Breaking Down NIST's "Fire Dynamics"

The author breaks downs some of the common and repetitive themes that were brought to his attention at the "Fire Dynamics for the Fire Service" seminar.The National Institute for Standards and Technology (NIST) "Fire Dynamics for the Fire Service...

This is also noted in the high-rise pressure ventilation tests in Chicago. Likewise, when one study looked at a basement fire, in the simulated test the TIC (located on the first floor) showed slight indications of heat from the basement; however no indications of floor collapse were seen. Mannequins on the first floor stayed in place for approximately five minutes, supported by carpeting alone. As Madrzykowski stated in this specific example "we need to understand the structure" better, in order to begin the initial attack. This should cause us to review past LODDs and near-miss reports were members fell into basements.

Positive Pressure Ventilation
You will never be hard pressed to find debate about the use of positive pressure ventilation (PPV) fans in the initial attack. NIST's information does not become mired in that battle, but efficiently provides the data from their research on PPV use. There is a ton of detailed information in the presentation and here are some key points:

  • The energy release rate may increase (when using a PPV fan), but the fire does not get hotter (remember, the concern is not so much on temperature but the energy and its transfer).
  • In the "room fire test" (single, furnished room) the fan use did cause a 60 percent increase in the burn rate during the attack, but it was venting outside of the structure.
  • To properly coordinate PPV fan use with the initial attack suggests that companies wait 60 seconds for the fire to react to the introduced oxygen. Doing the 360-degree size-up takes just as much time.
  • In the Toledo highrise test, the fire in the building alone produced greater carbon monoxide (CO) than the PPV fan used. The tradeoff between a slight amount of CO for a smoke filled corridor should be obvious.
  • In the FDNY tests, NIST looked at the amount of CO produced in a dwelling and determined that running power saws inside, produced greater levels of CO (500 parts per million) than the PPV fan.
  • The PPV in schools test (Toledo) proved that a department with minimum staffing can effectively utilize PPV to remove the hazard from the occupants, in cooperation with a well organized initial attack.
  • There has to be a better way to combat high-rise fires than sending crew, after crew, after crew, down a hallway with 2 1/2-inch handlines.

We are being faced with honestly questioning some of our current tactics. What was developed many years ago should be able to be scrutinized to see what can be done better. Certainly with departments facing fiscal and staffing problems this is a good idea.

Finally, regarding human nature and learning, it should be stressed that firefighters and officers must fully learn this information in order to pass it along. Bits and pieces cannot be squeezed into a kitchen table skull session or a front ramp roundtable. The fire service owes it to those in the referenced studies who died, to make sure what is being taught is correct. The full information is readily available from Kerber and Madrzykowski. To shortchange any of it, or make it up as you go, could possibly cause severe outcomes.

Human nature is odd. If I were a betting man, I would say that before any of this information is widely adapted and put into use, we may very well see firefighters burned or killed because someone, with only half the information, put a PPV fan in service on the fire floor of a highrise building during a poorly planned fire attack.

Don't think so? Take a look at the YouTube videos showing us using the PPV fan at fires in private dwellings. A well respected firefighter and officer in my area is credited with the quote "a good firefighter knows how, a better firefighter knows why."

Kerber, Madrzykowski and the staff of NIST are giving the fire service the tools to become better. Contact them at, and at for this information.

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