Office of Environmental Health and Safety
Chemical Hazard Class and Storage Information
| DOT Hazard Class | Definition | Examples | Hazards | Storage (Also see Incompatible Chemicals) |
| Class 1 Explosive/Shock Sensitive | Thermodynamically unstable material. | picric acid, 2,4-dinitro-phenol, organic azides | Explosion caused by shock or chemical reaction. | Follow manufacturer's recommendation. Discard before expiration date. Store minimum quantities. |
| Class 2: Gases | ||||
| Flammable Gas | Gas with a flash point less than 140° F. | carbon monoxide, hydrogen, oxygen | Ignites easily, burns rapidly. | Store away from ignition sources and oxidizers. Secure with a double chain to prevent falling. Store oxygen away from flammable gases. Check connections regularly to avoid leaking. |
| Non-Flammable Gas (including compressed gas) | Non-flammable, purified gas in a pressurized tank. | nitrogen, carbon dioxide | Tank rupture, fire, toxic atmosphere, oxygen displacement | Store upright, secure with a double chain to prevent falling. Check connections regularly to avoid leaking. |
| Class 3 Flammable Liquid | Liquid with a flash point less 140° F. | methanol, acetone, acetaldehyde | Ignites easily, burns rapidly. | Store in flammable storage cabinet, away from ignition sources and oxidizers. Quantities should not exceed 10 gallons. |
| Class 4 Flammable Solid | Solid that burns readily. | sodium | Ignites easily, burns rapidly. | Store in flammable storage cabinet, away from ignition source and oxidizers. |
| Class 5.1 Oxidizer | Agents that react with reducible material to initiate or promote combustion. | nitric acid, bromine | Fire or explosion. | Store away from organics and flammables. Do not store directly on wooden shelves or paper. Store chlorine separately from acids. |
| Class 5.2 Organic Peroxide
| Any organic compound that forms unstable peroxides when exposed to air. | diethyl ether | Explosion resulting from formation of concentrated peroxide crystals. | Dispose before expiration date. If there is no marked expiration date, label with receipt date and maintain for no more than 1 year or 6 months after opening. |
| Class 6 Poison Toxic Highly Toxic | Chemicals that cause damage to target organs (liver, lungs, reproductive system, etc.) if inhaled, ingested, or absorbed through the skin. Toxic chemicals have an LD50 of 50 - 500 mg/kg, single oral dose for rats. Highly toxic chemicals have an LD50 of < 50 mg/kg, single oral dose for rats. | chloroform, chromic acid, phenol, acetonitrile | Acute or toxic effects that may be local, systemic, or both. | Store in a secure, sealed container below shoulder level. Use only in designated areas. Store away from incompatibles. |
| Class 8: Corrosive |
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| Organic Acids | Compound with pH of 1-7, containing carbon. | phenol, acetic acid | Tissue damage, violent reaction with strong bases. | Segregate from mineral acids, oxidizing acids and bases. |
| Inorganic Acids | Compound with pH of 1-7, not containing carbon. | hydrochloric acid, sulfuric acid, boric acid | Tissue damage, violent reaction with strong bases. | Segregate from organic acids, oxidizing acids and bases. |
| Caustics | Compound with pH of 7-14. | sodium hydroxide, potassium hydroxide | Tissue damage, violent reactions with strong acids. | Segregate from mineral acids, organic acids, and oxidizing acids. |
| Class 9: Miscellaneous |
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| Water Reactive | Reacts violently when exposed to water producing heat or toxic gases. | sodium metal, acid anhydrides, metal anhydrides | Explosion, fire, toxic atmosphere | Store away from water, including sprinkler heads, sinks and drains, per manufacturers instructions. |
| Pyrophoric | Ignites spontaneously in air. | Phosphorus, lithium | Fire | Store under inert atmosphere per manufacturers instructions. |
| Carcinogen | Chemicals that cause cancer in humans or animals models. | formaldehyde, benzene | Carcinogenesis | Store in a secure, sealed container below shoulder level. Use in only designated areas with approved controls. Store away from incompatibles. |
