tory hazards. To avoid formation of aerosols, dry sweeping should not be used in the laboratory. Remove broken glass, spilled chemicals, and paper litter from benchtops and laboratory chemical hoods.

   To avoid flooding, do not block the sink drains. Place rubber matting in the bottom of the sinks to prevent breakage of glassware and to avoid injuries.

   Do not pile up dirty glassware in the laboratory. Wash glassware carefully. Remember that dirty water can mask glassware fragments. Handle and store laboratory glassware with care. Discard cracked or chipped glassware promptly.

   Dispose of all waste chemicals properly and in accordance with organizational policies.

   Dispose of broken glass and in a specially labeled container for broken glass. Treat broken glassware contaminated with a hazardous substance as a hazardous substance.

   Dispose of sharps (e.g., needles and razor blades) in a specially labeled container for sharps. Treat sharps contaminated with a hazardous substance as hazardous substances.

Formal housekeeping and laboratory inspections should be conducted on a regular basis by the Chemical Hygiene Officer or a designee.

6.C.4 Transport of Chemicals

For more detailed information about transfer and transport of chemicals, see Chapter 5, section 5.F.

When transporting chemicals outside the laboratory or between stockrooms and laboratories, use only break-resistant secondary containment. Commercially available secondary containment is made of rubber, metal, or plastic, with carrying handle(s), and is large enough to hold the contents of the chemical containers in the event of breakage. Resealable plastic bags serve as adequate secondary containment for small samples.

When transporting cylinders of compressed gases, the cylinder must always be strapped in a cylinder cart and the valve protected with a cover cap. When cylinders must be transported between floors, passengers should not be in the elevator.

6.C.5 Storage of Chemicals

Avoid the accumulation of excess chemicals by acquiring the minimum quantities necessary for each procedure or research project. Properly label all chemical containers. Indicate any special hazards on the label. For certain classes of compounds (e.g., ethers as peroxide formers), write the date the container was opened on the label. For peroxide formers, write the test history and date of discard on the label as well.

Keep only small quantities (<1 L) of flammable liquids at workbenches. Larger quantities should be stored in approved storage cabinets. Store large containers (>1 L) below eye level on low shelves. Unless additional protection and secondary containment are provided, never store hazardous chemicals and waste on the floor. Be aware that fire codes dictate the total volume of flammable liquids, liquefied gases, and flammable compressed gases in a given work area. Ask your institution’s EHS expert for the fire code’s maximum flammable liquid and gas load for your laboratory, and ensure that your laboratory is in compliance with this code.

Refrigerators used for storage of significant quantities of flammable chemicals must be explosion-proof laboratory-safe units. Explosion-proof refrigerators are sold for this purpose and are labeled and hardwire installed. Such a refrigerator is mandatory for a renovated or new laboratory where flammable materials need refrigeration. Because of the expense of an explosion-proof refrigerator, a modified sparkproof refrigerator is sometimes found in older laboratories and laboratories using very small amounts of flammable materials. However, a modified sparkproof refrigerator cannot meet the standards of an explosion-proof refrigerator. Where they exist, a plan to phase out the sparkproof refrigerator is recommended.

Materials placed in refrigerators should be clearly labeled with water-resistant labels. Storage trays or secondary containment should be used to minimize the distribution of material in the event a container should leak or break. Retaining the shipping can for secondary containment is good practice. Regularly inspect storage trays, shipping cans, and secondary containment for primary container leaks and degradation. Laboratory refrigerators should have permanent labels warning against the storage of food and beverages for human consumption.

All chemicals should be stored with attention to incompatibilities so that if containers break in an accident, reactive materials do not mix and react violently.

(See Chapter 5, section 5.E, and Chapter 8, section 8.C.1.2, for more information.)

6.C.6 Use and Maintenance of Equipment and Glassware

Good equipment maintenance is essential for safe and efficient operations. Laboratory equipment should be regularly inspected, maintained, and serviced on schedules that are based on the manufacturer’s recom-

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