Evaluation of the suppression effect on the flame intensification of ethanol fire by N2 twin-fluid water mist containing KQ compound additive

Abstract

Water mist is one of the important substitutes of halon fire extinguishing agents with the advantages of clean and environmental protection. However, there will be a short time of flame intensification in the fire extinguishing progress of water mist, which threatening the safety of surrounding combustibles and fire fighters. The main objective of this study is to assess the suppression performance of N2 twin-fluid water mist containing KQ compound additive (composed of 6% fluorine surfactant and K2CO3) on ethanol pool fire, and analyze the suppressing mechanism on the flame intensification phenomenon. Experimental results showed that: the fire extinguishing time of several fire extinguishing agents from low to high was N2 twin-fluid water mist containing KQ compound additive < N2 twin-fluid water mist containing potassium additives < N2 twin-fluid water mist < N2 twin-fluid water mist containing 6% fluorine surfactant < air twin-fluid water mist. Comparing to air twin-fluid water mist, there was no obvious intensification phenomenon of flame in the initial extinguishing stage with N2 twin-fluid water mist containing KQ compound additive, and the suppression effect on the fire was improved significantly. N2 played a pre-inerting role, which could increase the specific heat of the mixture and dilute the concentration of oxygen, resulting in reducing the flame intensity and flame buoyancy. Meanwhile, comparing to potassium salt solution, the compound additive of KQ solution reduced the droplet diameter of water mist, which fastening the generation rate of K ions; and leading to smaller turbulence disturbance on flame caused by water mist. Therefore, the physical and chemical fire extinguishing effects were both improved. Moreover, compound additive KQ reduced the potassium salt concentration by 50 %, hence reduced the corrosion of chemical additives. This research will improve the fire extinguishing efficiency and reliability of water mist fire extinguishing technology.