Study On A Drug Block For Driving Dry Powder Fire Extinguisher

Dry powder extinguishing agent as halon fire extinguishing agent substitutes with high fire extinguishing efficiency,innocuity,low production cost,simple and reliable operation and other advantages is widely used.Non-storaged type of dry powder fire extinguisher use the high-pressure gas produced by combustion of the gas generating agent to spray the powder into the fire,so as to put out the fire.In order to ensure extinguish a fire,the sprayed dry powder should have faste flow rate and large flow.However,burning too fast,may explode;too slow,dry powder spray weakness.So the gas generating agent needs to have advantages like large amount of generated gas per unit mass,suitable combustion rate,low combustion temperature,less residue,non-toxic gas,non-toxic raw materials,high ignition sensitivity,high and low temperature tolerance,easy press forming,high mechanical strength,good moisture resistance,etc.In this thesis,relationship between oxygen difference,particle size of KNO3,additive,manufacturing process and the burning velocity of the gas generating agent is studied.The powder injection speed and the distribution area of powder was calculated depend on fire fighting test.Tests show that the fire extinguishing device witch has 120g dry powder and 12g gas generating agent,1 meter away from 300 × 300mm gasoline brazier,put out the fire in 2 seconds,without resurgence.In this study,we used digital camera and high-speed camera to record the combustion process of the gas generating agent.Experimental results show that in the range of-45?15 for oxygen difference,the burning velocity increased first and then decreased,oxygen difference-20 has the maximum burning velocity.The burning velocity increase with the decrease of the particle size of KNO3,because the burning velocity is affected by the thermal decomposition rate of KNO3.The electrons of transition metal or transition metal compound on the D orbit can promote the electron transfer during the thermal decomposition of KNO3,thus adding them could promote the combustion.In order to analyze the combustion performance,volume of the generated gas,moisture resistance,high temperature resistance and low temperature were tested.The gas generating agent generates 0.115 L gas per gram(standard state).After 10 days and nights in the environment of 100%humidity,the moisture absorption increment was only 0.84%,and the ignition performance and burning velocity are not affected.The ignition and combustion performance of the gas generating agent remained stablely at-27?-140? storage condition.The result of XRD shows that the mainly solid combustion products of the gas generating agent are K2CO3,KNO3,K2O and C.