Chemical storage
Chemical incompatibility: the storage mistakes that cause fires
Store chemicals by hazard class, not alphabetically. A shelf arranged A to Z can put acetic acid next to an oxidiser.
Many chemical store incidents begin with no handling error at all. Two incompatible substances leak, mix or react while sitting side by side. The result can be heat, fire, explosion or toxic gas. Chemicals must be segregated by hazard class and compatibility, using the SDS (Sections 7 and 10) and a compatibility chart.
The incompatible pairs every storekeeper should know
| Combination | What can happen |
|---|---|
| Acids + bases | Violent neutralisation, heat and spattering |
| Acids + cyanides or sulfides | Release of highly toxic gas (hydrogen cyanide, hydrogen sulfide) |
| Flammables + oxidisers | Fire or explosion |
| Organics (oil, grease, solvents) + strong oxidisers (peroxides, nitric acid, permanganates) | Fire or explosion |
| Acids + chlorates or hypochlorites (bleach) | Toxic gas (chlorine, chlorine dioxide) |
| Corrosives + metals | Heat and flammable hydrogen gas |
| Water-reactive substances (sodium, carbides, hydrides) + moisture | Fire, explosion, flammable gas |
| Ammonia + chlorine or bleach | Toxic chloramine gas |
Simple segregation rules
- Store by hazard group in separate areas or cabinets: flammables, oxidisers, acids, bases, toxics and gases.
- Keep flammables in approved flammable-liquid cabinets, away from oxidisers and ignition sources.
- Store corrosives low, in trays or bunds, with acids separated from bases.
- Keep water-reactive chemicals dry and away from sprinklers and wash areas.
- Chain gas cylinders upright, and keep oxygen at least 6 m from flammable gases or behind a fire-rated barrier.
- Label every storage zone and keep a compatibility chart at the store entrance.
Before placing a new chemical in a shared store, check SDS Section 10 (stability and reactivity) for the substances it must be kept away from. Then check what is already stored nearby.
What to do
- Walk your store with an incompatibility chart, and move anything stored only by alphabet or convenience.
- Use separate secondary containment for incompatible groups, so a single leak cannot reach another group.
- Include compatibility checks in receiving procedures and inspections.
How INRC can help
Our occupational health and safety inspections walk your chemical stores with a compatibility chart and set out a practical re-arrangement plan. Our environmental audits track the actions to closure. Contact us to discuss your site.
This article is general guidance, not legal advice. Check current legislation and regulations for your specific project.