Effect of fuel boiling point of pool flame for the flame extinction by CO₂ hydrate

Experimental investigations to extinguish pool flames by CO₂ hydrate powder and dry ice powder have been done. Methanol and 1-hexanol are used as a fuel of pool flames. The boiling point of the methanol, 67.4 °C, is lower than that of the water, while that of the 1-hexanol, 157 °C, is higher than that of the water. A variation in the flame shape to extinction is recorded by a high-speed video camera. Critical mass for extinction, which is defined as a minimum mass of fire extinguishing agent for extinction, extinction time, temperature variation in and above the fuel are measured. In the case of a methanol pool flame, more critical mass of CO₂ hydrate is necessary compared to the dry ice to supply same mass of CO₂ gas. This indicates that the supply of CO₂ gas plays a key role to extinguish the methanol pool flame, which dilutes the methanol gas and weakens the mixing between methanol gas and air. In the case of 1-hexanol, less critical mass of CO₂ hydrate is necessary compared to the dry ice. In this case, the water in CO₂ hydrate dilutes and cools down the 1-hexanol which results in a decrease in the vaporization of the 1-hexanol.