Guide
Chemical Storage Compatibility: What Can Be Stored Together
Chemicals should be stored by hazard class and compatibility, not alphabetically. The main rule is to keep apart materials that react dangerously with each other, such as acids and bases, oxidizers and flammable or combustible materials, and acids and anything that can release a toxic gas (cyanides, sulfides). The SDS Sections 7 and 10 list incompatible materials for each product.
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Why segregation matters
Most serious storage incidents involve a spill, leak or fire that brings two chemicals together. Segregation reduces what can go wrong during that event. It is a design decision: shelves, cabinets, secondary containment trays and distance are the controls. A well-labeled shelf cannot help if bottles that react with each other sit side by side in the same tray.
Where the SDS tells you what is incompatible
Two sections matter: Section 7, conditions for safe storage including incompatibilities, and Section 10, with incompatible materials and conditions to avoid. Read them for every product on a shelf, not just the one you are placing. The hazard classes in Section 2 give a first sorting: flammable, oxidizing, corrosive, toxic and so on.
The main groups to keep apart
| Group | Keep away from | What can go wrong |
|---|---|---|
| Oxidizers (for example nitrates, peroxides, hypochlorite) | Flammable and combustible materials, organics, reducing agents | Fire or violent reaction; oxidizers feed fires |
| Flammable liquids | Oxidizers, ignition sources | Fire and explosion |
| Acids | Bases, cyanides, sulfides, active metals; keep organic acids apart from oxidizing acids | Heat, toxic gases such as hydrogen cyanide or hydrogen sulfide, hydrogen release |
| Bases (alkalis) | Acids, some metals, ammonium salts | Heat; release of ammonia from ammonium salts |
| Water-reactive materials (alkali metals, some hydrides) | Water, aqueous solutions, sprinklers where practical | Fire, hydrogen |
| Toxic materials | Acids that could liberate toxic gas; secure storage | Toxic exposure |
| Compressed gases | Heat sources; secure upright; separate oxidizing from flammable gases | Cylinder failure, fire |
Some familiar household pairs follow the same logic: bleach mixed with ammonia-containing products or with acids can release toxic gases. The product labels usually warn about this, so never combine cleaners.
A simple segregation plan
- List what you have using your chemical inventory, with hazard classes.
- Sort into storage groups: flammables, oxidizers, corrosive acids, corrosive bases, toxics, water-reactives, gases, and general low-hazard items.
- Give each group its own area: separate cabinets, shelves or rooms, with secondary containment such as trays that match the group so that a leak from one does not meet another.
- Handle the exceptions: products with more than one hazard go with the most restrictive one, then check for incompatibility with neighbours.
- Put heavy and liquid items low and keep bottles off the floor and out of walkways.
- Label shelves with the group name and the incompatible groups.
- Review after each delivery.
Quantity and fire code limits
The SDS gives hazard information, not legal storage quantity limits. Fire codes and OSHA rules often limit the amount of flammable liquid outside an approved cabinet or storage room, and may require approved cabinets, ventilation and fire protection. Check the rules that apply to your jurisdiction and ask your fire authority or insurer. See Section 5 for fire response and the NFPA 704 diamond for building signage.
Common mistakes
- Alphabetical storage that puts an acid next to a cyanide or an oxidizer next to a solvent.
- Sharing a spill tray between incompatible groups.
- Storing chemicals above eye level or on high shelves without a safe way to reach them.
- Leaving old or unlabeled bottles; see secondary container labels.
- Forgetting waste: waste containers are chemicals too and need the same segregation; see Section 13.
- Storing peroxide-forming solvents indefinitely without dating them.
Frequently asked questions
Can acids and bases be stored on the same shelf?
No. Store them in separate areas with separate secondary containment. A spill that combines them can release heat and splash corrosive liquid.
Where do I find incompatibilities for my chemical?
In Sections 7 and 10 of the SDS, which list conditions for safe storage, incompatible materials and conditions to avoid.
Is it safe to store flammables with oxidizers if they are in separate bottles?
No. Oxidizers can intensify a fire of flammable materials. Keep them in different cabinets or separate areas.
Do I need special cabinets?
Often for flammable liquids and corrosives above certain quantities, but the legal requirements come from fire codes and OSHA, not from the SDS. Check the rules for your location.