Chemical Storage

The safe storage of hazardous chemicals is an essential part of laboratory safety. Chemical storage is complex—there is no one-size-fits-all plan to store chemicals—but there are regulations, campus requirements, and best practices that can guide the process. The general concept is to prevent chemicals from causing harm to people, property, other chemicals, or the environment.

In order to fully understand the hazards associated with stored chemicals you first need to know what chemicals are being stored. Safe storage begins with an up-to-date inventory of chemicals and knowledge of the hazards posed by each chemical

General Storage Requirements

• All chemicals must be stored in a safe, secure location.
• Shelves should be level, stable, and secured to the wall or another stable
• Store chemicals away from direct sunlight, sources of heat, and egress pathways
• Hazardous chemicals must be stored below eye level.
• Do not store chemicals on the floor, window ledges, or balconies.
• Keep containers closed unless you are dispensing a chemical or adding to the container.
• Provide secondary containment for liquids whenever possible. Dishpans or polyethylene trays work
• Don’t store chemicals in a sink or fume hood, except for certain toxic gases that are so dangerous they can only be stored in a gas cabinet or fume
• Label containers, and be sure container is compatible with the chemical
• Use rated storage cabinets or safety cans whenever possible—required for >10 gal. of flammables.
• Cold rooms, refrigerators, and freezers have additional requirements, particularly for flammables.

Chemical Segregation

Chemicals should always be segregated according to their specific hazard(s) to prevent unintended reactions. Begin by categorizing and separating chemicals by the following categories. Note that the order is intentional, as discussed below.

• Pyrophorics
• Water reactives
• Flammables
• Corrosives
• Oxidizers
• Toxics

Other types of materials require more specific storage requirements such as

• Explosives
• Compressed gases
• Cryogens

As a general rule, chemicals need to be physically segregated from incompatible chemicals; some key requirements are listed below.

• Store flammable liquids in approved safety containers in . Do not store anything but flammable or combustible liquids in these
• Segregate acids from
• Keep oxidizers away from flammables and combustibles.
• Keep corrosives away from substances that they may react with and release corrosive, toxic, or flammable vapors
• Do not store chemicals alphabetically unless they are compatible.

Multiple Hazard Classes

Many chemicals belong to more than one chemical family or hazard class. In many cases, chemicals need to be evaluated on a case-by-case basis. Ideally, guidelines for each category should be observed, but this may not be possible in all instances.

One strategy is to prioritize the hazards of a specific chemical. The hazards listed above are prioritized for this purpose, from most severe to least. A pyrophoric chemical, for example, may also be a flammable liquid, but the pyrophoric property should outweigh the flammability for storage purposes.

Glacial acetic acid is a common example, as it is both a corrosive acid and a combustible liquid. It should be stored away from corrosive bases, such as sodium hydroxide, and also from oxidizing acids, such as nitric acid. Storing acetic acid in a flammable storage cabinet would be appropriate, prioritizing the combustibility over the corrosivity. If flammable storage space is at a premium, storage in a corrosives cabinet would also be acceptable; however, it would need to be further segregated from the other incompatible corrosives by utilizing multiple cabinets or secondary containment.

Storage Limitations

It is best practice to minimize the quantities of hazardous chemicals on hand whenever possible. Minimization of stored chemicals is a key way to reduce the likelihood and severity of an incident involving said chemicals. Chemical storage limits, from various regulatory bodies and campus policy, are outlined in Appendix D of the campus Chemical Hygiene Plan. It is important to note that storage limitations, particularly based on fire code, often extend to large groupings of labs or even entire floors of buildings. Each space is different, so contact Chemical Safety staff for an evaluation.

Where to find information

The first source for chemical-specific information should be the labels and safety data sheets (SDSs) from the manufacturer. You may also contact Chemical Safety for advice. A poster is also available, providing chemical storage basics. One can be requested via our website.

Storage Cabinets and Safety Cans

Flammable storage cabinets

Flammable storage cabinets are designed to meet specific requirements outlined by various standards such as OSHA, NFPA, IFC, and UL. They are specifically constructed to contain flammable materials and slow the spread of a fire towards the materials in the cabinet.

When purchasing a cabinet for your lab, look for a cabinet which is OSHA and NFPA approved (which will fulfill UL 1275) and has self-closing doors to comply with IFC. If you have an existing cabinet, it should be labeled if it meets any of these standards. Contact chemical safety if you need further information on your available storage cabinets.

Flammable storage cabinets are not required to be vented, and it is not recommended to do so in most cases. Improper venting can negate the fire protection provided by a cabinet.

Safety Cans

A safety can is a rated container of not more than 5 gallons (20 liters) capacity having a screen or strainer in each fill-and-pour opening and having a spring-closing lid and spout cover designed to safely relieve internal pressure when exposed to fire. They should be UL or FM approved as well as OSHA approved. They make appear similar, but typical home gasoline storage cans are not the same and should not be used in laboratories.

Corrosive Storage Cabinets

Corrosive storage cabinets do not have specific regulatory requirements. They should be designed by the manufacturer to resist corrosion. Polyethylene cabinets are generally the most resistant, while steel cabinets will have a corrosion-resistant coating and oftentimes contain polyethylene liners. As an added benefit, some steel cabinets also meet the requirements of flammable storage cabinets, which may be necessary if you are storing flammable corrosives such as pyridine, triethylamine, or glacial acetic acid—always confirm this rating with the manufacturer. Wooden cabinets will generally resist corrosion (except for the metal hardware), but they should never be used for storing any oxidizing acids, such as nitric or perchloric acid.

Venting of corrosive cabinets may be beneficial if storing volatile corrosives such as hydrochloric acid, but it is not a requirement. Many cabinets below fume hoods have ventilation connections for this purpose. If you have questions about your existing cabinets, or if you would like additional information about corrosives storage, contact chemical safety.