The present research is using a Fire Dynamics Simulator FDS tool for computational design the fire spread and
distribution of fire exhaust particles. Therefore, knowing the program capabilities are very important for modeling
this problem. Nowadays, many different applications are using FDS, such as modeling for flow of smoke in different
ventilation conditions, fires in tunnel and multi-floors buildings. The effectiveness of using various water mist flow
rate amounts, different water mist particle sizes and two different fire source positions (corner and center) on the fire
extinguishing time, are investigated through various scenarios of fire suppression by design and build a 1/5-scale of
water mist system throughout FDS model “using PyroSim program", which shows a pronounced effected result. The
firefighting time is reduced with decreasing the water mist droplet size (up to 30 μm). The fire suppression time
decreases as a result of increasing the flow rate of water mist spraying (up to 40 l/min).