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by Ginger Brown
Safety Coordinator
Env. Health & Safety Dept., Texas A&M University

Ethyl ether (a.k.a. diethyl ether, or ether) presents an extreme fire hazard. Ether is highly volatile and has a flash point of -45C (-49F) and a lower explosive limit of 1.9% by volume in air. An open beaker of ether on a lab bench next to a lighted Bunsen burner will ignite. It has a vapor density of 2.5 (air = 1.0); therefore, ether vapors can "fall" from a lab bench to the floor and travel to a spark source which can result in a flashback to the source. Also, vapors can easily accumulate in sufficient concentration in a closed space (e.g. refrigerator) to explode with the slightest spark (e.g. refrigerator condenser comes on). Refrigerated storage does not suppress the formation of ether vapors.

Upon exposure to air and light, ether tends to form unstable peroxides which will concentrate by evaporation or distillation of the ether and may detonate with a violent explosion when disturbed by shock or friction. The friction produced by simply unscrewing the cap of a container of peroxidized ether may cause an explosion. One incident described in the literature reports that an "empty" 250-cc bottle which had held ethyl ether exploded when the ground glass stopper was removed. Ether from a chemical supplier usually contains an oxidation inhibitor and has a shelf life of two years unopened or one year after the container has been opened. Freshly distilled or uninhibited ether may form peroxides in less than two weeks and must be handled with extreme care. There is no evidence that refrigerated storage will prevent formation of peroxides.

Ether can be tested for the presence of peroxides as follows:

** Add 1 cc of freshly prepared 10% potassium iodide solution to 10 cc of ethyl ether in a 25 ml clear glass- stoppered flask that has been wrapped to protect it from light. Shake for one minute, then let it stand for one minute. Unwrap the flask and view against a white background. Yellow color indicates the presence of peroxides.

To prevent fire and explosion hazards associated with ethyl ether, follow these precautions:

  1. Purchase ether in a quantity that can be used within twelve months.

  2. Date the ether to indicate the date received and the date the container was opened.

  3. Dispose of ether that is older than one year.

  4. Keep ether in a metal can or amber bottle to prevent its exposure to light.

  5. Store ether in a well ventilated location.

  6. Do not store ether in a household style refrigerator or freezer. To chill ether, use either a lab-safe or an explosion-proof refrigerator/freezer or use an ice bath.

  7. Always use ether in a properly functioning chemical fume hood.

  8. Make sure there are no open flames present when ether is in use.

  9. Consider substituting a safer chemical such as petroleum ether which has a safer flash point and does not form explosive peroxides.