
Do COSHH cabinets need to be ventilated?
It depends on what's stored. Cabinets holding volatile or flammable substances should be ventilated to stop vapour building up — many flammable cabinets have ventilation ports fitted with mesh flame arrestors. Always check the safety data sheet for the substance.
Can I store different chemicals in the same cabinet?
Only if they're compatible. Incompatible substances — flammables and oxidisers, or acids and alkalis — must be segregated to prevent dangerous reactions. This is one of the main reasons to build headroom into your sizing.
Does a COSHH cabinet need to be fire-rated?
Not all do, but it's strongly recommended for flammable substances. A fire-resistant cabinet buys valuable time to react and evacuate in a fire, and is expected under DSEAR for flammable liquid storage.
Where should a COSHH cabinet be located?
Away from ignition sources and heat, and clear of exits and escape routes so a fire can't trap anyone. A well-ventilated area is best, and flammable stores should be sited to limit fire spread. Let your fire risk assessment guide the exact position.
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