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. In order 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.
    • Secondary containment shall be of adequate quality and construction to give reasonable assurance of an air-tight seal.
      • 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).
      • Lids shall be secured by clasps, threaded, or a tight press-fit.
    • 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. In order 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.

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

Acetone1°F (-17°C)
Ethanol55°F (13°C)
20% Ethanol97°F (36°C)
Isopropanol53°F (12°C)
Methanol54°F (12°C)
Ethyl Ether-49°F (-45°C)
Isopentane-60°F (-51°C)