Storage of hazardous substances

If you store hazardous substances in a company, laboratory or workshop, such as flammable liquids, acids, alkalis, gas cylinders or lithium-ion batteries, you have to deal with the federal rules on well-being at work and with the environmental rules of your region. This guide to the storage of hazardous substances sets out those rules, explains the difference between flammable and combustible, and shows which cabinet suits each product group.

Flammable or combustible: what is the difference?

The difference lies in the flash point: the lowest temperature at which a liquid gives off enough vapour to ignite. The Belgian Code on well-being at work classifies liquids as follows (art. III.5-2):

Class under the Code	Flash point	Examples
Extremely flammable	below 0 °C, boiling point up to 35 °C	petrol, diethyl ether (ether), acetaldehyde
Highly flammable	below 21 °C	acetone, ethanol and methylated spirits, isopropanol (IPA), methanol, toluene, ethyl acetate, special boiling point spirit (cleaning benzine), petroleum ether (boiling from 40 °C), cellulose and nitro thinners, many contact adhesives and brake cleaners
Flammable	21 to 55 °C	white spirit, turpentine, xylene, paraffin and kerosene, glacial acetic acid, many paints and varnishes based on white spirit
Combustible	55 to 100 °C	diesel, heating oil, butyl glycol (in some cleaners)

Extremely and highly flammable liquids can therefore ignite at room temperature; a combustible liquid only gives off enough vapour once it is heated. Labels and safety data sheets follow the European CLP classification, with H224 (extremely flammable), H225 (highly flammable) and H226 (flammable). Its limits (23 and 60 °C) differ slightly from those of the Code. That is why diesel and heating oil often carry H226: CLP allows this for gas oil with a flash point up to 75 °C.

For mixtures such as paints, adhesives and cleaners, the flash point of the mixture counts, not that of a single ingredient. You will find it in section 9 of the safety data sheet. Water-based products are usually not flammable. Engine oil, hydraulic oil, grease and frying oil have a flash point well above 100 °C and fall outside this classification.

Aerosols such as spray paint, brake cleaner or penetrating oil have their own CLP classification (H222 and H223) and are not covered by this table. Their propellant is usually highly flammable, so they too are best kept in the cabinet for flammable liquids.

Examples by workplace

The products you store depend largely on your activity. A few examples:

Workplace	Typical products
Garage and workshop	petrol, diesel, brake cleaner, degreaser, aerosols, battery acid, gas cylinders for welding (acetylene, oxygen), power tool batteries
Painter, joiner and renovation	thinner, white spirit, acetone, solvent-based lacquer and varnish, contact adhesive, propane cylinders for torches
Laboratory and education	ethanol, methanol, acetone, ether, toluene, glacial acetic acid, hydrochloric acid, sulphuric acid, caustic soda, gas cylinders
Cleaning, maintenance and care	isopropanol and disinfectant alcohol, methylated spirits, descalers (acidic), drain cleaners and bleach (alkaline), device batteries
Production and industry	solvents and cleaners in drums or jerrycans, adhesives and resins, process gases, tool batteries

Each group needs its own cabinet: for flammable liquids, for acids and alkalis, for gas cylinders and for batteries. Below you can read what to look out for in each group.

What the law requires at work

Book III, title 5 of the Code on well-being at work applies from 50 litres of extremely and highly flammable liquids, 500 litres of flammable liquids or 3,000 litres of combustible liquids (art. III.5-1). Storage means a quantity that exceeds one day's use (art. III.5-2). Extremely flammable, highly flammable and flammable liquids in mobile containers must then be kept in a storage area or in a safety cabinet (art. III.5-6).

An example: a garage with two 20-litre jerrycans of petrol and a 10-litre can of acetone holds 50 litres of extremely and highly flammable liquids in stock. From that quantity, title 5 applies.

The General Regulation for Labour Protection (ARAB) also requires flammable or toxic liquids and gases in workshops to be limited to the strict minimum, in unbreakable containers that close hermetically; in laboratories, glass is allowed up to 3 litres (art. 52.8.4). Book VI of the Code also asks employers to keep the quantity of chemical agents at the workplace as small as possible and to store incompatible products separately (art. VI.1-12 and VI.1-20).

Under the Code, a safety cabinet is made of non-combustible material. It must:

have a spill sump that holds at least the largest container and at least a quarter of all containers together (art. III.5-7 and annex III.5-1);
have doors that close by themselves in a fire (art. III.5-7);
be adequately ventilated (art. III.5-11).

