Magnesium-based S-type Aerosol Fire Extinguishing Agent Formulation Design And Fire-fighting Mechanism

Halon extinguishing agent with high efficiency and innocuity has been eliminated by international pact because of its heavy damage to the ozonosphere.As the substitute of Halon extinguishing agent,thermal aerosol extinguishing agent has the advantages of high extinguishing efficiency and low production cost,and no damage to the ozonosphere. The intention of this investigation is to grope for an S-type aerosol extinguishing agent,which has the low temperature and steady performance of combustion.Based on the work of predecessors,this thesis analysed the advantage and disadvantage of S-type aerosol extinguishing agent.Firstly, major components of the aerosol extinguishing agent were selected and feasibility analysis was done to the combustible agent, the result showed that using magnesium powder as combustible agent was feasible.Next,based on the oxygen balance theory,the ratio of oxidant and flammable agents was determined across characteristic indexes which were combustion temperature,extinguishing time,combustion residue rate and residual corrosion. Orthogonal design was used to optimize the ratio of adhesive and modifier and then the final formula of Mg-based S-type aerosol extinguishing agent had been determined.Finally,the affect of different factors on combustion performance of the agent was studied with Differential Thermal Analysis(DTA),and the combustion temperature,extinguishing time,combustion residue rate,residual corrosion and combustion products of the final formula were tested,the result shows that this formula has good performance and could be used for further engineering application.In addition,the extinguishing mechanism of aerosol extinguishing agent was studied by high-speed photography,the result shows that,the solid particles of combustion products are the principal part of the extinguishing effect,the speed of flame extinction will get an obvious increase when solid particles reach a certain concentration; the main factor affecting the extinguishing efficiency is the time when the solid particles subside and spread to the effective extinguishing concentration.