Command and control ics chapter 3. NFA Fire Flow Formula

• The amount of water needed for effective fire control is critical in determining strategy and required resources.
• Preplanning is the best time to determine the estimated amount of water needed, allowing for assessment of construction and specific conditions.
• Preplanned fire-flow information allows for quicker and more accurate decisions upon arrival at the incident.
• Fire-flow formulas are usually complex and better suited for preplanning than rapid field calculations.
• Experienced fire officers can often estimate needed fire flow based on their experience in similar situations.
• The Needed Fire-Flow Formula can be used as a tactical tool to determine fire-flow requirements at the scene.
• The NFA Fire Flow Formula is taught at the National Fire Academy and provides a starting point for deciding water amount, apparatus, and number of companies needed.
• The NFA Fire Flow Formula evolved from the Iowa Fire Flow Formula, also known as the Royer Fire Flow Formula.
• The Iowa Fire Flow Formula (Length × Width × Height ÷ 100 = Gallons per Minute) was developed by Keith Royer during World War II for shipboard firefighting.
• The Iowa Formula is accurate for compartmented spaces that remain sealed, enabling smothering concepts.
• The Iowa Formula was designed for use under specific conditions:
  • The compartment must remain closed until the total fire flow is ready.
  • Charged hoselines would inject a 30-degree fog pattern into the fire area through small openings.
  • Nozzles would be shut down after 30 seconds, followed by entry to extinguish the smoldering fire.
• The Iowa Formula may not meet the needs of structural firefighting due to search and rescue operations and ventilation.
• NFA course developers created a formula for quick calculation using length and width dimensions and a 10-foot ceiling height assumption.
• The NFA quick-calculation formula: gpm = L × W / 3
• The NFA formula was derived from successful fire flows and interviews with experienced fire officers.
• The NFA Formula establishes the relationship between the area involved in fire and the water required to extinguish it.
• Both the Iowa Formula and the NFA Formula are empirical and for compartment fires, but become inaccurate above 1,000 gpm.
• The NFA Formula is designed for aggressive interior fire attack in conjunction with venting activities.
• The NFA Formula for a 10-foot height compartment produces a fire flow 3.3 times greater than the Iowa Formula, compensating for water inefficiency due to venting.
• The NFA Formula calculation typically includes additional water equivalent to a backup line.
• The full fire-flow formula, mainly for prefire planning: gpm = [(L × W) + Exposure Charge] × Percent Involvement / 3
• The Exposure Charge is part of the formula before taking the percent involvement.
• Exposure charges:
  • 25% for each side of the fire compartment with one or more exposures
  • 25% for each floor above, to a maximum of five floors
• Round numbers to make the fire-flow formula easier to apply.
• The calculated gpm can be divided into parts: one part to extinguish the fire and another to protect the exposures, or all can be used to extinguish the fire if exposures do not need protection.
• The first column of fire flow charts must be a percentage that allows a fire flow of no more than the first-alarm fire-flow capability.
• If the percentage of perceived fire is above the first column percentage, additional alarms are needed to handle the fire flow required.
• Fire-flow information on a prefire plan helps in making decisions on resources required.

Compartments

• A compartment is any division into which a space is partitioned off.
• Both the Iowa Formula and the NFA Formula are designed for fires in compartments.
• For an office building with varying-sized offices and no common attic, each partitioned space is a compartment.
• The fire-flow formula is applied to the largest fire area or fire compartment.
• Knowing the fire flow for the largest compartment means that amount of gpm flow will extinguish a fire in any of the smaller compartments.
• The fire flow would be calculated with a basic formula (gpm = 24 ft × 30 ft + (0.25 × 240) / 3), plus consideration of involvement percentage requiring a formula flow
• In a larger commercial building with a partition creating two compartments, use the largest compartment measurement for the fire-flow calculation.
• The smaller compartment is treated as an exposure at 25 percent.
• For a strip shopping center with a common roof (not a common attic space), calculate using the largest compartment, accounting for exposures on each side.
• For a strip shopping center with a common attic space, calculate the entire area under the common attic space as one compartment.
• The Insurance Services Office (ISO) Formula is too complex for incident scene use and is better suited for fire prevention officers and building officials.

