A liquid is considered flammable if it has a flash point below ______ degrees and has a vapor pressure not exceeding 50 psia.

A liquid is considered flammable if it has a flash point below ______ degrees and has a vapor pressure not exceeding 50 psia.

• A. 50
• B. 75
• C. 100
• D. 150

Answer: (C)

Flammability classification rests on the temperature at which a liquid’s vapors can ignite, its flash point. The standard cut-off is that a liquid is considered flammable if its flash point is below 100 °F. The additional requirement that its vapor pressure not exceed 50 psia helps ensure the liquid isn’t so volatile that vapors are persistently present. So the correct value is 100 degrees Fahrenheit. If the flash point were at or above 100 °F, the liquid would be labeled combustible rather than flammable. The other numbers would either exclude many flammable liquids (if the threshold were set too low) or misclassify liquids (if set too high).

Flammability classification rests on the temperature at which a liquid’s vapors can ignite, its flash point. The standard cut-off is that a liquid is considered flammable if its flash point is below 100 °F. The additional requirement that its vapor pressure not exceed 50 psia helps ensure the liquid isn’t so volatile that vapors are persistently present. So the correct value is 100 degrees Fahrenheit. If the flash point were at or above 100 °F, the liquid would be labeled combustible rather than flammable. The other numbers would either exclude many flammable liquids (if the threshold were set too low) or misclassify liquids (if set too high).