9.0 Proper Chemical Storage

9.1       General Rules and Principles of Safe Chemical Storage

The primary purpose of this plan is to control health or physical hazards posed by chemical compounds during storage in the lab. Specifically, it is designed to:

1. Protect flammables from ignition;

2. Minimize the potential of exposure to poisons; and

3. Segregate incompatible compounds to prevent their accidental mixing.

9.1.1     A Designated Storage Place for Each Compound

Do not store stock supplies of chemicals on benchtops where they are unprotected from ignition sources and are more easily knocked over. Only chemicals in use or of low hazard levels (e.g., salts and buffers) are permitted on benchtops.

9.1.2     Do Not Store in Chemical Fume Hood

9.1.3     Seal All Chemical Containers                                                      

9.1.4     Alphabetical Only within Storage Groups

9.1.5     Away from Sun and Heat

9.1.6     Do Not Store Chemicals Under the Sink

9.1.7     Label Chemicals Properly

All containers within the lab must be labeled according to the instructions in Section 5.1,Labels and Labeling. Suspect and known carcinogens must be labeled as such and segregated within trays to contain leaks and spills; see Section 12.11, Select Carcinogens, Suspect Carcinogens, Investigational Drugs, and Hazardous Drugs.

9.1.8     Safeguard Against Theft

9.1.9     Liquid Chemicals

Storage of liquid chemicals is more hazardous than storage of solids and is subject to numerous and varied storage requirements.

9.2       Chemical Storage Groups

In this plan, there are nine storage groups. Seven of these groups cover storage of liquids based on the variety of hazards posed by these chemicals. Specific instructions must be followed for metal hydrides (Group 8) and certain individual compounds, but otherwise, all dry solids are in Group 9.

9.2.1     How to Determine the Correct Storage Group for a Chemical

Section 13, Chemical Index, gives the correct storage group as well as other important information for each chemical listed. If a chemical in question is not listed in the index, determine the correct storage group by the hazard information on the container label, MSDS, or call EH&S.

9.2.2     Multi-Hazard Liquids

9.2.3     Ranking Chemical Storage Groups: From Most Hazardous to Least Hazardous

• Group 1: Flammables

• Group 2: Volatile Poisons

• Group 3: Oxidizing Acids

• Group 4: Organic and Mineral Acids

• Group 5: Liquid Bases

• Group 6: Liquid Oxidizers

• Group 7: Non-Volatile Poisons

• Group 8: Metal Hydrides

• Group 9: Dry Solids

9.3       Storage Group Definitions

9.3.1     Group 1: Flammable Liquids

Includes liquids with flashpoints < 100°F. Examples include all alcohols, acetone, acetaldehyde, acetonitrile, amyl acetate, benzene, cyclohexane, dimethyldichlorosilane, dioxane, ether, ethyl acetate, histoclad, hexane, hydrazine, methyl butane, picolene, piperidine, propanol, pyridine, some scintillation liquids, all silanes, tetrahydrofuran, toluene, triethylamine, and xylene.

Primary Storage Concern: Protect flammable liquids from ignition.

Acceptable Storage Facilities/Methods:

• Store in a flammable cabinet, or
• Store in a flammable-storage refrigerator/freezer.

Compatible Storage Groups: Flammables may be with either Group 2: Volatile Poisons, or Group 5: Liquid Bases, but not with both.

9.3.2     Group 2: Volatile Poisons

Includes poisons, toxics, and select and suspected carcinogens with strong odor or an evaporation rate greater than 1 (butyl acetate = 1). Examples include carbon tetrachloride, chloroform, dimethylformamide, dimethyl sulfate, formamide, formaldehyde, halothane, mercaptoethanol, methylene chloride, and phenol.

Primary Storage Concern: Prevent volatile poison inhalation exposures.

Acceptable Storage Facilities/Methods:

• Store in a flammable cabinet; or
• Store containers of less than one liter in a refrigerator.

Compatible Storage Groups: Volatile poisons may be stored with flammables if bases are not present.

9.3.3     Group 3: Oxidizing Acids

All oxidizing acids are highly reactive with most substances and each other. Examples include nitric, sulfuric, perchloric, phosphoric, and chromic acids.

Primary Storage Concern: Prevent contact and reaction between oxidizing acids and other substances and prevent corrosive action on surfaces.

Acceptable Storage Facilities/Methods:

• Store in a safety cabinet.
• Each oxidizing acid must be double-contained (i.e., the primary container must be kept inside a canister, tray or tub).

Compatible Storage Groups: Oxidizing acids must be double-contained and should be segregated in their own compartment in a safety cabinet. When quantities are small (e.g., 1 or 2 bottles) they do not warrant a separate compartment. Small quantities may be double-contained and stored with Group 4: Organic and Mineral Acids. Store oxidizing acids on the bottom shelf, below Group 4.

9.3.4     Group 4: Organic and Mineral Acids                           

Organic and mineral acids. Examples include acetic, butyric, formic, glacial acetic, hydrochloric, isobutyric, mercaptoproprionic, proprionic, and trifluoroacetic acids.

Primary Storage Concern: Prevent contact and reaction with bases and oxidizing acids and prevent corrosive action on surfaces.

