Flammables and Combustibles

Flammables and combustible chemicals are easily ignited and may present a serious fire or explosion hazard. 

The lower the flash point of flammable liquids, the more dangerous it is.

• Flammable liquids have a flash point below 100°F. 
• Combustible liquids have higher flash points of 100°F to 200°F.

Flammable solids include finely divided solid materials which, when dispersed in air, could ignite. Flammable solids have an ignition temperature below 212°F

Other classes of chemicals with a high fire hazard include oxidizers, pyrophoric chemicals, and water-reactive chemicals.

• Keep flammables away from all ignition sources: open flames, hot surfaces, direct sunlight, spark sources.
• Store flammables separate from other hazard classes, especially oxidizers and toxics.
• Separate flammable gases from oxidizing gases with an approved noncombustible partition or by a distance of 20 feet. 
• Store flammable liquids in approved safety containers or cabinets.
• In instances where static electricity may accumulate and ignite flammable vapors, ground and bond flammable liquid containers. 
• Know where the lab fire extinguishers are located and ensure all lab staff are trained in their use.
• Keep flammable liquids that require cold storage in flammables-safe or explosion-proof refrigerators or freezers . Retrofitting household-type refrigerators for use with flammables is prohibited! 

Flammable liquids must be stored in a refrigerator/freezer that is specifically designed to house 
these liquids. Flammable and explosion-proof refrigerators/freezers that comply with NFPA 45 and 
OSHA 29 CFR 1910.307 standards are approved for flammable liquid storage. However, flammable 
materials may be stored in a nonflammable-approved (e.g., household-style) refrigerator or freezer 
ONLY under Exception A or Exception B, below:

Exception A
This exception is applicable to reagent kits of small volume such as are commonly found in 
biological and biomedical-type labs. Often, one or more of the reagents in these kits contains an 
organic solvent such as ethanol or acetonitrile in a concentration which is often a trade secret. 
Many of these kits need to be stored cold. This exception also applies to small Sepharose columns 
wetted with a mixture containing ethanol or other flammable solvent.

1.  To comply with this exception, conditions 2 through 4, shall ALL be met.

2.  Flammable solvent(s) present in the reagent shall have a boiling point equal to or higher than 
methanol (boiling point 64.7 °C, 148.5 °F).
      •  Methanol, ethanol, acetonitrile, 1-propanol, and isopropanol are examples of acceptable 
solvents.
      •  In the case of a solvent containing a mixture of chemical species and, therefore, boiling over a 
range of temperatures, the initial boiling point shall be taken.

3. Individual bottles shall NOT contain more than 15 mL of flammable reagent.

4. Reagent kits shall be stored in secondary containment with air-tight lids.
      •  Lids shall be secured by clasps, threaded, or a tight press-fit.
      •  Secondary containment shall be of adequate quality and construction to give reasonable assurance of an air-tight seal.

5. Decent quality food storage containers designed to be air-tight should be generally suitable. Other 
possibilities include polyethylene screw-top containers with good seal (e.g. Nalgene™ brand).

6. Secondary containment with warped lids, cracking, damaged sealing surfaces, or where rubber gaskets or other seals are missing shall NOT be used.

Exception B
This exception applies to cases which do not fall under exception A.

1. To comply with this exception, conditions 2 through 4 shall ALL be met.

2. The flash point shall be:
      •  At least 120 °F (48.9 °C); OR
      •  At least 100°F (38 °C) AND the flammable material is an aqueous solution containing more 
         water
         than solute.

3. The total quantity of flammable material in the fridge or freezer shall not exceed 1 L (liquid) 
or 1 kg (solid).
      •  If flammable solids and liquids are both present, then the sum of the mass of solid in kilograms 
         and the volume of liquid in liters shall not exceed 1 (one).

4. All vessels containing >1 mL of flammable material shall be stored in an appropriate plastic or 
metal secondary container with a sealable lid. The secondary container shall be:
      •  Durable (not readily breakable); AND
      •  Fitted with a secure air-tight lid; AND
      •  Not be susceptible to degradation by materials stored in the refrigerator/ freezer.

NOTES

The definitions of flammables and combustible liquids used here were set using the Global 
Harmonization System. However, Fire Codes may use the definitions and classifications addressed in 
Subsections 3.3.33 and Chapter 4 of NFPA 30.

This standard is based on the 2000 Kentucky Fire Prevention Code that references NFPA 30 and NFPA 45. University laboratories are classified as a Class B (Moderate Fire Hazard) and the following listed quantities comply with that classification.

1. The total amount of solvents within the laboratory shall not exceed ten (10) gallons per 100 sq.ft.
2. The total amount of unprotected solvents within the laboratory shall not exceed (see definitions) five (5) gallons per 100 sq.ft.
3. Solvents in excess of the amounts listed in item #1 shall be in an inside (bulk) storage rooms meeting NFPA 30.
4. Flammable solvents (i.e., flash point < 100°F) must not be stored in an ordinary refrigerator. Must use an explosion proof refrigerator or flammable safe refrigerator.

Definitions

• Solvent: any flammable or combustible liquid with a flash point below 200°F, including hazardous waste.
• Unprotected Solvent: any solvent not in a flammable liquid storage cabinet or safety can.
• Flammable Liquid Storage Cabinet: a metal cabinet meeting the design and construction requirements of NFPA 30 and having been tested and listed by Underwriters Laboratories (UL) or Factor Mutual (FM) Laboratories.
• Safety Can: a metal can meeting the design and construction requirements of NFPA 30 and having been tested and listed by Underwriters Laboratories (UL) or Factor Mutual (FM) Laboratories. The safety can shall be a maximum 2-gallon capacity.
• Inside (Bulk) Storage Room: a room constructed to meet the requirements of NFPA 30.
• Laboratory: Room/space within four defining walls or an open-area concept defined with positioning of lab work benches/shelving.
• Ordinary Container: A glass container no larger than one gallon or a metal can no larger than five gallons.

Recommended Practices

• Glass containers should be limited to 1 pint in size whenever practical
• Transferring of solvents should always be done in a laboratory hood or an approved bulk storage room
• Rubber carboys should be used when carrying 1-gallon glass containers of liquid
• All 5-gallon metal cans should be stored in an approved flammable liquid storage cabinet or in an approved bulk storage room
• Glass containers not in use should be stored in flammable liquid storage cabinets