Recent positive-pressure ventilation experiments in an abandoned Chicago high-rise have helped to put some hard numbers behind experience and anecdotes.

A team of investigators from the National Institute of Standards and Technology, the Chicago Fire Department, and the Chicago Housing Authority conducted live burns in a 16-story building to better understand smoke management, temperature management and travel of fire throughout a building, according to Chicago Fire Department Commissioner Raymond Orozco.

The live burns, which were conducted on the third, 10th and 15th floors of a former public-housing structure on the city's South Side, were a unique opportunity, said Daniel Madrzykowski, an engineer with NIST's Building and Fire Research Laboratory. “NIST has been looking for a number of years to do a live burn in a high rise,” he said.

While many in the fire service believe that PPV can be a useful firefighting tactic, there are few studies that quantify its usefulness. Although we know PPV works, Orozco said, “firefighters say ‘show me.’ PPV is standard equipment, but there is no science behind it. We need to establish benchmarks.”

Eleven NIST researchers and more than 70 CFD and CHA staff spent two weeks preparing the building. Temperature and pressure monitors were installed on each floor, and cameras, heat flux gauges and typical apartment furnishings were added to the three burn floors.

Once the fires began, researchers conducted a variety of ventilation tests. In one test, the Chicago Fire Department's Mobile Ventilation Unit was placed at the front door while firefighters used an aerial to ventilate the fire room on the third floor. The MVU created a “cone of air over the doorway,” said Madrzykowski, which helped to push heat and smoke out of the building so that firefighters would have cool air at their backs.

In another test, two smaller fans, one on the first floor and another two floors above the fire floor, were used to force air into the stairwell. According to NIST, “Preliminary results from both scenarios show that PPV significantly reduced the temperature and amount of smoke in the corridors and stairwells outside the burn rooms. In one case, the temperature quickly dropped from … 600° to 60°F.”

Fans from Euramco Safety, Super Vacuum Manufacturing and Tempest Technology were used in the PPV tests. Fire departments from New York City; Delaware County, Pa.; Toledo, Ohio; and Ottawa, Canada, also participated in the exercises.

A NIST report on the tests is expected in the spring of 2007.