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Lab Safety

Chemical Storage: Categories, Hazards And Compatibilities


Source: Robert M. Rioux & Taslima A. Zaman, Pennsylvania State University, University Park, PA

While the use of various chemicals in experimental research is essential, it is also important to safely store and maintain them as a part of the Environmental, Health and Safety (EHS) program. The properties of chemicals and their reactivity vary broadly and if chemicals are not managed, stored, and labeled properly, they can have harmful or even destructive consequences such as toxic fume production, fire or explosion, which may result in human fatality, property damage or environmental hazards. Therefore, an appropriate chemical label should identify the material and list the associated hazards, and users should have knowledge of how to read chemical labels and safety data sheets (SDS). Proper chemical storage must meet OSHA (Occupational Safety and Health Association) standards and this can prevent most chemical reactivity hazards.


Chemical storage begins with proper chemical labeling, which identifies the chemical and indicates what chemical hazards are associated to anyone who handles, uses, stores or transports. The National Fire Protection Association (NFPA) diamond symbol rates the degree of health (blue), flammability (red), reactivity (yellow), and special hazards (white) of chemicals. Hazards are rated from zero for no hazard to 4 for severe risk. Chemicals must then be segregated according to their chemical family or hazard classification, and stored appropriately so that any incompatibility is avoided. SDS are detailed documents which cover more topics relevant to safety than labels, and therefore SDS should be consulted to ensure thoroughly safe handling of hazardous chemicals.


1. Labeling for Hazardous Material

  1. Collect information on hazards from applicable sections of the safety data sheet (SDS) for the chemical. Some SDSs may even provide the NFPA 704 diamond symbol with hazard rating numbers filled in already.
  2. If the SDS does not provide a NFPA diamond label for the chemical, the information may be obtained under the following sections of the SDS:
    • Health hazard information under Section 11
    • Flammability information under Section 9
    • Instability information under Section 10
    • Special information under Section 9, 10, 11
    Check other sections of the SDS for additional information.
  3. Compare the SDS criteria with the current edition copy of NFPA 704 criteria shown in:
    • Table 5.2 Degrees of Health Hazards
    • Table 6.2 Degrees of Flammability Hazards
    • Table 7.2 Degrees of Instability Hazards
    • Table 8.2 Degrees of Special Hazards
  4. Once the numbers for the degree of hazard associated with the criteria are determined, place in the correct quadrant of NFPA 704 placard.
  5. The Hazard Communication Standard, 29 CFR 1910.1200 requires all manufacturers, importers, and distributers of hazardous materials to label chemicals with the following information: product identifier, signal word, hazard statement(s), precautionary statement(s) and pictogram(s), and name, address and telephone number of the material manufacturer, importer or distributer.
  6. The product identifier can include the name and alternate names of the material, a code, such as the CAS number, and the product batch number.
  7. The signal word is to indicate the level of the hazard and can only be 'warning' or 'danger'. 'Warning' means less severe, 'danger' means more severe.
  8. A hazard statement describes the hazard of the material. Hazard statements are always written the same for a given hazard, for example, 'May cause allergy or asthma symptoms or breathing difficulties if inhaled'. The only acceptable alterations to hazard statements are if multiple hazard statements are combined to improve readability.
  9. There are four types of precautionary statements: prevention, response, storage, and disposal. A prevention precautionary statement is aimed at minimizing risk, for example, 'handle under inert gas'. A response precautionary state is included in the case of a spill or exposure to the material, for example, 'take off immediately all contaminated clothing'. An example of a storage precautionary statement is 'protect from sunlight'. An example of a disposal precautionary statement is 'dispose of contents/container to comply with applicable local, national and international regulation.'

