Experimental investigation of the effect of obstructions on fire suppression performance of high pressure water mist system

Full scale tests were conducted to study the effect of obstructions on the water mist fire suppression performance in an open space.The obstructions consist of open ceiling grid,cable tray and ventilation pipe.Results showed that the small obstructions such as open ceiling grid and cable tray have little effect on the performance of high pressure water mist fire suppression due to the fine penetration ability of droplets.However,large obstructions such as the ventilation pipe will affect the fire suppression effectiveness.Many droplets obstructed by the pipe accumulated because of the collision.These droplets have no effect on the fire extinguishing ability of water mist due to the resistance of fire plume.But there were still some droplets entrained by the fire will suppression the flame.Therefore when design the water mist system,care must be taken considering of the spray characteristics,type of obstructions and the relevant position between the nozzles,obstructions and the protected objectives.