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" presentation provokes a new era of thought in fireground tactics. The information provided is based upon repeated tests related to events, some tragic, in the fire service.

 

The data that NIST provides is repeatedly tested, absent of outside influence, such as manufacturers or labor organizations, and is openly welcoming of fire department scrutiny. Perhaps what is most encouraging is the purpose NIST seeks to make the fireground safer through knowledge of fire behavior.

Every attendee came away with 10 discs specific to each test in the presentation. NIST presenters Steve Kerber and Dan Madrzykowski specifically stated that the information presented is to be shared, distributed and taught; to think of it as a train-the-trainer concept.

Below are some key, repeated and thought provoking points from their presentation. As you read this don't fall into the common mindset that this is another effort by the safety police to take us out of the interior attack. Nor is it an approach of "slide rule" firefighting, book smart and little experience. Their objectives are clear: develop a better understanding of fire dynamics and how it impacts your personal safety and, make you think more and ask why.

Ask Why
Very few know the specific origins of today's fireground tactics. What was developed approximately 50 years ago and currently in use may not be working in some situations, or may be improperly utilized. There is a huge difference between tactics and theory. What is learned here (presentation) needs to be put to the test in the field.

Firefighters know very little about fire behavior. According to Kerber and Madrzykowski, Firefighter I (102 hours) has three hours of fire behavior. Firefighter II (60 hours) has none. Fire Officer I and II (108 hours) also have no hours specifically devoted to fire behavior. One percent of your initial training is about fire behavior. How much do you remember? What is needed to fill the gap?

Building Construction and Fire Behavior
The average private dwelling has changed considerably in composition and fuel load. While the fire environment changes, the fire service changes slower, if it changes at all. When looking at possible causes, the fire service tends to look for specific single faults in construction and instead, should be looking at the whole of the structure.

The traditional fire curve, or development stages, we learn from our early fire department training has changed. We are now faced with "under ventilated" fires and members being burned or killed in post-flashover fires. Statements of "we only had a small bit of smoke showing" from fireground investigations indicate that we are arriving and making entry at a time when the fire has begun to die or the atmosphere is too rich for flashover. What appears to be a minor or "routine" fire turns severe when entry is made and the room then flashes over. This should lead us to reevaluate our process of size-up and initial report as well as taking the time (seconds) to make sure our initial attack is setup according to what is being seen. Perhaps this is a new use of the old saying "stay low and let it blow."

Heat, Temperature, Smoke and Thermal Imagers
The key about temperature is not necessarily how hot it is but to understand where the energy comes from and the transfer (heat flux) of this energy. As materials begin to burn they add to the fuel load above us (ceiling area). Regardless of whether they are burning or not, they are fuel; smoke is fuel.

In research recreating specific fireground conditions, thermal imaging cameras (TIC) recorded the high temperatures without showing the contrast of actual encroaching flame spread, or rollover. Just like the smoke showing quote, this coincides with statements about how hot it was inside but the fire was not to be seen.

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 madrzy@nist.gov, skerber@nist.gov and at www.fire.gov for this information.

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WILLIAM CAREY, a Firehouse.com Contributing Editor, is a former volunteer lieutenant with the Hyattsville Volunteer Fire Department in Prince George's County, MD. With 20 years, his training is extensive and his experience ranges from a very rural fire department to one the busiest departments among the metropolitan Washington, D.C. area. You can read more of his fire service writings at Firefighter Behavior. To read William's complete biography and view his archived articles, click here. You can reach William by e-mail at william.carey@cygnusb2b.com.

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