Abstract: Closed-cup flash point is one of the important index to assess the flammable hazard of liquids, and the sustained combustibility test is used to determine if a substance sustains combustion when heated under the test conditions and exposed to a flame. By experiments the features of flammable dangerous liquids with closed-cup flash point below 35 ℃ and 55 ℃≤closed-cup flash point < 63 ℃ under different test standards and their sustained combustibility were explored. The results showed that: when the closed-cup flash point of liquid is below 35 ℃， the substance is essessed as not sustaining combustion,and it is proposed for the first time that the liquids can be classified as non-flammable liquids; The liquid is recommended to be classified as flammable liquid if the closed-cup flash point is 55 ℃≤closed-cup flash point < 63 ℃ and the closed-cup flash point is lower than 60 ℃ with a suitable testing method as well as the substance is essessed as sustaining combustion. This study will provide an important reference for further study on the test methods of risk assessment and classification for flammable liquids。

Key words: fire fighting, closed-cup flash point, combustibility test, non-flammable liquids, flammable liquids