This being said I have been in fires where ventilation has not occurred and witnessed roll over and penciling in the smoke. This proves that there is enough o2 in the smoke to have a rollover leading to flashover.
That's true. Inside our flashover container we perform two kinds of burn. In the first one, we extract the smoke and let a ceilling of flame, in order to the trainees to see the effect of pulse. On the second kind of burn, we ventilated the fire by the bottom, but let the top part of door closed. So we have a heavy ceilling of black smoke.When you pulse inside, you create a hole and see that flames are INSIDE the smoke, invisible. During one burn, we've made some measure and discover O2 level in smoke was no lower than 17%!
In fact, in many case when you start to see flames at the junction between fresh air and smoke, it's too late.
An attack that you do not choose to vent on is a gamble that the fire is not impeding or spreading to impeade egress as well as a risking that you can find the seat of the fire before conditions change ie windows or structural components failing.
The fire depend on fresh air intake. It's like inside a chimney.If you change the air intake, the fire will change. If you don't change it the fire will not change. So windows failling never happened if you let the fire in its original state.
Also, as we advance to the seat of fire, we use pulsing techniques which have a vey good cooling effect, but without producing steam. This disminish the temp of gases and disminish the risk of collapsing and dilute the gas, avoid ignition.
For that, we must use a high GPM selectable gallongae nozzle, but use it at low flow rate. If you have such nozzle, you can test that at the fire station: use a 44mm hose line and a 135 GPM nozzle. Set it to low flow (about 40GPM). Then, turn the head full left, and turn back about one centimenter (1/2 or 1/3 of an inch) to the right, in order to have a 60° cone angle.
Being on your knees, hold the nozzle at 45° from the ground. Then, open it as fast as possible, and as the lever is at the full opened position, immediatly close the nozzle as fast as possible. Don't stop in the "opened" position: this must be a "go and back" movement.
You will see a fine cloud of dropplets, of about 3 feet diameter, flowing just in front of you. That's the way we cool and dilute the gases. Then we adance 3 feets (to be in the zone we cool) pulse again an so on.
Opening and flashover. In many cases, FF are afraid of flashover. But you don't have to be afraid as it strictly impossible to be catch in a flashover. What's happening are vent induced flashover which are trigged by FF themselves."
I believe your talking about a "Roll Over"(or flame over) trainer not a "Flash Over" trainer. I know they call them a flashover trainer.A flashover is when EVERYTHING in the room ignites at once and you wont survive that more than a few seconds even with full PPE. It is generally an explosion. Roll over or flame over, as long as you are low you can survive that. Rollover generally proceeds a flashover. The containers that burn in the front and you watch the flames overhead.. thats not a flash over.
Sorry, I don't understand: you quote one of my paragraph, where I don't talk about "training system" but of event and you "quote" about training system?
In the paragraph "What's happening are vent induced flashover which are trigged by FF themselves" I talk about what's happening during a real fire (eg in a house). The flashover is a full expansion of fire in all the room (this is NOT an explosion. Explision can be backadrft or fire gas ignition type of smoke explosion. See the http://www.tantad.com web site for article about FGI).In order for a flashover to happened, you must have a radiative feed back effect of abou 20kw per meter square. This can only happened if you have enought ventilation.
In fact, during my course I give a simple example: you have a bedroom in fire, with the door wide open. You will have flashover in 3 min. If you close a little the door, you will have it in 4 min, close a bit more the door will produce the flashover in 5, a bit more 6. But each time, as you disminish the air intake, the heat release rate curve is lower. And, at a moment, even if the door is not closed, the air intake will be enought to let the fire "live", but not enought to let it rise to flashover.
In this state, the fire will continue: it will go from the sofa to the harmchair, then to the TV, then to the carpet and so on, but without being able to produce enought heat to start the flashover phenoma.If you open the door, you change the air intake and then the fire can rise again and flash. When the initial air intake is enought, you have a flashover. When the initial air intake is not enought and that the change of air intake change the situation, you have a vent induce flashover.
Concerning the "flashover simulator", I agree. I start builind such system in 2003 and have been about 400 times inside. We can see all warning sign, buy never go to flashover. When I instruct instructor I always indicate that to them; you can see roll over, you can see dancing flame, bubble of gazes, and so on. Sometimes, we can also see a little "black fire", but the amount of fuel is too small and the container too big to go to flashover.
But one point: we are an international organisation, and actually, the Belgium team is testing a third kind of burn. In this burn, they add a wall in the middle of the container, with a window and a door. When the wall is a 20 feet, the "room" is too big to go to flashover, but when they put the wall at 10 feet, they go to flashover inside this room. We are studying that and the last video they send me show flashover in that room, with flames touching the ground.