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.