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.
- In order to comply with this exception, conditions 2 through 4, shall ALL be met.
- 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.
- Individual bottles shall NOT contain more than 15 mL of flammable reagent.
- 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.
- Secondary containment shall be of adequate quality and construction to give reasonable assurance of an air-tight seal.
Exception B
This exception applies to cases which do not fall under exception A.
- In order to comply with this exception, conditions 2 through 4 shall ALL be met.
- 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.
- 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).
- 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 by the GHS. However, Fire Codes may use the definitions and classifications addressed in Subsections 3.3.33 and Chapter 4 of NFPA 30.
| Chemical | Flashpoint |
|---|---|
| Acetone | 1°F (-17°C) |
| Ethanol | 55°F (13°C) |
| 20% Ethanol | 97°F (36°C) |
| Isopropanol | 53°F (12°C) |
| Methanol | 54°F (12°C) |
| Ethyl Ether | -49°F (-45°C) |
| Isopentane | -60°F (-51°C) |