Containers stay closed and protected from the sun and heat sources (art. III.5-12). Smoking and fire are prohibited, indicated with a pictogram (art. III.5-47), unauthorised persons have no access (art. III.5-64), and other substances may only be stored with the liquids if they do not increase the risk and do not react dangerously with them (annex III.5-1, point 3). Work with fire in the storage area requires the employer's prior written permission (art. III.5-48), and spills on the floor must be prevented when handling the liquids (art. III.5-57); keep absorbent material at hand for this.

If you opt for a separate storage room, building rules also apply. From 50 litres of liquid with a flash point up to 21 °C, 500 litres between 21 and 50 °C or 300 litres of combustible gas, the ARAB requires walls and self-closing doors with at least half an hour of fire resistance (art. 52.2 and 52.3).

Notification or permit: thresholds by region

Besides the federal rules, the region determines from which quantity you must notify the storage or need an environmental permit. The quantities apply to the whole site, added together. The lowest thresholds:

Region	Notification from	Permit from
Flanders (Vlarem)	packaging up to 30 litres, 50 to 5,000 litres or kg in total: notification (heading 17.4); otherwise CLP categories 1 and 2 from 50 kg, category 3 from 100 kg; gas cylinders: from 300 litres water capacity	categories 1 and 2: over 2 tonnes; category 3: over 10 tonnes; gas cylinders: over 1,000 litres
Brussels (Brussels Environment)	flash point 21 to 55 °C: 100 litres; 55 to 100 °C: 3,000 litres	flash point up to 21 °C: 50 litres; 21 to 55 °C: over 500 litres; 55 to 100 °C: over 10,000 litres; gas cylinders: 300 litres
Wallonia (SPW)	CLP category 1: 50 litres; category 2 (including petrol): 100 litres; category 3, diesel and heating oil: 3,000 litres; propane and butane: over 300 litres	category 1: 500 litres; category 2: 5,000 litres; category 3: 25,000 litres; propane and butane: over 700 litres; other gases: over 500 litres

Flanders and Wallonia use the CLP categories on the label (category 1 = H224, 2 = H225, 3 = H226); Brussels uses the flash point.

In Brussels, any change requires prior authorisation: other or more products, or a different type of safety cabinet. If in doubt, ask your municipality which heading applies to your storage.

Flammable liquids: standard and spill sump

Cabinets for flammable liquids are covered by the European standard EN 14470-1. The type (15, 30, 60 or 90) states for how many minutes the temperature inside the cabinet rises by no more than 180 K in an external fire. In Brussels, safety cabinets installed after 1 January 2006 must comply with this standard.

Belgian rules do not prescribe a particular type. The type you need follows from the risk assessment, your permit or the fire service's advice. We explain the difference between type 30 and type 90 with our safety cabinets for flammable products.

Watch the spill sump: the standard asks for 10 % of the total contents or 110 % of the largest container, but the Code is stricter and requires at least the largest container and a quarter of the total. How the standard tests the cabinet and what closes by itself in a fire is explained on our page about EN 14470-1.

A worked example: a cabinet holds ten 5-litre cans and two 20-litre jerrycans, 90 litres in total. The standard then requires 22 litres of containment, because 110 % of 20 litres is more than 10 % of 90 litres. The Code requires 22.5 litres, because a quarter of 90 litres is more than the largest container.

Extraction and ventilation

Every storage area must be adequately ventilated, naturally or mechanically (Code, art. III.5-11). A cabinet to EN 14470-1 has supply and exhaust openings for this, which close by themselves at around 70 °C in a fire. Whether the cabinet needs to be connected to mechanical extraction depends on the substances, the quantity and the room.

In Brussels, Brussels Environment requires exhaust directly to the outside or to a room that is itself ventilated to the outside, through openings that are as fire-resistant as the cabinet or fitted with fire dampers. With mechanical ventilation, at least ten times the cabinet volume must be renewed per hour. Asecos states the required air flow for each cabinet. We connect the cabinet to an existing extraction duct; we do not install the duct itself.

Acids and alkalis

Acids and alkalis are usually not flammable, but they are corrosive: they attack metal, packaging and each other. Common acids are hydrochloric acid, sulphuric acid (also in battery acid), nitric acid, phosphoric acid and the acids in descalers. Common alkalis are caustic soda (sodium hydroxide, also in drain cleaners), caustic potash, ammonia solution and bleach.

The employer must store incompatible chemical agents separately (Code, art. VI.1-20), and in Brussels, Brussels Environment requires separate compartments, each with its own sump. Acids and alkalis are therefore kept apart. Bleach releases toxic gases with an acid or with ammonia; keep it away from both. Oxidising substances such as hydrogen peroxide and nitric acid do not belong with flammable liquids. Glacial acetic acid is both corrosive and flammable, so it belongs in a cabinet for flammable liquids, away from alkalis.