2. Segregate Incompatible Chemicals

  1. Chemicals should always be segregated and stored according to their incompatible chemical and physical characteristics. Basic hazard groups include:
    1. Acids
    2. Bases
    3. Flammables
    4. Oxidizers
    5. Toxics
    6. Peroxide forming chemicals
    7. Pyrophoric forming substances
    8. Water reactive chemicals
    9. Explosives
  2. Below are some common hazard groups to segregate:
    1. No acids with bases
    2. No bases with acids
    3. No acids or bases with flammables
    4. No oxidizers near compressed flammable gases
  3. Incompatible chemicals must not be stored in close proximity to each other. In an emergency situation of a fire, earthquake or a spill, incompatible chemicals could mix and react to cause toxic fume production or an explosion.

3. Chemical Storage Method

  1. Chemicals should be stored according to their incompatible chemical and physical characteristics. Alphabetical storage may be used within a compatible chemical group but never as a chemical storage plan for an entire inventory.
  2. Chemicals must be stored in accordance to the manufacturer's directions or SDS instructions.
  3. Liquid chemicals should not be stored over shoulder height to ensure easy access and handling and be stored in chemically resistant secondary containers in case there is a leak or spill.
  4. Chemicals containers should be stored with closed and properly fitted caps.
  5. Acids and bases should be stored separately and stored in acid cabinets or on protected shelves which are not metal in order to avoid corrosion
  6. Flammable and combustible chemicals must be stored in approved flammable storage cabinets and kept away from any ignition source, oxidizers, or corrosives. Flammable storage cabinets should be properly vented into the building's dedicated vent system. Laboratory-grade flammable-safe refrigerators should be used when flammable chemicals require refrigeration. Do not store food or beverages in the laboratory refrigerator.
  7. Toxic chemicals should be stored in a ventilated, cool, and dry area.
  8. Peroxide forming chemicals must be dated upon delivery and opening, and must be disposed before the expected date of initial peroxide formation and be stored in a dark, cool, and dry area.
  9. Air and water must be removed rigorously from containers of pyrophoric forming substances and should be stored away from flammables in a cool and dry area.
  10. Explosives should be stored away from all other chemicals in a secure location and away from shock or friction.

4. Safety Data Sheets

Note: The purpose of the SDS is to provide an easy to understand, standardized document that informs the user of important information regarding the material. OSHA requires manufacturers, distributors, and importers to provide SDSs to end-users of hazardous materials (Hazard Communication Standard 29 CFR 1910.1200(g)). The SDS is a 16 section document containing details on properties, hazards, storage and transport, regulatory status, protective measures, and emergency procedures. The following is an outline of the 16 sections in an SDS.

