Tuesday, February 23, 2016

2" hose, The middle child of the fire service



                                    2" hose, the middle child of the fire service

 Here is some perspective on the parallels of the 2" fire hose and being the middle child. The latter as you might guess is this author, so I claim the authority to speak to those truths. The former is in most cases misunderstood, and in my opinion is an underutilized attack choice for specific scenarios.

 Where does the middle child of fire attack belong? That is a subjective question answered by an equally subjective statement. The 2" line belongs in the hands of a crew fighting an advanced fire condition with a doubtful outcome, and/or a situation that has an inherent delay of reaching the fire due to the multiple turns or obstacles from the pump to the seat of the fire. Understand that a doubtful fire for you and your organization, may not be one for mine, or visa-versa. If you are not interested in thinking about the rate of water application vs nozzle reaction and the applicable maneuverability of the hose, then the 2" hose is not for you. I cannot speak to the history of the 2" hose but, I can explain what modern 2" can do for a short staffed crew that is dealing with a fire different than the bread and butter operation.  

 A fire in a residential high rise built pre 1995, with no PRV’s is one of these special types of incidents. The stand pipe design was built around the 2½ hose and a low pressure nozzle. Specifically to get 250 GPM to a low pressure high volume tip fastened to 150 feet of hose. The fire formula for these incidents are predicated on an advanced fire beyond it's room of origin. The fire service if very comfortable with the 1.75 because we make it work with repetition at ground level. The comfort with the 1¾ hand line has some merit but the stand pipe scenario does not allow for taking the easy way out. The same 1200sq ft. house fire configured as a ranch home is much worse 70 feet in the air with limited access. If you think not, then wait 10 minutes on the street the next time you arrive at a bread and butter house fire, and then see what gpm attack package you would rather use. 250 GPM is a must!


 In my own reality based back yard testing the modern 2" hose averages 15 - 20 pounds of friction loss per 50 ft. in the 250 gpm range with a 1-1/16th tip. The effective fire flow range of this attack hose is as much based on the hydraulics as it is the training and ability of the fire attack crew. The reaction force of a 1-1/8 smooth bore at 50 psi, or even 65 psi, is the same regardless of what hose is behind it. You need to practice handling these upper limit flows! Nozzle mechanics is a basic job requirement that is sorely glazed over by most. Respect the 2" line when flowing this amount of water. Do not treat it like a 1.75 as that nozzle reaction could surprise you.

  The next step is understanding the increased mobility of 2" vs 2 ½ . This is the "why" you should consider 2 inch hose!! The 2-½ is much heavier per length, and unless you have the bale 1/2 open, the 2.5 is much harder to bend around a turn. The shear amount of water pushing against the inner wall of the deuce and a half resists any effort to bend the hose. I cannot offer a scientific measurement of the force needed to bend the 2" but I can tell you that the effort is much, much less.


Matier, Shupe, Herbst 
The 2" does have its limitations. It does not come from the same low friction loss pedigree as the 2½. The 2" has an effective length where it must operate to justify its use. Friction loss is predicated on the rate of flow and overall distance of the hose. After using several different manufacturers, my observation is that 400 feet would be the upper limit if you still need to get the upper limit flows.  Some companies in FDNY were using it as a lead 100ft length on a residential stand pipe as a trial run. I would suggest that if you have the staffing to support a 2.5 then there is no need to switch to the 2". For the rest of the fire service where people are at a premium, you can find a good fit with this intermediate line. 


  So where could a 3 person engine use a 250 gpm line that has superior mobility and not exceed the length limitations? A pre 95 standpipe system. An attached garage fire. A large open floor plan modern house fire. There are specific scenarios that would be conquered more quickly by the understaffed company with using this hose line. With that said, a pre planned attack for these scenarios should be identified so as to not make the mistake of NOT pulling the 2.5 when warranted. Using the A.D.U.L.T. acronym is the best place to start. 

  From the street - to the pump - to the discharge point - to the nozzle – to the seat of the fire. A simple plan but the choices of equipment effect your efficiency. If you have the benefit of multiple companies responding to one of these incidents, then I suggest you stick with the high volume/low pressure 2 ½ hose. If your organization could benefit from using this alternative, clearly map out where this should be used with the explanation of why. 

                                              

                                             The 2" is not a replacement for the 2 ½!

 A target flow for the middle child of fire attack in my opinion is 220 to 250 gpm. I recognize this is not the higher level of fire attack via a 2½ at 265 gpm. However; I also recognize that modern 2" can do 265 quite easily. Look at your attack packages and evaluate the operational range. Get that hose wet with a pito tube, and find out what your crew can do with an under pumped nozzle as well as with the over pumped one. 50 psi at the smooth bore tip is the target but the variables are too many to list for an exact pressure. Shoot for 50 and run the nozzle wide open with a good grip.


 The middle child takes the wisdom of the older 2½, and blends it with the speed of the younger, more deploy-able 1¾. The results are a hard hitting attack package that gives smaller crews a better chance at taking the building back from the fire. If you are not fortunate enough to work for a big organization that can put a couple dozen hands on a working fire, then consider a look at putting all of the fire service siblings in play.


Photos are by the author.