Chemical Storage and Compatibility: How to Segregate a Warehouse

Many chemical accidents do not come from a failed process, but from a storage mistake: two products placed side by side that react when a container leaks, tips or burns. Chemical segregation is the practice of separating incompatible products so that a leak of one cannot reach another. It is cheap compared with the cost of an incident, and it is a basic duty under most workplace and fire codes.

Where the SDS tells you what to do

Two sections carry the information. Section 7 (handling and storage) gives conditions for safe storage, including temperature limits, ventilation, container material and incompatible materials. Section 10 (stability and reactivity) lists conditions to avoid, incompatible materials and hazardous decomposition products. Read both before assigning a storage place. Our guide to the 16 sections explains how these sections work together.

The main segregation groups

• Acids and bases: keep them apart because neutralisation releases heat, and acids and bases with certain metals release hydrogen. A caustic soda spill reaching a drum of acid can boil and spatter. See caustic soda and sulfuric acid.
• Oxidising agents and flammables or combustibles: oxidisers such as nitric acid, permanganates, nitrates and peroxides feed fires and can ignite organics. Keep them away from solvents, paper, wood, oils and reducing agents. See nitric acid and potassium permanganate.
• Flammable liquids: store in ventilated flammable-liquid cabinets or rooms, grounded, away from ignition sources. See acetone.
• Water-reactive materials: alkali metals, carbides and some hydrides produce flammable gas on contact with water. Keep dry, with no sprinklers or water sources directly above where rules allow.
• Toxic and highly toxic substances: store in locked, labelled areas with limited access and spill containment.
• Bleach and acids, and bleach and ammonia: these create toxic gases, as covered in our bleach guide.
• Cyanides and sulphides with acids: contact releases hydrogen cyanide or hydrogen sulphide gas, and so these must be separated from all acids.

Layout and good practice

Segregate by a physical barrier, distance or a separate bund or tray, not just a label. Store heavier or more hazardous items low, never above eye height, and never put liquids above solids that react with them. Use secondary containment sized for the largest container, with separate trays for acids and bases. Keep aisles clear, label shelves by hazard class, and use compatible shelving, since acid fumes corrode steel. Keep storage within allowed quantity limits, which are set by fire codes for flammables and oxidisers.

Containers matter too. Use original or approved containers with intact labels, close them tightly, and check for corrosion, bulging or leaks during regular inspections. Never store chemicals in food or drink containers. Date containers when opened, because some materials, such as ethers and isopropanol, can form peroxides over time.

Document your plan

A simple compatibility matrix, created from the SDS data of each product, makes it easy for staff to see what can sit next to what. Maintain a current inventory with quantities and locations, share it with the emergency services where required, and review it whenever you add a new product. Many incidents happen when a new chemical is placed in a convenient free space. When you add a product, check its hazard classes first, and its SDS second.

Training and emergency planning

Staff should know where spill kits, eyewash stations and extinguishers are, which kit suits which spill, and what the first-aid steps are. Run drills, and keep copies of SDSs available in the workplace. These requirements echo workplace rules such as the OSHA Hazard Communication Standard, covered in our HazCom guide.