The flash point of diethyl ether is −45°C (−49°F).
This means that at temperatures as low as −45°C, the vapor released by diethyl ether can ignite in air in the presence of a spark, flame, or heat source. Because this temperature is far below normal room temperature, diethyl ether is considered one of the most flammable common laboratory chemicals.
Why the Flash Point Matters
A low flash point indicates:
- Extremely easy ignition
- High fire and explosion risk
- Vapors can ignite even at freezing temperatures
- Open containers can form flammable vapor clouds around them
Diethyl ether vapors are heavier than air and can travel across surfaces, making ignition possible far from the source.
Autoignition Temperature
While the flash point tells us when vapors can ignite, the autoignition temperature tells us when ether can ignite without a flame.
- Autoignition temperature: 160°C (320°F)
At this temperature, ether vapors can ignite spontaneously in air.
Flammability Limits in Air
Diethyl ether has wide flammability limits:
- Lower Limit: 1.9%
- Upper Limit: 36%
This means that ether forms flammable mixtures over a wide range of vapor concentrations, increasing accident risk.
Storage and Handling Safety
Because of its extreme flammability:
✔ Store in a cool, well‑ventilated area
✔ Keep away from heat or open flames
✔ Use spark‑free equipment
✔ Keep containers sealed when not in use
✔ Ground metal containers to prevent static sparks
Additionally, diethyl ether can form explosive peroxides over time, especially when exposed to air and light. Containers should be dated, regularly checked, and disposed of before expiration.
Summary
- Chemical: Diethyl Ether
- Flash Point: −45°C (−49°F)
- Autoignition Temperature: 160°C (320°F)
- Flammability: Extremely high
- Hazards: Easy ignition, vapor accumulation, peroxide formation