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Fog Tactics
Bill Nelson’s fundamental principle of fire fighting states that the right amount of water must be applied to a confined fire. To do this a fog nozzle must be capable of doing three things.
First, the nozzle must be able to vary the flow rate from 30 gpm (113,5 Lpm) to 150 Gpm (576,7 Lpm)
Second the nozzle must be able to vary the fog pattern from a straight stream to a wide angle short reach stream
The fog nozzle must be able to shut down immediately.
There are two types of fog nozzles that satisfy these three requirements. One type is an automatic nozzle with a slide type shut off valve with six click (détente) stops on the shut off handle. These stops vary the flow rate from 30 Gpm (113,5 Lpm) to 150 Gpm (576,7 Lpm). The second type is a non-automatic nozzle with a manual volume control ring that varies the flow rate. A ball type shut off valve may be used with this nozzle. Otherwise, the ball type shut off valve cannot be used with a fog nozzle that cannot vary the flow rate. Such a nozzle is restricted to two flow rates—0 flow when shut, or maximum flow when fully open Attempts to flow with the handle partially open results in serious deterioration of the fog stream plus there is no way to determine how much water you are flowing. All of these nozzles are constant flow nozzles, that means that the flow rate does not change with a change in stream width or reach.
There is an art to fighting fires. There is much more involved than just opening a nozzle and pointing it in the general direction of the fire. The following four tasks must be performed in order to make an effective fog attack upon a confined oxygen limited structure fire.
Adjust the width of the fog stream (shorten the reach) so that the stream just reaches across the room. We want no splattering off walls or ceiling.
Open the nozzle and select the flow to the ideal rate for the size room, 30 Gpm (113,5 Lpm) for 1,000 cubic feet (28,3 cubic meters), and so on.
Distribute the water evenly throughout the fire area by rotating the nozzle clockwise inside the room, or by some other means.
Shut off the flow immediately upon the disappearance of the flames. Condensed steam appears as steam expands out the windows or door, and upward out of the structure.
If you do these tasks you will perform an effective fog attack in a safe manner that will be successful 100% of the time.
The NFPA reports that in the United States about 75% of all structure fires are in one or two family detached dwellings. Also about the same percentage of structure fires are confined to the room of origin using a single attack line. In view of these facts, every fire department (brigade) should be able to handle your structure fires easily using the water that is carried on your fire trucks. There should be no excuse for suffering a fatality during any of these operations. The combination attack, backed up by the 3D pulse fog attack should guarantee that a structural fire attack can be conducted safely, 100% of the time.
