At a recent American Society of Safety Engineers meeting, Matt Bruns of Pfizer Research Corp. gave a presentation on establishing a consistent program for safe chemical storage.
Under Brun's chemical categorization, segregation, and storage protocol, chemicals are segregated into seven storage categories in which chemicals are grouped from most hazardous to less hazardous. The protocol was designed to manage thousands of chemicals, but is a most useful guide for any size company to avoid injuries or damage caused by reactions of incompatible chemicals stored together.
The seven storage groups are:
- Water-reactive, pyrophoric, self-reactive—such as lithium aluminum hydride, butyl lithium, potassium cyanide, and sodium azide. Does not include acidic water-reactive chemicals.
Flammable chemicals—such as ethanol, methanol, hexane, toluene, and tetrahydrofuran. Includes combustible liquids with a flashpoint below 140º F.
- Store in secure, sealed secondary container in a dry location, e.g., a dry box or desiccator
- Isolate from other groups
- Separate from aqueous solutions and protect from water
- In refrigerator: double-contain in bins or plastic bags
Liquid and solid oxidizers—such as 30 percent hydrogen peroxide, sodium dichromate, potassium permanganate, and sodium periodate.
- Store in flammable safety cabinet (a secondary container) or in a lab-safe refrigerator
- Groups 5 and 6 may be stored with this group within a flammable storage cabinet
Liquid and solid acids/corrosives—such as sulfuric acid, trifluoroacetic acid, glacial acidic acid, and nitric acid.
- Cannot be stored with Groups 1, 2, 4, 5, or 6
- Store by itself in a dedicated metal cabinet or desiccator
- May be stored within a secondary container in lab cabinet or on lab shelf segregated from Group 7
- Store double contained in refrigerator segregated from other groups
- Large quantities of oxidizers (>3 kilograms) must be kept separate from all other chemicals in a dedicated cabinet
Liquid and solid bases/corrosives—such as ammonium hydroxide, sodium hydroxide (includes pellets), and potassium hydroxide.
- Store within secondary containment in a cabinet dedicated to acid storage (not with bases)-use secondary storage as spill control
- Use additional secondary containment for oxidizing acids and hydrofluoric acids
- Separate mineral acids from organic acids
- Not all acids are in Group 4 (benzoic acid is in Group 7)
- Aqueous solutions of 2 M concentration and less are exempted and maybe store with Group 7 on lab shelves
Nonflammable solvents and other regulated chemicals—such as chloroform, methylene chloride, N-methylpyrollidinone, and dimethylformamide.
- Store within secondary containment in a cabinet dedicated to bases (never with acids)—use secondary containment as spill control
- May be stored in a flammable storage cabinet with Group 2 and/or Group 6-keep separate using secondary containment
- Group does not include carbonates, triphosphates, or fluorides—weak bases are not corrosive, e.g., potassium carbonate is Group 7
- Aqueous solutions of 2 M concentration and less are exempted and maybe store with Group 7
Low hazard solid and liquids—such as Calcium chloride, copper sulfate, MgSO4, Potassium carbonate, Boric acid, and PF compounds and intermediates.
- Group contains nonflammable liquids and Class III combustible organics having a flashpoint at or above 140º F, and other regulated chemicals, including carcinogens, mutagens, and teratogens
- Store in sealed, secure, secondary containers
- Store in cabinets—if stored on shelves and in cabinets, secondary containment is required to contain spills
- May be stored within a flammable liquid storage cabinet with Group 2 and Group 5
- Group also includes dilute aqueous acids and bases ( less than or equal to 2 M) and other aqueous solutions
- Store in cabinets or on open shelves—use secondary containment to control spills
- Segregate PF compounds and intermediates—store in boxes or bins
- Store dry solids above liquids
According to Bruns, workers and supervisors in work areas with many chemicals may be tempted to store their chemicals alphabetically, according to common chemical name to make it easy to find them, but this is a dangerous practice. It is safer to take the time to create a seven category group storage system. Then you can store them alphabetically within the specific group.