Abstract: Heptane pool fires were conducted in a compartment with a ceiling vent, and the effect of the ceiling vent size on fire development was investigated, in which two pool fires of different diameters and six vents of varying sizes were used. The fuel mass loss rate, gas temperature distributions at different locations and the gas concentration at the base of the fire were measured during the experiments. Results show that the oxygen-lack regime and fuel-exhaust regime are defined due to the cause of the flame extinction. In the oxygen-lack regime, the vent size has a small influence on the fuel consumption rate, fuel mass loss rate and gas temperature, while it has an increasing impact on them in the fuel-exhaust regime. Moreover, the oxygen concentration at extinction time increases with the increase in vent size. Smoke descends quickly to the floor and the compartment is filled almost completely with smoke, rendering so the “two-zone” model invalid for the fires in compartment with a ceiling vent.

Key words: compartment fire, ceiling vent, mass loss rate, temperature profile, gas concentration