  1. Section 1: Identification: This section provides the name and alternate names of the material along with suggested uses, restrictions and contact information of the supplier.
  2. Section 2: Hazard identification: Hazards associated with the material are identified in this section. Hazard symbols may be shown along with a description of the hazard.
  3. Section 3: Composition/information on ingredients: For substances, this sections contains the chemical name, alternative names and identifiers, CAS number, impurities and additives. For mixtures, the same information for substances is provided for all components of the mixture. The percentage of each component is specified, except in the case of trade secrets. If chemical composition has been withheld due to trade secret, this must be stated. Toxicology data is provided for each hazardous substance in the material (lethal dose/lethal concentration, etc).
  4. Section 4: First-aid measures: In the event of exposure (skin and eye contact, inhalation, or ingestion) to the material, this section states the first response procedures for untrained personnel. The effects, acute and delayed, are detailed.
  5. Section 5: Fire-fighting measures: Appropriate and inappropriate extinguishing equipment, and recommended protective firefighting equipment is stated. Hazardous combustion products are listed.
  6. Section 6: Accidental release measures: Procedures and methods for handling spills and leaks are outlined in this section. Personal precautions, emergency procedures containment methods and cleanup procedures are covered.
  7. Section 7: Handling and storage: This section provides information on safe handling and storage of the material. Safe handling and storage conditions are outlined, including incompatibilities and hygiene practices.
  8. Section 8: Exposure controls/personal protection: This section outlines exposure limits and engineering controls (e.g., ventilation system, glove box) and PPE (e.g., glove type, apron, face protection) that can be used to prevent exposure to the material.
  9. Section 9: Physical and chemical properties: This section contains information regarding the physical and chemical properties of the material. The minimum information this section must require is state (gas, liquid, solid), color, odor, odor threshold, melting point, boiling point, density, vapor density, viscosity, vapor pressure, evaporation rate, pH, upper and lower flammability limits, upper and lower explosive limits, auto-ignition temperature, flash point, flammability, decomposition temperature, octanol-water partition coefficient, and solubility.
  10. Section 10: Stability and reactivity: This section provides information on the reactivity of the material under specific conditions, incompatibilities and conditions that should be avoided.
  11. Section 11: Toxicological information: This section contains information on the toxicology and health effects of the material. This includes effects and symptoms of acute and chronic exposure, routes of exposure (skin and eye contact, inhalation, or ingestion) and LD50/LC50 data. LD50/LC50 (lethal dose, 50%/lethal concentration, 50%) is the dose/concentration required to kill 50% of the exposed population in a set time frame.
  12. Section 12: Ecological information: (non-mandatory) This section includes information on the environmental impact of the material. If available, data on aquatic and terrestrial organisms should be provided.
  13. Section 13: Disposal considerations (non-mandatory): This section contains information on appropriate disposal of the material and items contaminated with the material, including appropriate containers and methods.
  14. Section 14: Transport information (non-mandatory): This section outlines the transportation and shipping requirements of the material. Information includes the UN number, UN shipping name, transport hazard class, packing group number, relevant environmental hazards and any material specific instructions.
  15. Section 15: Regulatory information (non-mandatory): This section details any regulatory information regarding the material or components of the material.
  16. Section 16: Other information: This section notes when the SDS was last revised and any changes since the first revision.

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!


RGN Reactivity Group Incompatible With RGN:
1 Acids, Mineral, Non-Oxidizing 4-15,17-26,28,30-34,101-107
2 Acids, Mineral, Oxidizing 3-34,101-103,105-107
3 Acids, Organic 2,4,5,7,8,10-12,15,18,21,22,24,265,33,34, 102-105,107
4 Alcohols and Glycols 1-3,8,18,21,25,30,34,104,105,107
5 Aldehydes 1-3,7,8,10,12,21,25,27,28,30,33,34,104,105, 107
6 Amides 1,2,21,24,104,105,107
7 Amines, Aliphatic and Aromatic 1-3,5,12,17,18,21,24,30,34,104,105, 107
8 Azo Compounds, Diazo Compounds and Hydrazines 1-5,9,11-13,17-23,25,30-34, 102-107
9 Carbamates 1,2,8,10,21,22,25,30,104, 107
10 Caustics 1-3,5,9,13,17-19,21,22,24-27,32,34,102,103, 107
11 Cyanides 1-3,5,9,13,17-19,21,22,24-27,32,34,102,103, 107
12 Dithiocarbamates 1-3,8,17-19,21,25,30,34,103,104, 107
13 Esters 1,2,8,10,21,25,102,104,105, 107
14 Ethers 1,2,104, 107
15 Fluorides, Inorganic 1-3, 107
16 Hydrocarbons, Aromatic 2,104, 107
17 Halogenated Organics 1,2,7,8,10,11,20-23,25,30,104,105, 107
18 Isocyanates 1-4,7,8,10-12,20-22,25,30,31,33, 104-107
19 Ketones 1,2,8,10,11,20,21,25,30,104,105, 107
20 Mercaptons and Other Organic Sulfides 1,2,8,17-19,21,22,25,30,34,104,105, 107
21 Metals, Alkali and Alkaline Earth Elemental 1-13,17-20,25-27,30-32,34,101-104,106, 107
22 Metals, Other Elemental and Alloys as Powders, Vapors or Sponges 1-3,8-10,17,18,20,28,30,34,102-104,106, 107
23 Metals, Other Elemental and Alloys as Sheets, Rods, Drops, Moldings 1,2,8,17,102-104, 107
24 Metal and Metal Compounds, Toxic 1-3,6,7,10,26,30,34,102,103,106, 107
25 Nitrides 1-5,8-13,17-21,26-27,30,31,34,101-104,106, 107
26 Nitrites 1-3,10,21,24,25,30,104,105, 107
27 Nitro Compounds, Organic 2,5,10,21,25,104,105, 107
28 Hydrocarcons, Aliphatic, Unsaturated 1,2,5,22,30,104, 107
29 Hydrocarbons, Aliphatic, Saturated 2,104, 107
30 Peroxides and Hydroperoxides, Organic 1,2,4,5,7-9,11,12,17-22,24-26,28,31-34,101-105, 107
31 Phenols and Cresols 1,2,8,18,21,25,30,34,102-105, 107
32 Organophosphates, Phosphothioates, Phosphodithioates 1,2,8,10,21,30,34,104,105, 107
33 Sulfides, Inorganic 1-3,5,8,18,30,34,102-104,106, 107
34 Epoxides 1-5,7,8,10-12,20-22,24,25,30-33,102,104,105, 107
101 Combustible and Flammable Materials, Misc. 1,2,21,25,30,102,104,105, 107
102 Explosives 1-3,8,10,13,21-25,30,31,33,34,101,105-105, 107
103 Polymerizable Compounds 1-3,8,10-12,21-25,30,31,33,102,104,105, 107
104 Oxidizing Agents, Strong 1,3-9,11-14,16-23,25-34,101-103,105, 107
105 Reducing Agents, Strong 1-8,12,13,17-20,26,27,30,31,32,34,101-104,106, 107
106 Water and Mixtures Containing Water 1,2,8,18,21,22,24,25,33,105, 107
107 Water Reactive Substances ALL!

