Test Your Knowledge on Rate of Flow Calculations and Fire Attack Tactics

Study Notes

Offensive fire attack is preferred when conditions and resources permit an interior attack.
Offensive versus defensive decision is based on staffing, water supply, ventilation, and risk-versus-benefit analysis.
Rate of flow calculation is used to match the number and size of fire lines to flow requirements.
There are three rate of flow calculation methods: Royer/Nelson, National Fire Academy, and sprinkler calculations.
Royer/Nelson formula is based on the premise that the best rate of application is one that results in control of the fire within 30 seconds of effective application.
The major assumption of Royer and Nelson is that structure fires are primarily ventilation controlled.
Large-area fires are most likely to require larger hose lines and the application of rate of flow principles.
Ventilation-controlled fires require less water than a free-burning fire.
Underestimation may occur when fires reach a point beyond the capability of an interior attack.
Trial-and-error methods can be useful but should not replace a more scientific approach.
Rate of flow calculations are used to determine the size and number of hose lines needed for an interior attack.
The Royer/Nelson formula (V/100) is valid for most fires where an interior attack is advisable.
The progression to flashover is primarily based on the ratio of the surface area of the fuel to the size of the enclosure.
The National Fire Academy developed the A/3 formula for use in their fire tactics courses.
Large-volume fires require the application of a rate of flow formula.
Sprinkler system calculations may prove useful in preincident planning.
Rate of flow calculations are based on the area or volume of the compartment(s) on fire.
Each individual compartment should be calculated separately.
The IC decides when it is time to use larger, more powerful streams.
Proper ventilation can make the fire more visible and allow effective application of water onto the burning fuel.
Dividing large areas into smaller compartments makes it easier to fight fires.
Fighting fires in undivided areas often requires a defensive attack.
Some advocate calculating the entire area for flow rate formula.
The more rational approach is to calculate each individual space as a separate fire area.
This allows for extinguishing fires one room at a time.
Only the flow needed for the largest area is required if individual spaces are calculated separately.
The text refers to a plan view of an apartment building in Figure 8-3.
Few large areas are undivided.
It is easier to fight fires in a series of smaller compartments.
Fires involving large, undivided areas often require a defensive attack.