Fire flows are used to rapidly gauge the expected amount of water needed for a given percentage of involvement of a structure fire.
Blazemark supports 3 different types of fire flows. NFA and Iowa are automatically calculated given required structural dimensions are entered. The ISO calculation is available if you enter more specific information as required. See below for more details.
QAP NOTE:
ISO Fire Flow can be selected to be in the QAP or not
NFA & Iowa are always included in the QAP
If you have more than one type of Fire Flows active, they will be shown together:
Control Availability/Visibility of Fire Flows
Org Admins can control which fire flows are in use for all preplans under Admin | Manage Organization:
In short, NFA requires at least Length and Width, and Iowa requires Height as well.
Here is a good reference: "Determining Required Fireflow" (Rob Neale, Jan 2018). In case the publication is not available, a PDF is attached below.
National Fire Academy Method
The National Fire Academy (NFA) formula, taught in the Managing Company Tactical Operations (MCTO) classes, is similar to the ISU method, but employs different values and is based on area, not volume. The NFA fire flow formula is:
Required fire flow (gpm) = (Length x Width) ÷ 3
Using the same example, an IC arrives at a burning mercantile occupancy that measures 50 feet by 75 feet and is one story (12 feet) tall. The IC quickly determines that the area of the structure is 3,750 square feet. Using this number and the NFA formula, the required fire flow for this structure would be 1,250 gallons per minute (3,750 ÷ 3 = 1,250).
Iowa State University Method
The Iowa State University (ISU) method was created in the 1950s after a series of studies of fire in enclosed spaces. The ISU “Ideal Rate of Flow” formula:
Required fire flow (gpm) = V ÷ 100
Where V = the volume of the space is on fire.
(Or Length x Width x Height)
Using the ISU formula, an IC can assess the conditions at a burning noncombustible mercantile occupancy that measures 50 feet by 75 feet and is one story (12 feet) tall. The IC can quickly determine that the volume of the structure is 45,000 cubic feet. Using this number and the ISU formula, the required fire flow for this structure would be 450 gallons per minute (45,000 ÷ 100 = 450).
Insurance Service Office (ISO) Method
See a companion article on the more comprehensive ISO Fire Flow method here.
Additional References
Refer to this article mentioned above for additional information on these more complicated computations.
More complicated formulas exist that take into account properties such as construction type, occupancy, rural water supplies:
NFPA Standard 1142, Standard On Water Supplies For Suburban And Rural Fire Fighting Method
International Fire Code (IFC) Method
Illinois Institute of Technology Method
Mobile Water Supplies