"I'm happy with what I have, so why confuse me with another hose size?" While there have been hundreds of thousands of discussions throughout the fire service on, for example, the flow merits of one nozzle or the penetration qualities of another, it must be understood that the most important...
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"I'm happy with what I have, so why confuse me with another hose size?"
While there have been hundreds of thousands of discussions throughout the fire service on, for example, the flow merits of one nozzle or the penetration qualities of another, it must be understood that the most important element of attack line operation is gallons per minute (gpm). Just when fire departments are realizing the need to flow more water on more intense fires, however, many are being forced to operate with fewer members. This shortage becomes critical during first-arriving-company operations, when relatively few on-scene firefighters have to simultaneously perform command, size-up, rescue and fire suppression operational tasks.
Photo by David P. Fornell
Looks can be deceiving. Two-inch hose generates only about half the friction loss of 1 3/4-inch hose but when they are laid side by side, it is hard to tell them apart. One way to identify the larger line is to compare the size of the coupling bowls, in this case, making the two-inch orange hose easy to spot.
Common sense tells us that fire service planners need to address the problem of increasing the gpm flow rate per line to better cope with larger fires but must also keep in mind that for that flow rate to be effective, the line has to be capable of being maneuvered inside a fire building by as few as two firefighters. For years, the only practical hoseline size that could flow over 200 gpm was 2 1/2 inches. But 2 1/2-inch line, while it can be easily stretched before it is charged, becomes almost impossible to operate offensively (moved rapidly) inside a building by a crew with limited staffing.
In a search for an answer, it's been described how 1 3/4-inch line could be designed to address the problem of the high-flow handline. This has led many departments to believe manufacturers' claims that the 1 3/4-inch line could flow up to 300 gpm on the fireground; however, the high engine pressures (above 300 psi) needed to generate this flow rate makes the line extremely stiff and hard to handle. Coupled with extremely high nozzle reaction forces, this makes flowing more than about 180 gpm through a 1 3/4-inch line impractical and, at times, downright dangerous on the fireground.
Facing the paradox: 2 1/2-inch line is too heavy and 1 3/4-inch line is too difficult to handle.
It's a matter of physics that to accomplish extinguishment, you must put enough water on the fire to overcome the heat being produced. That law deals with energy exchange during the physical reaction called combustion and cannot be changed. Simply put, if you don't flow enough water, the fire will not go out and the interior operating crew will remain in increasing danger until withdrawn.
If you want to flow more water with a limited staff, a good place to begin is to design a line that provides a relatively easy-to-handle conduit (hose size) coupled to a nozzle that flows a lot of water but doesn't generate unmanageable nozzle reaction force. Let's first discuss the merits of hoseline size.
While many departments are satisfied with their present handlines and attack strategy when there are enough personnel on the scene to enable the quick deployment of 2 1/2-inch initial or backup lines, a number of progressive fire officers are now investigating the addition of a "day line" one that provides for high flow rates yet can be easily and quickly deployed by the first-arriving firefighters when relatively few people are available, such as during daytime hours.
Because of its ability to provide easily attainable flow rates up to about 250 gpm, many of these officers are evaluating two-inch hoselines coupled to low-pressure or smooth-bore nozzles as an effective alternative to 1 3/4-inch and 2 1/2-inch hoselines when staffing is limited. Two-inch hose is a relatively common size in the marine industry and has been available for years. Standard practice on ships has been to equip the hose with two-inch threaded couplings; in some areas of New England, the use of two-inch hose equipped with one-third-turn Storz couplings is relatively common.