Fire-Flow Guidelines

• The Needed Fire Flow formula is designed for aggressive interior operations.
• Fire involvement percentages above 50 percent are not normally interior attack situations.
• The formula becomes increasingly inaccurate above 50-percent involvement or with flows over 1,000 gpm.
• It is not designed for defensive or master stream operations.
• Other variables may affect the needed fire flow, such as fire load, fuel involved, and construction features.
• All three formulas are correct when used within their individual design parameters.

Conclusion

• Following the Command Sequence helps ensure that critical cues, problems, and solutions are not overlooked.
• The Command Sequence makes you think before you act, helps maintain a proactive mode, and get ahead of the time curve.
• The system is based on a logical, step-by-step thought process allowing it to be used successfully on any type of incident.

Activity 2.1 Suggested Answers

• Problems identified:
  • Fifty-percent fire involvement in one occupancy
  • Smoke in the attic space
  • Probable fire spread to the common attic space
  • Smoke in adjoining occupancies

Activity 2.2 Strategies

• Rescue, confinement, extinguishment, and ventilation

Activity 2.3 Samples

• Strategy 1: Call additional resources to the scene
  • Tactic: Strike a second alarm of two engines and one truck.
• Strategy 2: Rescue
  • Tactic: Engine 1 to quickly search adjoining occupancies to the right side of the fire.
  • Tactic: Engine 2 to quickly search adjoining occupancy to the left of the fire.
• Strategy 3: Confinement
  • Tactic: Engine 1 to position a handline in the occupancy to the right of the fire.
  • Tactic: Engine 2 to position a second handline in the occupancy with Engine 1.
  • Tactic: Engines 3 and 4 to position handlines in the occupancy to the left of the fire.
• Strategy 4: Extinguishment
  • Tactic: Engine 1 pump operator to spot E-1 in front of fire occupancy and apply master stream device to the fire.
• Strategy 5: Ventilation
  • Tactic: Truck 1 to vent the roof over the fire occupancy to stop horizontal extension.
  • Tactic: Truck 2 to open the building horizontally front and rear.

Chapter 2 Questions

• Six steps in the classical decision-making methodology: gather information, analyze the information, determine the problems, prioritize the solutions, select the tactics, and issue directives.
• Four steps in the naturalistic decision-making methodology: look for certain critical cues, relate cues to previous similar situations, recall previous conclusions, results, and actions that best fit the new situation, and issue directives.
• 12 percent of incident commanders (ICs) had simultaneous comparisons or relative evaluation of two or more options (Klein and Associates study).
• A cue is a sensory observation which leads a decision maker to relate to previously encountered situations
• The classical method of decision making is appropriate: when in training, when evaluating and planning, when working with case studies, and when cues are not readily seen due to inexperience.
• Naturalistic decision-making method is experience-based and learned through incident experience or training.
• Three action steps and three results in the command sequence: size-up/problem identification, strategy and tactics/action plan, and implementation/tasks.
• Size-up is the process of gathering and analyzing incident information affecting decision making.
• Preincident information available to fire departments: knowledge of buildings, water supply, construction, prefire planning documents, building inspection documents, environmental considerations, and time of day/year.
• Problem identification is the first objective of size-up.
• Elements of WALLACE WAS HOT: Water, Area, Life, Location/extent, Apparatus/personnel, Construction, Exposures, Weather, Auxiliary appliances, Special hazards, Height, Occupancy, Time.
• It is critical for an incident commander (IC) to predict situations to determine problems, even those not visual or verbal.
• Lloyd Layman’s seven factors for the development of strategy: Rescue, Exposures, Confinement, Extinguishment, Overhaul, Ventilation, and Salvage.
• Tactics are the operations completed successfully to accomplish the strategy.
• Action plan elements: objectives (statements of guidance), strategy (what), tactics (how), and communications/medical plan (who, where, and when).