Table 1. Chemical compatibility chart. Obtained from Penn State Environmental Health and Safety website at http://legacy.ehs.psu.edu/hazmat/chemical_compatibility.cfm

Applications and Summary

Research laboratories often contain many chemicals that may pose distinct hazards to our health and well-being. Proper storage, maintenance, and labeling of these chemicals can help prevent accidents and provide a safe working environment. While the list of chemicals may vary by laboratory and experiments, this document provides a basic guideline to storing and maintaining chemicals, and using the SDS to properly handle chemicals. Specific hazard assessment may reveal more specialized and additional storage requirements.


  1. Quick Card National Fire Protection Association at http://www.nfpa.org/Assets/files/AboutTheCodes/704/NFPA704_HC2012_QCard.pdf
  2. Occupational Health and Safety (OSHA) Brief on Hazard Communication Standard: Labels and Pictograms, 29 CFR 1910.1200 (HCS) at https://www.osha.gov/Publications/OSHA3636.pdf
  3. Occupational Health and Safety (OSHA) Regulations (Standards - 29 CFR) 1926.152 - Flammable liquids at https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10673#1926.152(a)
  4. NFPA 30: Flammable and Combustible Liquids Code at http://www.nfpa.org/codes-and-standards/all-codes-and-standards/list-of-codes-and-standards?mode=code&code=30
  5. Occupational Health and Safety (OSHA) National Research Council Recommendations Concerning Chemical Hygiene in Laboratories Standard-1910.1450 App A at https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10107
  6. OSHA, Hazard Communication Standard, 29 CFR 1910.1200, 2012
  7. Globally Harmonized System of Classification and Labelling of Chemicals (Second revised ed.), New York and Geneva: United Nations, 2007, ISBN 978-92-1-116957-7, ST/SG/AC.10/30/Rev.2 ("GHS Rev.2")
Chemical Storage: Categories, Hazards And Compatibilities
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