A: Compatible Organic Bases
B: Compatible Pyrophoric & Water-Reactive Materials
Alkyl lithium solutions such as methyl lithium in tetrahydrofuran
Lithium aluminum hydride
C: Compatible Inorganic Bases
D: Compatible Organic Acids
E: Compatible Oxidizers Including Peroxides
F: Compatible Inorganic Acids not Including Oxidizers or Combustibles
Hydrogen fluoride solution
J: Poison Compressed Gases
K: Compatible Explosives or Other Highly Unstable Materials
Picric acid dry(<10% H2O)
L: Nonreactive Flammables and Combustibles, Including Solvents
X: Incompatible with ALL Other Storage Groups
Picric acid moist (10-40% H2O)
Sodium hydrogen sulfide
NOTE: A larger list of examples can be found on the CD that accompanies this book.
SOURCE: Adapted from Stanford University’s Chem Tracker Storage System. Used with permission from Lawrence M. Gibbs, Stanford University.
Some chemicals are regulated by federal agencies and require locked cabinets or storage in secure areas.
5.E.2 Storage According to Compatibility
It is prudent to store containers of incompatible chemicals separately. Separation of incompatibles will reduce the risk of mixing in case of accidental breakage, fire, earthquake, or response to a laboratory emergency. Even when containers are tightly closed, fugitive vapors can cause deleterious incompatibility reactions that degrade labels, shelves, cabinets, and containers themselves. As discussed in Chapter 4, a far more detailed review of incompatibilities needs to be done when chemicals are deliberately mixed,
Figure 5.1 (also available on the CD accompanying this book) and Table 5.1 show an example of a detailed classification system for the storage of groups of chemicals by compatibility. The system classifies chemicals into 11 storage groups. Each group should be separated by secondary containment (e.g., plastic trays) or, ideally, stored in its own storage cabinet. According to this system, it is most important to separate storage groups B (compatible pyrophoric and water-reactive chemicals) and X (incompatible with all other storage groups). These two groups merit their own storage cabinets. The accompanying compact disc includes a spreadsheet of hundreds of chemicals listed according to these storage groups.
There are other good classification systems for storing chemicals according to compatibility. At a minimum, always store fuels away from oxidizers. In other systems, the following chemical groups are kept separate by using secondary containment, cabinets, or distance: