Proper Use Of Deck Guns

As your apparatus leaves quarters, you can see the massive cloud of boiling smoke swirl skyward. The dispatcher advises all units that multiple calls are being received reporting a working fire at a row of townhouses under construction. Arriving...


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As your apparatus leaves quarters, you can see the massive cloud of boiling smoke swirl skyward. The dispatcher advises all units that multiple calls are being received reporting a working fire at a row of townhouses under construction.

Arriving only minutes after the alarm, you are astounded at how far the fire has advanced. Already, four apartments are fully involved, fire not only out every window and door but covering every wall surface and roof. A slight breeze is blowing toward rows upon rows of other wood-frame apartments in various stages of construction, yet there are still eight more units of apartments attached to the burning ones, with fire undoubtedly spreading along through the cockloft beneath the roof. And here you are arriving first due!

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Photo by John Norman
The deck gun is very useful for knocking down large exterior fires where the line of sight is clear.

The advanced fire on arrival, particularly exterior fire, is the made-to-order situation for a pre-connected master stream device, the deck gun. Unfortunately, when I arrived at the scenario described above over 26 years ago, the "attack pumper" was outfitted with multiple 1 1/2-inch handlines but no deck gun, nor for that matter even a 2 1/2-inch pre-connect. The fire roared right past the puny streams from the pre-connects as ladder pipes and portable master streams were ultimately brought into play. Had a pre-connected stream of say 500 gpm been immediately available, however, it is likely that the fire would have been confined to an area less than half the total of 36 units destroyed.

The pre-connected master stream device, particularly when coupled with a bed of large-diameter supply hose or other method of sustaining a high-volume attack, is a tremendous fire attack weapon, although one that is not often used. It is not used often for two reasons: the low percentage of fires that reach very advanced stages and the lack of knowledge and experience in how to use it properly.

Since most of the fires in this country involve one- and two-family dwellings, the deck gun is rarely required; the private house just does not produce enough fire on its exterior to demand 500 gpm or more to knock down...usually. The exception involves wood-frame homes that are covered with combustible siding and spaced close together. In this case, fire venting from a lower-floor window of the fire building will quickly spread up the exterior of both buildings, extending into the upper floors of each with lightning speed through windows and attic eaves. A strong handline could knock this fire down but the deck gun is probably a better choice. It can quickly sweep along the eaves lines with its stream, the excess water cascading down the burning side, extinguishing the entire area in under 30 seconds. The big advantages of this device for this use is its speed (it can be employed off the booster tank as soon as the pumps are engaged) and its minimal manpower requirements (only one person is needed for this task; the engine chauffeur can often do it alone.) Remember, the fire is still burning inside the original fire building. The rest of the first-due engine crew should be stretching a pre-connected 1 3/4-inch handline to operate inside the house.

Fixed master streams are very useful for knocking down large exterior fires such as those in lumber yards, rows of stacked boats in winter storage at marinas and other open areas where there is a clear line of sight from the deck gun to large areas of flame. The deck gun may also be very useful at interior fires when properly positioned and used but it does have its limitations. Deck guns are not very useful at residential fires, even those that are fully involved with fire showing from every window, unless the building is threatening exposures. The reason is the design of the home and the placement of the apparatus. Due to home setbacks from the street (sidewalk and front yard), the deck gun is likely going to be at least 30 feet from the building. Houses are built with relatively small window areas, typically 30 inches wide by 40-48 inches high. Water extinguishes best by landing on and cooling the surface of burning Class A fuels. As a result, when a deck gun is applied to a house fire, it extinguishes only what is directly in line with the window opening, a 2 1/2-by-four-foot area out of a room that is approximately 10 feet by eight feet. The rest of the area on the sides of the windows continues to burn with little effect from the massive attack on the small area in line with the window. (That highlights one of the greatest advantages of another type of master stream, the tower ladder.)

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