With the advent of the Interstate Highway System in the 1950s came the inevitable consequence of suburban sprawl. As populations shifted from older inner cities to the suburbs, developers realized the need for mega-malls, office buildings, hotels, high-rack storage warehouses and high-rise apartment...
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The first order of business is assembling a "standpipe pack." According to Danbury, CT, Fire Captain David Fornell, "Departments experienced in high-rise operations say that nothing less than 2 1/2-inch hose should be used. Companies carrying 1 1/2-inch single jacket rack hose coupled to plastic low flow nozzles for high-rise operations should expect high fire losses as well as increased injury rates for both firefighters and occupants" (Fire Stream Management Handbook).
Some readers may throw up their hands at this point and say, "We don't have the manpower to advance a 2 1/2-inch line." But the fire doesn't care. If the fire requires 200 gpm to darken down, then that's what it takes. Furthermore, if only 65 psi residual is available at an outlet, it's obvious that a 1 1/2-inch line with a 100-gpm nozzle rated at 100 psi is doomed to failure. As Fornell notes, "For high-rise use, thermoplastic-lined hose is an excellent replacement for standard-construction, double-jacketed hose. In this example, 100 feet of thermoplastic-lined 2 1/2-inch hose weighs six pounds less and provides a smaller pack than 100 feet of rubber-lined 1 3/4-inch hose. The 1 3/4-inch hose and low-pressure nozzle could be expected to provide an average flow from 125 to 160 gpm. At the same standpipe pressures, the 2 1/2-inch lightweight hose with 1 1/8-inch smooth-bore nozzle will flow over 250 gpm."
"But what about nozzle reaction?" the naysayers will cry. "I've only got myself and one other guy available to advance the line!" To counter this argument, Fornell offers the following tip sizes and their resultant flows, nozzle reaction and friction losses:
|1/2"||50 psi||20lb.||53 gpm||2 1/2"||1/2 psi|
|3/4"||50 psi||44lb.||118 gpm||2 1/2"||2 1/2 psi|
|1 1/8"||50 psi||99lb.||266 gpm||2 1/2"||15 psi|
|Fog||100 psi||76lb.||100 gpm||1 1/2"||25 psi|
|Fog*||75 psi||44lb.||100 gpm||1 1/2"||25 psi|
If it is assumed that a firefighter can safely handle one-half his or her body weight in nozzle reaction force, two firefighters should be able to briefly manage a 1 1/8-inch tip at 50 psi, flowing 266 gpm (in theory, at least but get help fast).
If low residual pressures are found on the system, the use of a smaller three-quarter-inch or half-inch "stacked tip" may allow the company to develop an adequate fire stream with minimal friction losses in the 2 1/2 -inch hose.
As a final argument against the use of 2 1/2-inch standpipe hose, some will suggest, "We'll just pump into the fire department connection, that will give us all the pressure we need." This argument fails to address the following concerns:
- The fire department connection may be out of service due to damaged threads, obstruction with foreign objects, etc.
- In extremely tall buildings, head pressure may be excessive.
- Pressure-regulating devices may be present at hose outlets. These should be removed and pressure maintained by manually controlling the outlet valve, if possible.
- Supply lines to the fire department connection are frequently cut by falling glass.
In short, the wise fire department will plan for the worst-case scenario a huge fire on an upper floor, the fire pumps are out and the fire department connection has a tin can jammed in it. Bring the 2 1/2 -inch thermoplastic hose with an 1 1/8-by-half-inch anodized aluminum "stacked tip." There's a lot at stake here; leave the 1 1/2-inch hose on the truck.
Photo by Lance Peeples
A Class III standpipe located in an enclosed stairwell. If occupants advance a hoseline into the hallway and then retreat, the stairwell door is blocked open. This could severely threaten occupants above the fire. The use of Class III systems is declining because of concerns about the wisdom of having occupants attack fires.
How much 2 1/2-inch hose should we bring? The "actual length" method for determining hose connections as described in the Fire Protection Handbook requires hose connections "such that enough connections are provided to reach all portions of the area served with a 100-foot hose that has a nozzle with a 30-foot reach." However, if the Class III outlet is in the public hall, that would necessitate making the connection on the floor below the fire. In fact, it is always good practice to make the connection on the floor below the fire. This allows the control valve to be adjusted without being subjected to heat and smoke. Caution would suggest that we make allowance for unforeseen complications i.e.: poor stream reach, scissor stairs, wrong stairway, etc. Consequently, it would appear that four lengths should be carried in initially. According to Norman, other items which may prove useful are spanner wrenches, hose thread adapters, a 10-inch pipe wrench (in case valve hand-wheel is missing), door chocks and door latch markers.