The cabinets for this purpose have separate compartments in corrosion-resistant material. They are not fire-resistant: if flammable liquids must be stored as well, choose a combination cabinet with a fire-resistant section. See our cabinets for acids and alkalis.

Gas cylinders

For gas cylinders inside a building, the standard EN 14470-2 applies, with type G30 or G90. During those 30 or 90 minutes, the temperature at the valve holder of the cylinder may not rise by more than 50 K in a fire. The cabinet ventilates its entire interior: at least ten air changes per hour for flammable or oxidising gases and 120 for toxic gases.

Common gases fall into four groups. Flammable: propane, butane, acetylene and hydrogen. Oxidising: oxygen and nitrous oxide; they do not burn themselves but intensify a fire, and they should not stand next to flammable gases or liquids. Asphyxiant: nitrogen, argon, carbon dioxide (CO2) and helium; when they leak, they displace oxygen, especially in small or poorly ventilated rooms. Toxic: including ammonia and carbon monoxide. Secure cylinders upright with a strap or chain.

The ARAB prohibits propane or butane cylinders in basements; empty or unused cylinders are kept outdoors or in a ventilated room intended for that purpose (art. 52.6). From 300 litres water capacity of combustible gas, the ARAB building rules apply to a storage room, and the regions also set their first threshold between 300 and 500 litres. For outdoor use, there are galvanised cabinets with ventilation and a roof. More in our gas cylinder cabinets.

Lithium-ion batteries

A lithium-ion battery can catch fire by itself after a fall, because of a manufacturing defect or during charging, and the fire can spread to other batteries. The rules above concern liquids and gases and contain no specific provisions for batteries; the employer includes them in the risk assessment. A battery cabinet must protect in two directions: against an external fire and against a fire that starts inside the cabinet. The German test method VDMA 24994 tests exactly that; read more in our explanation of fire-resistant storage of lithium-ion batteries.

Think of power tool batteries, batteries from e-bikes and e-scooters, laptops, tablets and phones, power banks and drones.

The first choice is whether you only store batteries or also charge them. For storage without charging, a fire-resistant battery cabinet is enough; for charging, you need a charging cabinet with sockets in a fire-protected compartment, smoke and temperature detection and alarm forwarding. Belgian rules set no number of batteries per cabinet: the limit comes from the cabinet, above all the maximum battery energy in kWh stated by the manufacturer, and from your risk assessment. Add up the watt-hours of all batteries (voltage times capacity) to check it. Keep damaged batteries separate and report charging points to the emergency services through the intervention file. See our safety cabinets for batteries.

Six steps to correct storage

From a list of products to the right cabinet in the right place:

Make a list of all products, with the quantity and type of packaging.
For each product, look up in the safety data sheet the hazard statements (section 2), the storage conditions (section 7), the flash point (section 9) and the substances it must not be stored with (section 10).
Add up the quantities per class and compare them with the Code and with the thresholds in your region.
Divide the products into groups that may be stored together and choose the cabinet and its size for each group, with a sufficient spill sump.
Choose the location and check whether the cabinet needs to be connected to extraction.
Keep the storage in order: doors closed, pictograms visible, sump clean and your staff informed of the rules (Code, art. III.5-62 to III.5-65).

Email us that list and we will help with steps 4 and 5.

Reading an Asecos order number

The model name of an Asecos cabinet tells you what you are buying. In G90.205.120, G90 stands for a type 90 gas cylinder cabinet, 205 for the height in centimetres and 120 for the width. In UB90.080.110.060.2S, the type is followed by the height, width and depth, and 2S means two drawers (2T: two doors).

The order number itself has three parts: the cabinet, the colour and the interior fittings. For example, the Q90.195.060 with a golden yellow door (RAL 1004) has the number 30072-040-30076, and with a light grey door (RAL 7035) 30072-041-30076. We put the correct number in your quotation.

Name	Expiration	Description
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What the law requires at work

Where may the cabinet stand?

Extraction and ventilation

Acids and alkalis

Gas cylinders

Lithium-ion batteries

Frequently asked questions

Storage of hazardous substances

In this guide

Flammable or combustible: what is the difference?

Examples by workplace

What the law requires at work

Notification or permit: thresholds by region

Where may the cabinet stand?

Flammable liquids: standard and spill sump

Extraction and ventilation

Acids and alkalis

Gas cylinders

Lithium-ion batteries

Six steps to correct storage

Reading an Asecos order number

Delivery and installation

Frequently asked questions

Official sources