American Fork (UT) Fire & Rescue Chief Kriss Garcia recently conducted a Webcast entitled “Challenges to Implementing PPA.” Here are his responses to some questions asked during the presentation.
Q. So the more or bigger opening is better?
A. More is better if they are in the fire area through non-survivable exhausts. If you don’t have 2-3 that is where we start. You will know if you have ample exhaust to use positive pressure attack (PPA) by the area above the fan. If heavy smoke that does not clear comes back towards the fan you should adjust by making more exhausts. The faster you can remove smoke and temperature from the building the better. You can figure out how to get the nuisance smoke out after the fire has been knocked down. This is more challenging with substantial exhausts but at that point who cares if it takes an extra 10 minutes to manipulate openings and fans to clear it out completely, the fire is out.
Q. So this is for free-burning fires only?
A. I only use it on free-burning fires, yes; especially as you are just starting to understand PPA.
Q. How do you create the exhaust opening for “the free-burning” attic fire?
Attics are a little different. As an attic is an unoccupied second story with primarily ordinary combustibles, the amount of exhaust needed for them is less than from our synthetic fire loads. I have found that the vast majority of the time the ambient exhausts in the attic are enough to contain the fire above while we work below. If the fire has progressed and has burned away roof or gable vents, these will enlarge themselves as we operate form below in a clear environment. PPA in attic fires localizes the fire to the attic keeping the area below clear so firefighters can work without high levels of obscuration.
Q. How far along are the UL tests on PPV?
A. Burns are supposed to happen this fall/winter.
Q. On an isolated attic fire what are we looking for as an exhaust? So do you only use PPA if the fire is venting through gable or other opening?
A. See the question on attic fires above.
Q. Are not both the victim and the firefighter first? Why can’t you protect both at the same time?
A. We do. We open non-survivable areas, making the remaineder of the structure much more tenable within seconds. I will not put firefighters into hot fuel hoping that the fire will not get air while we are inside. We will clean the burn up, decreasing incomplete combustion in areas that are already not survivable while at the same time allowing firefighters to enter a clearing atmosphere with little obscuration so that they can see any hazard or victims.
Q. We are taught that wind-driven fires are some of the most dangerous that we face. Two questions: First, how does PPA compare/contrast to wind-driven fires and, second, how well does PPA work during fire with heavy winds in the opposite direction of exhaust?
A. Referring to an article of mine on wind-driven fires in Fire Engineering, you cannot beat Mother Nature. You have to enter on the windward side or flank of the structure. We never open a windward exhaust unless it is already breached. If winds are moderate and you are not sure, take exhausts in non-survivable free burning areas and monitor the area above the fan to see if you get any blow back, which means you cannot exhaust enough to use PPA.
Q. PPA for my department is impractical. We run two-man engine companies. four engines, one Tower, two ALS rescues, and one battalion. So with a total max working manpower of 14 firefighters at any given fireground.
A. In my experience with limited staffing, it is not only possible but also more necessary. We pull this off routinely with five firefighters the vast majority of the time.
KRISS GARCIA is chief of American Fork (UT) Fire/Rescue. He retired as a battalion chief from the Salt Lake City (UT) Fire Department, where he worked for 27 years. He is an instructor for the National Fire Academy. He has an associate degree in prehospital/paramedic care as well as bachelor degrees in public administration and education. He is the author of a book on positive pressure attack.