ment. The laboratory director assigns responsibility for keeping these units safe, clean, and organized and monitors their proper operation. Extra care is required because frost and condensation not only obscure labels but also make containers hard to hold and easy to drop. Too often, research materials are stored haphazardly in cold storage areas. To ensure safety:
• Use chemical storage refrigerators only for storing chemicals.
• Use waterproof tape and markers to label laboratory refrigerators and freezers with the following:
NO FOOD—LAB CHEMICAL STORAGE ONLY
• Do not store flammable liquids in a refrigerator unless it is approved for such storage. Such refrigerators are designed not to spark inside the refrigerator. If refrigerated storage is needed inside a flammable-storage room, it is advisable to choose an explosion-proof refrigerator. Do not store oxidizers or highly reactive materials in the same unit as flammables.
• All containers must be closed and stable to reduce the risk of a spill. Round-bottom flasks need secondary containment.
• Label all materials in the refrigerator with contents, owner, date of acquisition or preparation, and nature of any potential hazard.
• Organize contents by owner but keep incompatibles separate. Organize by labeling shelves and posting the organization scheme on the outside of the unit.
• Secondary containment, such as plastic trays, is highly recommended for all containers. Secondary containment captures spills and leaks and facilitates organization and labeling.
• Every year, review the entire contents of each cold storage unit. Dispose of all unlabeled, unknown, or unwanted materials.
• When any trained laboratory personnel leaves, review the contents of each cold storage unit to identify that person’s material, so that it can be disposed of or reassigned.
5.E.5 Storing Flammable and Combustible Liquids
NFPA Standard 45 (NFPA, 2004) limits the quantity of flammable and combustible liquids in laboratories. (International, state, and local building codes and regulations should also be consulted.) The quantity allowed depends on a number of factors, including
• construction of the laboratory,
• number of fire control zones in the building,
• floor level where the laboratory is located,
• fire protection systems built into the laboratory,
• storage of flammable liquids in flammable-liquid storage cabinets or safety cans, and
• type of laboratory (i.e., instructional or research and development).
Many laboratories have a business (B) classification with sprinkler systems and a flammable and combustible liquid storage limitation, as shown in Table 5.2. Note that laboratory unit fire hazard classes are based on the quantities of flammable and combustible liquids in the space. This classification significantly affects the fire separation requirements for the laboratory. Most research laboratories fall under Class B, C, or D.
Note that some laboratories may be in jurisdictions that refer to the International Code Agency rather than NFPA, and state and local regulations may be more stringent than those cited here. Laboratory personnel and organization should be sure to check the requirements specific to their area.
The container size for storing flammable and combustible liquids is limited both by NFPA Standards 30 and 45 and by the Occupational Safety and Health Administration (OSHA). Limitations are based on the type of container and the flammability of the liquid, as shown in Table 5.3.
Label all chemical containers with the identity of the contents and hazard warning information. All chemical waste containers must have appropriate waste labels. Flammable liquids that are not stored in safety cans should be placed in storage cabinets rated for flammable storage. When space allows, store combustible liquids in flammable-storage cabinets. Otherwise, store combustible liquids in their original containers. Store 55-gal drums of flammable and combustible liquids in special storage rooms for flammable liquids. Keep flammable and combustible liquids away from strong oxidizing agents, such as nitric or chromic acid, permanganates, chlorates, perchlorates, and peroxides. Keep flammable and combustible liquids away from any ignition sources. Remember that many flammable vapors are heavier than air and can travel to ignition sources. Take the following additional precautions when storing flammable liquids:
• When possible, store quantities of flammable liquids greater than 1 L (approximately 1 qt, or 32 oz) in safety cans. Refer to Table 5.3.
• Store combustible liquids either in their original (or other NFPA- and DOT-approved) containers or in safety cans. Refer to Table 5.3.