| Cryogen | Liquefied or solidified gases at low temperatures. | liquid nitrogen, dry ice | Tissue damage (frost bite), oxygen displacement, tank rupture | Store in approved containers. Store in well ventilated areas. (Do not store dry ice in cold rooms.) Design transfer lines such that liquids cannot be trapped in a non-ventilated part of the system. |
| Sensitizer | Substances that can cause an allergic reaction of the skin or respiratory system. | glutaraldehyde, isocyanates | Allergic reaction. | Store in secure container taking into account other hazards associated with the substance. |
| Controlled Substances | Substances specifically controlled by federal law. | narcotics | Theft | Store in a secure, locked location. Maintain a current inventory. |
| Nonhazardous |
| Compatible Storage Classes | ||||
| Class | Definition | Examples | Hazards | Storage |
| Flammables | Gases and solvents with a flash point less than 140oF and solids that burn readily | methanol, acetone, acetaldehyde | Ignites easily, burns rapidly | Store in flammable storage cabinet , away from ignition sources and oxidizers |
| Organic Acids | pH 1-7 | bromic acid, nitric acid, phenol | Tissue damage, violent reaction with strong bases, Fire | Segregate from mineral acids, oxidizing acids and bases. |
| Inorganic Acids | pH 1-7 | hydrochloric; sulfuric, boric | Tissue Damage, violent reaction with strong bases | Segregate from organic acids, oxidizing acids and bases |
| Caustics | Bases (pH 7 – 14) | sodium hydroxide; potassium hydroxide | Tissue damage, violent reactions with strong acids | Segregate from mineral acids, organic acids, and oxidizing acids |
| Explosive/ Shock Sensitive | Thermodynamically unstable material | picric acid 2,4-dinitrophenol organic azides | Explosion caused by shock or chemical reaction | Follow manufacturer’s recommendation. Discard before expiration date. Store minimum quantities |
| Water Reactive | React violently when exposed to water to produce heat or toxic gases | sodium metal, acid anhydrides, metal anhydrides | Explosion, Fire, Toxic atmosphere | Store under inert atmosphere or oil per manufacturers instructions. |
| Peroxide Former | Form unstable peroxides when exposed to air | diethyl ether, sodium amide | Explosion resulting from formation of concentrated peroxide crystals | Store under nitrogen. Dispose before expiration date. If there is no marked expiration date label with receipt date and maintain for no more than 1 year. Mark the date opened and store for a maximum of 6 months after opening. Store minimum quantities. |
| Pyrophoric | Ignites spontaneously in air | phosphorus metal, lithium | Fire | Store under inert atmosphere per manufacturers instructions. |
| Oxidizer | Agents that reacts with reducible material to initiate or promote combustion | nitric acid, bromine, | Fire, explosion | Store away from organics and flammables. Do not store directly on wooden shelves or paper. Store chlorine separately from acids. |
| Poison | Chemicals that cause damage to target organs (liver, lungs, reproductive system, etc.) if inhaled, ingested, injected or absorbed through the skin. | chloroform chromic acid | Acute or chronic toxic effects that may be local, systemic or both. | Store in a secure, sealed container below shoulder level. Use only in designated areas. Store away from incompatibles. |
| Carcinogen | Chemicals that can cause cancer in humans or human models | formaldehyde, benzene | Carcinogenisis | Store in a secure, sealed container below shoulder level. Use only in designated areas with approved controls. Store away from incompatibles. |
| Cryogen | Liquefied or solidified gases at low temperatures | liquid nitrogen, dry ice | Tissue damage (frost bite), oxygen displacement, Tank rupture | Store in approved containers. Store in well ventilated areas. (Do not store dry ice in cold rooms.) Design transfer lines that liquids can not be trapped in a non-vented part of the system |
| Compressed Gas | Purified gas in a pressurized container | nitrogen, oxygen, carbon dioxide, carbon monoxide | Tank rupture, Fire, toxic atmosphere, oxygen displacement | Store upright, secure to prevent falling, check connections regularly to avoid leaking. Store oxygen away from flammable gases. |
| Controlled Substances | Substances specifically controlled by federal law | narcotics | Theft | Store in a secure, locked location. Maintain a current inventory. |
