化学贮存: 分类、危害与兼容性

Safe laboratories require proper handling of hazardous chemicals, including appropriate labeling and storage.

Many types of chemicals are important for scientific research, thus it is crucial to know their properties and potential dangers. Chemicals may interact dangerously, and must be properly segregated and stored. Fire and safety organizations have strict standards for labeling, segregation, and storage, which can prevent hazards in the lab.

This video will illustrate how to evaluate, label, and store laboratory chemicals.

For identification and safety purposes, all chemicals must have labels with certain information. First, a product identifier shows the name and any alternatives of the chemical. A signal word indicates the level of hazard if one exists, and will either be ‘warning,’ for less severe hazards, or ‘danger,’ for more severe ones.

Further, the hazard statement describes the hazard, while the precautionary statements describe how to prevent risk, respond to exposure, and store and dispose the material. Hazard pictograms depict a specific type of hazard, like corrosion or aquatic toxicity. Lastly, contact information of the provider is shown.

Chemicals can additionally be labeled with the NFPA 704 diamond symbol. The blue quadrant contains the degree of health hazard, red the flammability hazard, yellow the reactivity hazard, and the white quadrant special hazards. Hazards are rated from 0, no hazard, to 4, severe risk. The special diamond may contain additional symbols indicating the type of hazard.

For detailed information about a chemical, read its associated 16-section Safety Data Sheet, or SDS. General information on a substance is found in section 1 through 3; its name and alternatives, hazard, and composition. Sections 4 through 6 provide emergency procedures in case of exposure, fire, or accidental release. Section 7 has information on handling and storage, and section 8 outlines protective equipment needed.

Sections 9 through 11 contain other important information about the substance-its physical and chemical properties, its stability and reactivity, and its toxicity. Sections 12 through 15 containing details about ecological impact, disposal considerations, transport requirements, and regulatory information, are not required to be in the SDS. Lastly, section 16 includes any other pertinent information about the substance.

After assessing their hazards, you should store chemicals with similar hazards together. Common hazard groups include acids, bases, flammables, oxidizers, toxics, peroxide-forming substances, pyrophoric-forming substances, water-reactive chemicals, and explosives. Each of these groups has specific storage requirements, which can prevent dangerous situations.

Additionally, some groups when mixed together form toxic fumes, or explosives. Therefore, they should be stored separately from each other, to prevent accidental spills from having disastrous consequences.

Now, we will show you how to evaluate hazards with a Safety Data Sheet, the use of NFPA 704 standard to label hazardous materials, and how to store specific types of chemicals in the laboratory.

First, assess a chemical’s potential hazards. Obtain the SDS when receiving or starting to work with a new chemical. If it is not packaged with the chemical or already available in the laboratory, it may be found on the provider’s website. Then, read this document carefully. Hazard information can be found in section 2, including a 704 diamond in some cases.

Additionally, section 9 may contain information on flammability hazards, section 10 on instability hazards, and section 11 on health hazards. Information on special hazards may be found in these sections or elsewhere in the document. Note that any special handling and storage instructions are found in section 7.

With the relevant hazard information from the SDS, fill in the NFPA diamond. If there are specific numbers from the SDS, use those, otherwise use the NFPA 704 guidelines to find what number to assign to each hazardous risk.

In this document, Table 5.2 has the criteria for health hazards, 6.2 for flammability hazards, 7.2 for instability hazards, and 8.2 for special hazards. With these numbers,fill in each hazard quadrant in the diamond and place on the chemical container.

Now that you have assessed and labeled the potential hazards of a material, you will need to store it properly. Always store chemicals according to instructions in the SDS, and separate out materials with incompatible chemical and physical characteristics. Make sure all caps are closed and properly fitted. Also, keep food and drink away from all storage areas.

For liquid storage use a chemically resistant secondary container in case there is a leak or spill. To avoid leaks dripping onto personnel, store these containers below shoulder height.

Specific chemical groups have different storage requirements. Store acids and bases separately, either in acid and base cabinets, or on protected non-metal shelves. Toxic chemicals should be stored in a cool, dry, and ventilated area. Date peroxide-forming chemicals on arrival and place in a dark, cool, and dry area. Dispose of them before the expected date of initial peroxide formation.

Pyrophoric-forming substances can ignite on contact with air and water, so purge them vigorously with inert gas. For more details on this procedure, watch our video on degassing liquids. Keep these chemicals away from flammables, oxidizers, and water, and store under inert atmosphere such as a glove box or glove bag.

Flammable and combustible chemicals require special care. Store these in approved storage cabinets, which are properly vented into a dedicated system. If they need to be refrigerated, use a laboratory-grade flammable-safe refrigerator. Keep this type of chemicals away from acids and bases, ignition sources, oxidizers, and corrosives.

Lastly, store explosives away from all other chemicals in a secure location, away from shock or friction. Take special care when handling explosive materials.

There are other groups of chemicals with additional storage considerations. Be sure to always check the SDS for any detailed storage instructions, and make sure the lab can handle storage of such materials.

You’ve just watched JoVE’s introduction to chemical labeling and storage. You should now understand the proper methods to indicate potential hazards, store chemicals, and prevent dangerous interactions. Thanks for watching!