Different Dragons

Why can't we apply European firefighting tactics in the U.S.? 

When I did ride-alongs with the Copenhagen Fire Brigade this past May (2011), I got my first taste of “Three-Dimensional” or “Compartment” firefighting. I was struck by the stark contrast between American and European fire tactics, high-pressure/low-flow vs. low-pressure/high-flow, for example. The question which arose for me was “why can’t we use European firefighting strategies in America?” because their strategies stuck me as more precise, scientific, and much easier to perform.  

I suspected that the differences in our tactics were rooted in our fires, and that our buildings were changing the fires. So far I was on the right track, but then I got off target. I keyed in on the different materials we construct our buildings out of, Denmark for example has very strict limits of what can be used in a structure and what cannot. In contrast, American builders can use just about any materials they want. However, as I learned, the material difference between our structures accounts for only a small part of the large difference in our fires.

This past December (2011) I traveled to Ireland and learned it’s not what our buildings are made of that make our fires different, it’s how our buildings are put together. The "built environment" changes both how the fire develops and potential options for engaging it.

A typical home in Ireland is divided into many small rooms separated by doors. It has no basement. Balloon frame construction (where exterior wall studs run from the foundation to the top floor creating hidden channels in which the fire can travel vertically through the structure) is not used. American homes are larger, typically have basements, and most significantly, open floor plans with large interconnected rooms.

Typical Irish Home

First floor plan of larger american home with open floor plan. Note the interconnected rooms. 

A fire can be classified as one of two types; these are ventilation-controlled and fuel-controlled. An example of each would be as follows: fuel-controlled, fire starts in a set of curtains, consumes them and goes out before catching anything else on fire. The curtain fire was fuel-controlled because it had plenty of O2 but it ran out of fuel, the curtains, and died. A ventilation-controlled fire develops in a room, and because of how furniture and materials are positioned in the room, the fire has all the fuel it needs and grows until it has exhausted all the O2. In Ireland most fires are ventilation controlled because they start in a small closed compartment (room) with a limited quantity of O2.

If a fire grows with enough fuel and O2 at its disposal, it will likely reach a state of development called "flashover". Flashover can be defined as the point in which all the combustible surfaces in a compartment are burning. It’s very difficult for a fire to reach flashover in a small closed compartment, for example a room in an Irish home, because of the limited amounts of O2. 

Irish Fire Brigades usually fight fires which haven’t flashed over, and remain confined to one room. Appropriately, their strategies, tactics and equipment are oriented towards engaging this type of fire.  In America, fire reach flashover frequently and when they do, quickly migrate throughout the structure.

Fire almost at flashover, note that some materials at the bottom of the compartment are not yet burning but have begun to off-gas (smoke)

So, that covers the differences between our fires, now let's talk about the tactics and strategies used to fight them. In the US, we use a larger diameter hose with a high gallonage stream, which gives us a lot of penetrating power and the ability to apply water from a greater distance. Aggressive fire attack is combined with ventilation, either vertical or horizontal. Vertical ventilation is when you cut holes in the roof of a burning structure, allowing smoke and hot fire gasses to escape. Horizontal ventilation is done by taking windows out. The goal of either type of ventilation is to release heat and fire gasses from the structure, making the inside more hospitable and improving visibility. America’s higher water flow is needed to deal with a more developed fire. Simply put, as the fire’s size and heat increases you will need more water to extinguish it. This strategy has two disadvantages. Water damage: more water flow equals less control, equals more water ending up not on the fire. Accelerated fire growth due to ventilation: while improving the environment inside the structure, ventilation also accelerates the speed of combustion and fire growth.

Vertical ventilation

In Ireland firefighters use a high pressure stream which has limited reach and flow. However, because the stream is at such a high pressure, the water is broken into small droplets which absorb heat quickly. Irish firefighters advance into the structure applying short pulses of water to cool the ceiling area and prevent the fire from extending above and behind them. Once they find the fire room they have a procedure for mitigating backdraft or re-ignition of the compartment by quickly opening the door a small way and applying short shots of water. No ventilation is performed until the fire is completely knocked down, because in an Irish home, the fire is typically ventilation controlled and they want to keep it that way. The smaller rooms limit the distance a stream of water has to reach. Additionally, fire gasses are confined to a smaller space, and water, once converted to steam, remains trapped in the compartment, occupying the space the fire wants to be in.

The Pros and Cons of American and Compartment Firefighting

American Fire Tactics

Pros: 

• Water streams have excellent reach and penetrating power, allowing water to be applied from a greater distance.
• By ventilating a burning structure, attack and search teams can work in environments which would otherwise be unbearable, even with turnouts and SCBA.

Cons: 

• Water damage is significant. 
• Larger hose is difficult to maneuver.
• A compartment or structure which needs ventilation will be pressurized with smoke and fire gasses. By releasing those gasses, you lower the pressure inside, drawing in fresh air. This is a mixed blessing, because while it may provide breathing air to victims, the influx of O2 rich air will accelerate combustion.   

Compartment Fire Tactics

Pros: 

• Small high-pressure lines are easy to handle and advance quickly. 
• Water can be applied with near-surgical precision, minimizing damage. 
• Small water droplets convert to steam quickly, absorbing a tremendous amount of heat. 

Cons:  

• In a larger compartment, steam doesn’t stay confined to the area to interrupt combustion.
• The reach of the low volume stream is limited, especially if it’s being used on a wider pattern, requiring firefighters to get much closer to the fire. 

In conclusion, the reason we do not use compartment firefighting tactics in America is because they're tailored to engaging ventilation controlled fires in small compartments. In America we often encounter fires which are relatively uncontrolled and are burning in multiple interconnected spaces. The low-flow/high-pressure hose is a surgical tool for fighting a specific type of fire, to take it into a lightweight American home with an open floor plan would be like charging into battle with scalpel. 

Although compartment firefighting as a whole may not be applicable to the American fire, there are still many lessons European and American firefighters can learn from each other. These tricks of the trade and solutions to common problems interest me, and I hope to learn more of them as I continue to travel. 

I would like to thank S/O John Chubb of the Dublin Fire Brigade, for taking the time to sit down and go over this with me. It meant a lot, and was absolutely the highlight of my time in Ireland.