Are You Putting Enough Wet Stuff On The Red Stuff?

      4. Seven percent of 535 BTU’s = 37 BTU’s of heat released for each cubic foot of normal air

                  16 ft. times 13 ft. times 8 ft. = 1,664 cu. ft.

                  1,664 cu. ft. times 37 BTU’s = 61,568 BTU’s

      5. To raise the temperature of 1 lb. of water 1^oF requires 1 BTU

                  62ºF to 212ºF = 150 BTU’s

      6. To convert the entire 1 lb. of water (at 212ºF) to 1 lb. of steam requires the addition of 970

          BTUs

                   From 212^oF water to 212ºF steam = 970 BTU’s

      7. To convert 1 lb. of water (at 62ºF) to 1 lb. of steam requires 1,120 BTUs

                   150 BTU’s plus 970 BTU’s = 1,120 BTU’s

      8. One gallon of water will absorb 9,330 BTU’s of heat when the water is completely converted to

          steam

                   8.33 lb. (weight of water) times 1,120 BTU’s = 9,330 BTU’s/gal.

      9. Gallons of water required

                   61,568 BTU’s divided by 9,330 BTU’s/gal. = 6.6 gal.

                   6.6 gal. times 2 (apply in 30 sec.) = 13.2 GPM

                   13.2 GPM times .25 (safety factor) = 3.3 GPM

                   13.2 GPM plus 3.3 GPM = 16.5 GPM

NOTE: This method assumes that all the water is vaporized and the amount of water will only blacken the area involved. This method makes no allowance for exposures although that could be factored into the initial dimensions used in the calculations.

  B. Rate-of-Flow (Cubic Foot) Formula Developed by Iowa State University

      Based on the results of the theoretical method described in item “A”, this method was developed

      as a pre-fire planning tool to establish the minimum amount of water application required to control

      a fully involved fire in the largest single open area in a building. Additional lines for back-up and

      exposure protection should be addressed based on the needs identified by the user. In theory, if the

      minimum amount of water identified by the Rate-of-Flow formula can control the fire on the initial

      attack, the need for additional water will be minimized, but should be planned for. Immediate fire

      control with minimal resources also buys additional time for additional resources to arrive.

         1. Formulas: Volume (in cubic feet) of area involved divided by 100 = GPM flow necessary for

             30 seconds

         2. Volume (in cubic feet) of area involved divided by 200 = gallons of water needed

                      13 ft. times 16 ft. times 8 ft. = 1,664 cu. ft.

                      1,664 cu. ft. divided by 100 = 16.6 GPM for 30 seconds

                      1,664 cu. ft. divided by 200 = 8.3 gallons of water required

  C. Simplified formula developed by National Fire Academy

       1. Determine the area of the structure (length times width)

       2. Divide the area by 1/3 to determine GPM for fire area

       3. Allow 25% for each exposure including another room, floor or structure

       4. Determine percentage of involvement to determine water delivery needs

                      13 ft. times 16 ft. = 208 sq. ft.

                      208 sq. ft. divided by 3 = 69 GPM

                      1 interior exposure (25%) 69 GPM times 25% = 17 GPM

                      No exterior exposures

                      Total Required Fire flow 100 GPM*

                      * Rounded to nearest 100 GPM

Flow shown for single area or floor of involvement, must be increased for multiple areas or floors

Note the closeness of results in the methods after discounting the allowance for the interior exposure in the last method.

 

III.HANDLINES AND MASTER STREAMS (3-3)