Glossary / Physical hazards
Oxidizer
An oxidizer is a chemical that can cause or intensify a fire by supplying oxygen or by reacting strongly with combustible material. Many oxidizers do not burn themselves, but they make fuels ignite more easily and burn far more fiercely.
Explanation
Fire needs fuel, heat and an oxidizing agent. In ordinary fires the oxidizer is the oxygen in air. Oxidizing chemicals supply that third ingredient from their own structure, so a fire can keep going in places where air is limited and can be much harder to put out.
Common examples include nitrates, chlorates, perchlorates, permanganates, peroxides, bleach-type hypochlorites and concentrated nitric acid. Some oxidizing gases, such as pure oxygen, are also covered. Under the GHS, oxidizing liquids, solids and gases are separate hazard classes. Oxidizing liquids and solids are divided into three categories by how strongly they promote combustion; oxidizing gases have a single category.
The danger is mostly about contact. An oxidizer stored beside oils, solvents, paper, wood or powdered metals can start a fire from friction, a small spark or a leak, and contaminated oxidizers may react without any outside ignition source. Mixing an oxidizer with an organic material in a waste container is a classic cause of incidents.
Oxidizers are shown with the flame-over-circle pictogram. In the NFPA 704 diamond they appear as an OX symbol in the bottom white space.
What to do and watch for
- Store oxidizers away from fuels, solvents, reducing agents and combustible packaging, using physical separation rather than just distance on the same shelf.
- Never return spilled oxidizer to its container, and do not clean up with paper towels or sawdust, which can become fire hazards.
- Keep waste streams separate so oxidizers never end up in solvent waste.
Where it appears on an SDS
- Section 2: Hazard identification. Classification as an oxidizing liquid, solid or gas, the flame-over-circle pictogram and hazard statements such as H270, H271 or H272.
- Section 10: Stability and reactivity. Incompatible materials, conditions to avoid and any reactions with fuels or organic matter.
SDS content and wording vary by supplier. This page is general reference and does not replace the current SDS for your product.