The UL (FRSI) study on PPA (2016)suggest back flow through inlet will always occur. It's noted that continuous monitoring of inlet is important to determine whether back flow is increasing or decreasing to determine adequate exhaust. In all the studies the cone of air completely covers inlet. UL does not mention anywhere any benefits of having cone of air 6" lower for the inlet (video 2013). I'm having difficulty finding research to indicate that cone of air 6" lower is a better option, please advise. Thanks
Would it be possible to use a large heat-resistant fan for negative pressure ventilation near the seat of the fire? I would think that in cases where that would be practical, it would be safer than positive pressure, without the risk of pushing the fire to places where it otherwise wouldn't go.
Chief, thanks for the video. I've never been a big fan of pp attack just because there are too many unknowns. The layout of the house, although somewhat predictable, can never be 100% known. You can never be certain where all the fire is and if you make a mistake the results can be catastrophic. Also as soon as you open the door you will grow the fire and elevate the heat and that's before you throw a fan. With all do respect, it's just to risky. Why not make the conditions more attainable by making a quick exterior knock down, controlling the flow path, then putting the fire out. Use ppv in a much more known atmosphere, after you've made some progress. Just food for thought. I would hate seeing someone get burned because they made the wrong call at the wrong time, because that would be easy to do with pp attack due to all the variables. All the best!
