Back in July, I discussed the importance of selecting an initial attack hose line that actually has the capability of knocking down the fire at hand. In all too many cases, we see departments stretch an "all purpose" 1-3/4" line on fires, the volume of which is well beyond the line's flow capabilities, most likely because it is easy to stretch and operate.
"Fyredup" commented that his department uses 2" attack lines for flows up to 300-GPM, and for those faced with wanting to apply more water with limited personnel, this might prove a good solution.
Two-inch hose has been widely used for years in the marine and snow making industries. With the advent of the three-part coupling that provides 1-1/2" threads its use in the fire service is growing, but as with any "too good to be true" product, you need to understand its advantages and disadvantages before deciding that it's right for your operation.
Slightly wider than 1-3/4," is has about half its friction loss so it will flow twice the water at the same pressure. In the photo, it's hard to tell them apart—2" is the orange line.
- It is not much larger than 1-3/4" hose. Often, the same amount of 2" hose will fit in the same hose bed as the smaller line
- It will deliver the same flow as 1-3/4" line at about one half the engine pressure
- It has the same 1-1/2" hose threads as the smaller attack lines and is as easy to deploy
- It can easily flow 250-GPM, the same as a 2-1/2" line, but full, weighs 43-lbs. per 50' length vs. 105-lbs. for 2-1/2"
- While dry, it weighs almost the same as 1-3/4" hose, when filled with water its weight is heavier—43-lbs. per 50' length vs. 38-lbs. for 1-3/4"
- While the charged 2" line looks and handles like 1-3/4" hose, its high-flow characteristics will allow generation of high nozzle reaction forces—the same as those experienced when operating 2-1/2" hose lines at the same flow rates.
Before deciding to add 2" hose to a firefighting toolbox, departments must consider the enigma of while 2" is able to deliver high flow rates to the nozzle, there is the problem of the operator safely and effectively utilizing these flows during attack operations. When investigating the advantages of 2" line, it must be kept in mind that proper nozzle selection becomes extremely important if it is desired to exploit the line's full knockdown potential.
I've seen time and time again, departments using 1-3/4" hose with nozzles designed for 1-1/2" line which kind of defeats the purpose of purchasing hose designed to flow more water. In the case of 2", unless you feel more macho hauling around a heavier hose line for no good reason, you need to carefully evaluate nozzle hardware that is matched to the larger line's flow capabilities.
While nozzles that operate at 100-PSI nozzle pressure can function perfectly well from a flow standpoint, they can cause handling problems when operated by one or two firefighters. To lower the nozzle reaction force, you should to consider equipping 2" hose with either low pressure (50-PSI) combination or smooth bore nozzles.
Can 2" help create an all purpose hand line that will allow us to get rid of the other hose sizes? Not really. It makes little sense to replace 1-3/4" line (or 1-1/2" for that matter) if you are operating in the 100 to 150-GPM range. Practical experience is proving that 2" hose is an excellent replacement for 2-1/2" attack lines, flowing 250-GPM from either a 50-PSI combination nozzle or 1-1/8" smooth bore. Keep in mind however, that while this line is more maneuverable and easier to advance than a charged 2-1/2", it generates the same nozzle reaction while flowing the same water as the big line.
As an example, in our department, we preconnect two, 200' 1-3/4" lines with 150-GPM @ 50-PSI nozzles and one 200' 2" line with a 250-GPM @ 50-PSI combination nozzle. It happens that all are charged at the same 150-PSI pump pressure to deliver their desired flows. Because there is practically no difference in the effort needed to deploy either size line, there is no reluctance by a two person crew to pull the 2" if a higher flow rate is dictated. In times past, a heavy 2-1/2" line with a brass playpipe may not have been the officer's first choice, even if its flow capabilities were needed, simply because it was so hard for a small crew to handle.
Because of its reduced friction loss numbers over 1-3/4" line, 2" hose offers an advantage for standpipe operations where lower than anticipated standpipe pressures on the fire floor can (and have been) encountered, and its size and weight when charged makes it easier to stretch out of a stairwell and into the involved space.
So, if you replace your 2-1/2" attack lines with 2", what do you do with the big hose? That's easy. Use it to supply a 500-GPM attack monitor, but that's another story.