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PPV testing at Chicago live burns
by Bobby Halton
The National Institute of Standards and Technology (NIST), which functions as the national testing lab for fire related issues, has been engaged in a series of scientific tests to determine if it is safe and effective to use positive pressure ventilation in high-rise buildings. NIST conducts unbiased testing on gear, tools and furniture, even going so far as re-creating incidents to model what happened at specific fires. The researchers at NIST are highly educated scientists with backgrounds in firefighting, a passion for what we do and for keeping us safe.
The use of positive pressure ventilation has long been a controversial tactic in structural firefighting. Due to varying reports on its use, PPV became a Hatfield and McCoy type of topic -- either you never used it or you used it all the time. The Fire Service needed real scientific evidence to help us formulate our thoughts as to whether or not to use positive pressure as a tool in firefighting.
The NIST high-rise PPV study measures what effects the use of fans had on the movement of smoke in a high-rise building. NIST set up multiple thermal sensors and cameras -- both thermal and video -- to document what effect the fans had on the heat and on the fire compartment itself. NIST utilized real furnishing and measured the weight and fuel load for consistency in testing. NIST also set up a wind-driven fire to study what happens when high winds accelerate fire down a hallway. NIST examined if fans can be used to counter this phenomenon and how they need to be set up.
NIST set out to answer many of the same questions we all had: How did the fans work with the open hallways on each floor? How do you create a "pressurized" effect behind the fire if the hallways are open? We understood the use of PPV in being able to positively pressurize the attack stairwells, but getting it to pressurize the public hallway, which is often times untenable, was a major concern. We clearly wanted to know if it could combat wind-driven flame fronts.
To accomplish the testing, NIST used several different types and sizes of fans with varying capabilities. They positioned the fans in various locations to determine the effect and the possible sequencing. Thermal couplings measured the heat movement and fluctuations. The Chicago testing was observed by members of Toledo FD, FDNY Chicago FD, Ottawa Canada FD and Fire Engineering Magazine.
These same departments also lent manpower and experts to consult with NIST regarding the study. The Toledo and Chicago FD provided extensive support to NIST to complete its mission. Regardless of the point of NIST's study, we can be assured the leadership of these outstanding organizations are dedicated to firefighter safety and survival. Additionally, the firefighters of these organizations should be recognized for donating their time and energy in this study. That is brotherhood; that is never forgetting; that is what the job is really about.
The results of the study are not yet available: This was scientific testing, and one more set of tests are still scheduled. Then the long and difficult task of interpreting the data will be need to be completed. The final document should be available by April, and a presentation on the findings will be given at FDIC 2007. Fire Engineering will publish the results as soon as they are available.
