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Flammable and combustible liquids in laboratories
Use the following guidelines for storing flammable and combustible chemicals in the laboratory. (Information from Chemical Safety and Disposal Guide, University of Wisconsin-Madison, 2005):
- Minimize the amount of flammable liquids in your lab. Buy only what you will use in the immediate future, and buy the smallest size that you need. Excess flammable solvents risk a fire, a dangerous spill and, if you are exposed to them, your health. Unused surpluses create an unnecessary disposal cost for the University.
- If a building or departmental flammable solvent storage room with a fire suppression system is available, store flammable materials there until you need to use them and remove only the amount needed for a particular experiment or task.
- In the laboratory, store flammables in a UL-approved (or equivalent) flammable storage cabinet. Unless a cabinet is marked as approved for storage of flammable liquids, flammable solvents may not be stored there. In general, do not store flammable liquids in cabinets below fume hoods or sinks.
- Store flammables, combustibles and other fuels away from strong oxidizers, such as perchloric and nitric acids. It is best to store flammable liquids in an approved storage cabinet dedicated solely for that purpose.
- Limit quantities of flammable liquids stored outside of safety cans and flammable storage cabinets to less than ten gallons per one hundred square feet (i.e., per lab suite). If you include flammables stored in safety cans and flammable storage cabinets, limit the amount of flammable liquids to less than twenty gallons per one hundred square feet of lab space. Thus, the maximum quantity of flammable liquids in each lab suite / fire area depends upon the storage configuration:
- Glass, metal or plastic 10 gallons (38 liters)
- Safety cans 25 gallons (95 liters)
- Flammable liquid storage cabinets 180 gallons (684 liters)
- On your benchtop, limit the storage of flammable liquids to those in immediate use. Handle flammable chemicals in areas free from ignition sources.
- It is best to store bottles of flammable liquids in a tray or pan (secondary containment) to catch any spills.
- Use plastic trays when storing chemicals in freezers. This prevents the bottles from becoming embedded in ice and frost that often forms in freezers. It also contains spills and drips.
- Always bond metal containers to metal receivers when transferring large volumes of flammable liquids or gases.
- Static electricity can ignite flammable gases or vapors. If static electricity is a problem, minimize static electricity by spraying with an antistatic agent. Use nonconductive materials (floors, mats, etc.) and grounding straps on instruments and machines, especially when transferring flammable chemicals between metal containers. These reduce the risk of generating static sparks. The greatest hazard from static electricity is in the winter when the air is dry.
- Never heat flammable chemicals with an open flame, use a water bath, oil bath, heating mantle, hot air bath, etc.
- Use a fume hood when there is a possibility of dangerous vapors.
- Cold rooms pose a unique set of problems. One big problem with anything stored in a walk-in cold room is that outside (hallway or room) air brings in moisture which condenses on everything that is cold. This will lead to mold which thrives on paper and glue of labels and can make stored containers "unknowns."
Take precautions when storing flammable chemicals in a refrigerator. Refrigerator temperatures are almost always higher than the flash points of flammable liquids (see 2.1.a). Compressors and circuits are often located at the bottom of the refrigerator where vapors from small spills or leaks can accumulate. Electrical sparks from a conventional refrigerator can then ignite the flammable vapors that build up inside. Unless a cold room is ventilated and has a fire suppression sprinkler system, do not store flammable liquids there. Two kinds of refrigerators are approved for storage of flammables:
- Flammable liquid storage refrigerators. These have no spark sources within the refrigerator cabinet. There are, however, spark sources outside the refrigerator cabinet from switches, motors, relays, etc. These spark sources can ignite flammable vapors present outside of the refrigerator. A bottle of flammable liquid that drops and breaks near one of these refrigerators can easily be ignited by the sparks.
- Explosion-proof refrigerators. These refrigerators are considerably more expensive because they have all spark sources completely sealed inside and are safe for flammable atmospheres both within and outside of the refrigerator cabinet.
Conventional refrigerators in laboratories and cold rooms are not safe for flammable storage and must be labeled "NO FLAMMABLES".
Regulations, interpretations and standards
- 29 CFR 1910.106 – Flammable and combustible liquids (general industry)
- 29 CFR 926.152 – Flammable and combustible liquids (construction)
Wisconsin Department of Safety and Professional Services
The Wisconsin Department of Safety and Professional Services (DSPS) adopted OSHA’s general industry and construction standards as the rule for public employees in Wisconsin. No modifications or amendments have been adopted to the standards cited above. Two modifications in related areas were adopted:
- SPS 332.24 – To the extent that ventilation is used when working with flammable liquids, there are additional rules in place for the workplace ventilation rules at 29 CFR 1910.94.
- SPS 332.26 – There is a plan submittal requirement for spray finishing using flammable and combustible materials that is an addition to the rules in CFR 1910.107.
- NFPA 30, Flammable and Combustible Liquids Code (about NFPA 30)
- NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals (about NFPA 45)
- Does NFPA 30 govern storage of liquids in a laboratory? In the open work area of the laboratory, no. The quantity of liquid allowed in a laboratory work area is governed by NFPA 45, Standard on Fire Protection for Laboratories Using Chemicals. However, NFPA 30 would cover a liquid storage room in a laboratory occupancy that is appropriately separated from the laboratory work space, as set forth in Subsection 12.6.1 of NFPA 30.
Here are some references and resources directed at a laboratory situation.
- Laboratory Safety Fact Sheet–Flammable and Combustible Liquid Storage and Dispensing: An overview from the University of Pennsylvania.
- Flammable & Combustible Liquids Storage in Campus Laboratories: Fact Sheet from University of California at Berkeley.
- Refrigerators and Freezers: Storing Flammable Liquids — University of Washington
Reference material for this webpage included the following:
- Chemical Safety and Disposal Guide, University of Wisconsin-Madison, 2005
- Red Book: Your Guide to Handling Flammable Liquids Safely. 2008, Justrite Mfg. Co.
- Accident Prevention Manual for Business and Industry–Engineering & Technology, 11th edition. National Safety Council.
This publication was prepared for environmental, health and safety staff at University of Wisconsin System campuses, to assist in finding resources and information for regulatory compliance. It is not intended to render legal advice.
(Read full legal disclaimer.)