METHODS OF FIRE ATTACK
–ANDREW A. FREDERICKS
Direct method: Involves direct water application on the burning fuel to cool it below its ignition temperature and eliminate production of vapors that burn.
Indirect method: Developed during World War II as a means of combating fuel oil fires in the confined machinery spaces of large ships and later applied to structure firefighting. Lloyd Layman, the primary proponent of what he called the “indirect” method of structure fire attack, explained the theory and methodology in his book Attacking and Extinguishing Interior Fires.* In it, he identified the key requirements for a successful indirect attack, paraphrased as follows:
Fog streams should be remotely injected into the fire area at the highest possible level from positions outside the involved building due to the danger of steam burns to nozzle crews.
The fire should be sufficiently well-developed, as fires in the first phase or early second phase are effectively suppressed using direct methods.**
Doors and windows in the fire building should be intact (shut), and ventilation must be delayed until after the injection of water fog has ceased.
Indirect attack methods, while potentially effective, have a limited range of application on the fireground and must be carefully employed to achieve satisfactory results.
Combination method: Developed as a result of misunderstanding and confusion concerning Layman`s writings, as well as advances in personal protective equipment and self-contained breathing apparatus that permitted suppression crews to penetrate deeper into fire buildings. The combination attack requires the nozzle team to perform an interior fire attack using at least a 30-degree fog pattern directed at an upward angle and rotated rapidly in a clockwise motion to absorb a maximum amount of heat from the fire environment. As the seat of the fire is reached, clockwise sweeps with the nozzle should also provide some direct cooling of the fuel. The pattern also can be adjusted at this point to a straight stream to provide sufficient penetration for final extinguishment. The combination method is characterized by excessive steam production; zero visibility due to disruption of the thermal balance; and the danger of pushing flammable fire gases, smoke, and flame into uninvolved areas of the building due to the high-pressure zone that exists ahead of all fog patterns. Without appropriate ventilation, the danger of forcing heat and flames up and over the heads of the nozzle team is another real danger.
*Layman, Lloyd. Attacking and Extinguishing Interior Fires. (Boston: National Fire Protection Association, 1952.)
**Chief Layman was one of the first fire service authors to identify the three stages or phases of growth of interior fires: incipient, flame producing, and smoldering.