Acceptable Storage Facilities/Methods:

• Store in a safety cabinet.

Compatible Storage Groups: Small amounts of double-contained oxidizing acids can be stored in the same compartment with organic acids if the oxidizing acids are stored on the bottom shelf.

Exceptions: Acetic anhydride and trichloroacetic anhydride are corrosive. These acids are very reactive with other acids and shouldnot be stored in this group. It is better to store them with organic compounds in Group 7: Non-Volatile Liquid Poisons. See Section 12.9, Reactives.

9.3.5     Group 5: Liquid Bases

Liquid bases. Examples include sodium hydroxide, ammonium hydroxide, calcium hydroxide, and gluteraldehyde.

Primary Storage Concern: Prevent contact and reaction with acids.

Acceptable Storage Facilities/Methods:

• In a safety cabinet; or
• In tubs or trays in normal cabinet.

Compatible Storage Groups: Liquid bases may be stored with flammables in the flammable cabinet if volatile poisons are not stored there.

9.3.6     Group 6: Liquid Oxidizers

Oxidizing liquids react with everything, potentially causing explosions or corrosion of surfaces. Examples include ammonium persulfate and hydrogen peroxide (if greater than or equal to 30%).

Primary Storage Concern: Isolate liquid oxidizers from other substances.

Acceptable Storage Facilities/Methods:

• Total quantities exceeding three liters must be kept in a cabinet housing no other chemicals.
• Smaller quantities must be double-contained when stored near other chemicals (e.g., in a refrigerator).

Compatible Storage Groups: There are no compatible storage groups for liquid oxidizers; store liquid oxidizers separately from other chemicals.

9.3.7     Group 7: Non-Volatile Liquid Poisons

Includes highly toxic (LD₅₀ oral rat < 50 mg/kg) and toxic chemicals (LD₅₀ oral rat < 500 mg/kg), select carcinogens, suspected carcinogens, and mutagens. Examples include acrylamide solutions, Coomassie blue stain, diethylpyrocarbonate, diisopropyl fluorophosphate, uncured epoxy resins, ethidium bromide, and triethanolamine.

Primary Storage Concern: Prevent contact and reaction between non-volatile liquid poisons and other substances.

Acceptable Storage Facilities/Methods:

• Store in a cabinet or refrigerator (i.e., non-volatile liquid poisons must be enclosed).
• Do not store on open shelves in the lab or cold room.
• Liquid poisons in containers larger than one liter must be stored below bench level on shelves closest to the floor. Smaller containers of liquid poison can be stored above bench level only if behind sliding (non-swinging) doors.

Compatible Storage Group: Store non-volatile liquid poisons with non-hazardous liquids (e.g., buffer solutions).

Exceptions: Anhydrides (e.g., acetic and trichloroacetic) are organic acids; however, it is better to store them with this group, since they are highly reactive with other acids.

9.3.8     Group 8: Metal Hydrides

Most metal hydrides react violently with water, some ignite spontaneously in air (pyrophoric).Examples include sodium borohydride, calcium hydride, and lithium aluminum hydride.

Primary Storage Concern: Prevent contact and reaction with liquids and, in some cases, air.

Acceptable Storage Facilities/Methods:

• Store using secure, waterproof double-containment according to label instructions.
• Isolate from other storage groups.

Compatible Storage Groups: If securely double-contained to prevent contact with water or air, metal hydrides may be stored in the same area as Group 9: Dry Solids.

9.3.9     Group 9: Dry Solids

Includes all powders, hazardous and non-hazardous. Examples include benzidine, cyanogen bromide, ethylmaleimide, oxalic acid, potassium cyanide, and sodium cyanide.

Primary Storage Concern: Prevent contact and potential reaction with liquids.

Acceptable Storage Facilities/Methods:

• Cabinets are recommended, but if not available, open shelves are acceptable.
• Store above liquids.
• Warning labels on highly toxic powders should be inspected and highlighted or amended to stand out against less toxic substances in this group.
• It is recommended that the most hazardous substances in this group be segregated.
• It is particularly important to keep liquid poisons below cyanide-containing or sulfide-containing poisons (solids); a spill of aqueous liquid onto cyanide-containing or sulfide-containing poisons would cause a reaction that would release poisonous gas.

Compatible Storage Groups: Metal hydrides, if properly double-contained, may be stored in the same area as dry solids.

Exceptions: Solid picric or picric sulfonic acid can be stored with this group, but should be checked regularly for dryness. When completely dry, picric acid is explosive and may detonate upon shock or friction. See detailed chemical safety information on picric acid at the EH&S website, which includes updated, detailed information on laboratory chemicals. You’ll find the site at:

centernet.fhcrc.org/CN/depts/ehs/chemical/

9.4       Storage Plan Variations for Different Lab Facilities

Below are illustrations of possible chemical storage arrangements for two types of lab facilities. They are provided merely as examples of arrangements that satisfy the requirements of the chemical storage plan. They are not intended to restrict storage to the particular arrangements and facilities depicted. Refer to Section 9.3, Storage Group Definitions, for segregation and facility requirements.

Figure III. 3: Variation 1: Chemical Storage Plan for Lab with Freestanding Acid Cabinet

Figure III. 4: Variation 2: Chemical Storage Plan for Standard Labs