Convective heat energy is our worst enemy when it comes to protecting our skin from heat energy transfer. Think of convective heat transfer (transfer of heat via air currents) much like wind chill. yes.. Wind chill…. or even a better example… cold water in a whitewater river. You see.. in a lake where the water has a very slow velocity the heat transfer of hot melcules transfering to cold molecules is slow therefore it cools our body at the rate of 25 times the rate of air. Whereas, in river where the water current or velocity is much faster, the heat energy from hot molecules transferring to cold is much faster (rate of cooling is 250 times the rate of air) thus robbing of the heat molecules needed to maintain warmth.
Or when the wind is blowing and cools our body at a faster rate. Now…in a fire situation, the cold molecules of our body are robbed at a faster rate when we encounter convective heat energy as opposed to radiant heat. The higher the velocity of heat energy molecules moving past our body the faster our cold molecules within our gear are removed and our gear is heated.Why is this important?
When we view flow paths, pay attention to the neutral zone (NZ) you know…that layer where heated fire gases (including smoke) is traveling towards an outlet and air is traveling towards the fire as seen during a bi-directional flow.When the NZ banks down where the overpressure gases traveling towards the outlet is impinging on our gear this is the convective heat transfer shown in this video that can heat our gear so fast you will not have time to escape a rapidly building modern fueled environment.Your homework..pay attention to the Neutral Zone!! Is it rising or dropping… If it is dropping towards the floor conditions are worsening….Cool this environment immediately and avoid the convective heat energy injury! If it is rising..another outlet may have become available such as an opened door, window or even loss of the ceiling or concealed space