Closing of the Door Technique


We have heated up a Polyurethane (PU) Foam Chair to the left of the screen out of sight, by placing an ignition source against it, which decomposes the chair and produces high energy combustible gases (smoke), that subsequently ignites, producing a flame that creates sideways radiation onto the chair and some more high energy combustible gases are generated which rise and collect in the ceiling of the room.

The images that follow are from a thermal image camera and the higher temperatures are represented by red on the screen and there is a thermocouple positioned in the ceiling and another thermocouple located at floor level and the variations in temperature readings are shown in Fahrenheit at the top and bottom of the screen respectively.

At the early stages of the fire development the only door leading into this single room (compartment) is open with Fire-fighters (FF) in the doorway with full PPE & SCBA and a charged line with a spray branch (nozzle).

The only variation we made to this room inside a house being used for an acquired structure training session at a Kill The Flashover (KTF) Event in North Carolina – USA (2011) was to place a sheet of plasterboard (gypsum board) over the top half of the window in this room, because it was single glazed, rather than double glazed and by doing this we ensured the single pain glazed window did not fail during the initial ‘Lean Flashover’ and by doing this we could replicate what happens inside a room with double glazing. There are no extinguishing agents of any kind used during this footage or anything else down to this room other than the ‘CLOSING OF THE DOOR’ by FF’s following the ‘Lean Flashover’ and when the thermocouple in the ceiling reaching approx. 1050 degrees Fahrenheit and the flame front was rolling out the top of the door and into the corridor.

Then, the FF’s close the door and within 30 seconds the temperature at floor level reduces to 300 degrees Fahrenheit and the flames inside the room are extinguished by the effect of the room becoming simultaneously, ‘Over Carbureted’ with black smoke being produced by the down radiation from the flame front in the ceiling, which is no longer able to escape through the previously open door and the oxygen was forced out of the room by the ‘Over Pressure’ created by the produced black smoke that forces the ‘AIR’ out of the room making the room ‘Oxygen Deficient’. The chair will still be smoldering away in the lower half of the room, but there is no longer a mobile flame front moving on the ‘AIR TRACK’ in the room, because the previous freely available air supply has been isolated by closing of the door and the window remaining in tact.

This ‘Rich Mixture of Black Smoke’ within the room has ineffective become an extinguishing agent in its own right by absorbing the energy (BTU’s) of the flames and displacing all the oxygen in the room. However, there is a subtle difference with the black smoke extinguishing the fire compared to water mist suppression systems. The ‘Black Smoke’ has the ability to not only absorb the energy, but unlike water spray/mist it can also store the absorbed energy within the black smoke and all it needs to ignite this high energy black smoke (combustible gases) layer with a smoldering PU Foam chair (ignition source) is ‘AIR’, which is explains why opening the door to extinguishing the fire within this room is not advisable, without firstly, stablising the room prior to entry by using water spray droplets/water mist to inert the room.

For members of the public, this footage also demonstrates why it is far better upon discovery of a similar fire scenario. That it is safer and more effective to ensure you evacuate/rescue all persons inside the room and simply ‘SHUT THAT DOOR’. Then, get everyone out of the building and summon the Fire & Rescue Service by 999/911 and if available also ensuring you break a manual fire alarm call point. Rather, than leaving the door open to the room on fire, searching for a fire extinguisher and returning to put the fire out because you have been told this is doable, ‘IF SAFE TO DO SO’.

I would suggest that by closing the door to this room on fire with a double glazed window, it will have become a stable room, full of black smoke and go into a decay phase, with a smoldering chair before a fire extinguisher could even be found let alone deployed.

A full explanation of these techniques and it’s operational application is available in the book – Smoke Burns.

John Taylor                                                                            17 August 2015