Can average (household type) refrigerators and freezers be used for flammable chemical storage?

No! Flammable-Storage-Rated refrigerators / freezers must be used for storing flammable materials. This rating will be shown plainly on the front of the refrigerator. Refrigerator temperatures are typically higher than the flash points of most flammable liquids. Powerful explosions can occur when an inappropriately-rated refrigerator's open circuitry, typically located at the bottom of the unit, comes into contact with heavier-than-air fumes of flammable liquids. Likewise, similar issues are present with generic freezers. If there are non-flammable-rated refrigerators / freezers located in the laboratory, a highly visible, permanent label must be affixed that states: "Caution: Do Not Store Flammable Materials in this Refrigerator".