Refrigeration of Flammables

Containers of flammable liquids are often stored in refrigerators or cold rooms. This is an unsafe practice. Evaporation occurs and in the closed chamber an explosive mixture may rapidly be achieved. A spark from a door switch, light mullion heater, defrost timer, compressor relay, thermostat, or other source can result in an explosion. Cold rooms also may have many ignition sources, typically from fan motors, light switches, or electrical equipment being operated in the room.

Evaporation of flammable liquids can occur even from tightly capped containers. At lower temperatures, this happens at a slower rate but if the chamber is opened infrequently, then the concentration of vapor may still approach the lower explosive limit. Spills of flammable liquids within a refrigerator are also a major hazard. The spark from the door switch when the refrigerator opens will result in an explosion. 

If flammable materials must be refrigerated they should be stored in either explosion-proof or laboratory-safe refrigerators. These units differ greatly but are both suitable for most research laboratory applications. The sources of ignition are eliminated from the chamber, e.g. light, door switch, thermostat, etc. These units possess a magnetic door catch instead of a mechanical latch to eliminate a source of sparks.

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