An oxidizer is a chemical that is usually not itself combustible or flammable, but that initiates or promotes combustion in other materials through oxidation reactions. The intensity of the reaction depends on the oxidation-reduction potential of the materials involved; fire or explosion is most possible when strong oxidizing agents come into contact with easily oxidizable material, such as metals, metal hydrides or organics, especially flammable organic solvents. Exposure to heat, shock or friction can increase the explosive potential.
- Oxidizing materials can decompose readily at room temperature, or with slight heating, to produce oxygen. Elevated oxygen environments increase the risk of fire and explosion.
- When in contact with incompatible materials, oxidizers can:
- Speed up the development of a fire and make it burn more intensely.
- Cause materials that are normally not readily combustible in air to burn more readily.
- Cause combustible materials to burn spontaneously without a source of ignition.
* Incompatible materials include paper, wood, flammable and combustible chemicals, grease, waxes, cloth and many plastics that can act as a source of fuel.
- Inorganic peroxides react vigorously with water to release oxygen. Contact with organics and other oxidizable materials can result in fire.
- Organic peroxides (carbon-based compounds containing peroxy groups: -O-O-) are unstable, highly reactive and extremely flammable in the dry crystalline state. They are sensitive to heat, friction, impact, light and strong oxidizing agents
- Nitrates enhance the combustion of other materials and can give off irritating or toxic fumes in a fire. Some nitrates become shock sensitive when mixed with organic materials.
- Perchlorates are normally stable, but may become explosive when mixed with combustible materials.
- In general, oxidizers are corrosives and have similar health hazards to corrosives.
- Contact with skin causes redness, irritation, and possibly burns.
- Inhalation may cause respiratory tract irritation, sore throat, and possible burns. May lead to nausea, dizziness, drowsiness, headache, shortness of breath, rapid heart rate, pulmonary edema, or death.
- Ingestion may cause severe digestive tract irritation, nausea, vomiting, and burns potentially leading to severe and permanent damage or death.
- Chronic health effects are related to hematological and neurological changes. Absorption of some oxidizers has been associated with liver and kidney disease and cancer.
Handling and Use (Hazard Control)
- All procedures involving oxidizers should be performed in well ventilated areas, preferably in a fume hood, to prevent a buildup of oxygen.
- Safety shields should be used when reactions are expected to be highly exothermic or if there is a risk of splash or explosion.
- Follow these safe work practices:
- The quantity of oxidizer should be kept to the minimum necessary for the procedure. Do not leave excessive amounts in the vicinity.
- When working with, or storing, oxidizers it important to keep them away from all combustible materials including paper, wood, flammable and combustible chemicals, grease, waxes, cloth and plastics that are sources of fuel.
- Do not use oxidizers around open flames or oil baths (source of fuel). When necessary, heat reactions involving oxidizers with heating mantles, water baths or sand baths.
- Even a trace contamination of a stock container of oxidizing material can lead to fire or explosion. To avoid contamination transfer the required amount to a secondary container and do not return unused material to the original container.
- Remove contaminated clothing, footwear etc. as they can pose fire hazards.
- Be sure that oxidizers are not shock sensitive before chipping or grinding lumps to break them up. If crystals have formed in containers, get help for safe handling and disposal.
- Store oxidizers in containers made of inert material, such as glass, on fire resistant shelving.
- Do not store in the same area as potential fuel sources and keep segregated from dehydrating agents (e.g. sulfuric acid) and reducing agents.
- Do not use organic material, such as paper towels, to clean up spills.
Working with Perchloric acid
At room temperature and at concentrations less than 72%, perchloric acid is a corrosive like most other strong acids. At increasing concentrations or with heating, perchloric acid becomes a strong oxidizer that is prone to spontaneous and explosive decomposition. Anhydrous perchloric acid (>85%) is very unstable and may explode when it comes into contact with organic materials.
- All work with perchloric acid should be performed in a Perchloric Acid Fume Hood. All work involving heating of perchloric acid must be done in a Perchloric Acid Fume Hood.
- Perchloric Acid Fume Hoods are made of stainless steel (no wood) and have a water flush system to prevent the buildup of perchloric acid crystals.
- When possible, substitute with less hazardous chemicals or use more dilute solutions (<60%).
- Always maintain perchloric acid in an appropriate secondary container away from all other chemicals and organic materials, including wood, paper, and cloth.